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Diffstat (limited to 'lib/libsqlite3/src/select.c')
| -rw-r--r-- | lib/libsqlite3/src/select.c | 5616 |
1 files changed, 0 insertions, 5616 deletions
diff --git a/lib/libsqlite3/src/select.c b/lib/libsqlite3/src/select.c deleted file mode 100644 index fad46f0b470..00000000000 --- a/lib/libsqlite3/src/select.c +++ /dev/null @@ -1,5616 +0,0 @@ -/* -** 2001 September 15 -** -** The author disclaims copyright to this source code. In place of -** a legal notice, here is a blessing: -** -** May you do good and not evil. -** May you find forgiveness for yourself and forgive others. -** May you share freely, never taking more than you give. -** -************************************************************************* -** This file contains C code routines that are called by the parser -** to handle SELECT statements in SQLite. -*/ -#include "sqliteInt.h" - -/* -** Trace output macros -*/ -#if SELECTTRACE_ENABLED -/***/ int sqlite3SelectTrace = 0; -# define SELECTTRACE(K,P,S,X) \ - if(sqlite3SelectTrace&(K)) \ - sqlite3DebugPrintf("%*s%s.%p: ",(P)->nSelectIndent*2-2,"",\ - (S)->zSelName,(S)),\ - sqlite3DebugPrintf X -#else -# define SELECTTRACE(K,P,S,X) -#endif - - -/* -** An instance of the following object is used to record information about -** how to process the DISTINCT keyword, to simplify passing that information -** into the selectInnerLoop() routine. -*/ -typedef struct DistinctCtx DistinctCtx; -struct DistinctCtx { - u8 isTnct; /* True if the DISTINCT keyword is present */ - u8 eTnctType; /* One of the WHERE_DISTINCT_* operators */ - int tabTnct; /* Ephemeral table used for DISTINCT processing */ - int addrTnct; /* Address of OP_OpenEphemeral opcode for tabTnct */ -}; - -/* -** An instance of the following object is used to record information about -** the ORDER BY (or GROUP BY) clause of query is being coded. -*/ -typedef struct SortCtx SortCtx; -struct SortCtx { - ExprList *pOrderBy; /* The ORDER BY (or GROUP BY clause) */ - int nOBSat; /* Number of ORDER BY terms satisfied by indices */ - int iECursor; /* Cursor number for the sorter */ - int regReturn; /* Register holding block-output return address */ - int labelBkOut; /* Start label for the block-output subroutine */ - int addrSortIndex; /* Address of the OP_SorterOpen or OP_OpenEphemeral */ - u8 sortFlags; /* Zero or more SORTFLAG_* bits */ -}; -#define SORTFLAG_UseSorter 0x01 /* Use SorterOpen instead of OpenEphemeral */ - -/* -** Delete all the content of a Select structure. Deallocate the structure -** itself only if bFree is true. -*/ -static void clearSelect(sqlite3 *db, Select *p, int bFree){ - while( p ){ - Select *pPrior = p->pPrior; - sqlite3ExprListDelete(db, p->pEList); - sqlite3SrcListDelete(db, p->pSrc); - sqlite3ExprDelete(db, p->pWhere); - sqlite3ExprListDelete(db, p->pGroupBy); - sqlite3ExprDelete(db, p->pHaving); - sqlite3ExprListDelete(db, p->pOrderBy); - sqlite3ExprDelete(db, p->pLimit); - sqlite3ExprDelete(db, p->pOffset); - sqlite3WithDelete(db, p->pWith); - if( bFree ) sqlite3DbFree(db, p); - p = pPrior; - bFree = 1; - } -} - -/* -** Initialize a SelectDest structure. -*/ -void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){ - pDest->eDest = (u8)eDest; - pDest->iSDParm = iParm; - pDest->affSdst = 0; - pDest->iSdst = 0; - pDest->nSdst = 0; -} - - -/* -** Allocate a new Select structure and return a pointer to that -** structure. -*/ -Select *sqlite3SelectNew( - Parse *pParse, /* Parsing context */ - ExprList *pEList, /* which columns to include in the result */ - SrcList *pSrc, /* the FROM clause -- which tables to scan */ - Expr *pWhere, /* the WHERE clause */ - ExprList *pGroupBy, /* the GROUP BY clause */ - Expr *pHaving, /* the HAVING clause */ - ExprList *pOrderBy, /* the ORDER BY clause */ - u16 selFlags, /* Flag parameters, such as SF_Distinct */ - Expr *pLimit, /* LIMIT value. NULL means not used */ - Expr *pOffset /* OFFSET value. NULL means no offset */ -){ - Select *pNew; - Select standin; - sqlite3 *db = pParse->db; - pNew = sqlite3DbMallocZero(db, sizeof(*pNew) ); - if( pNew==0 ){ - assert( db->mallocFailed ); - pNew = &standin; - memset(pNew, 0, sizeof(*pNew)); - } - if( pEList==0 ){ - pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0)); - } - pNew->pEList = pEList; - if( pSrc==0 ) pSrc = sqlite3DbMallocZero(db, sizeof(*pSrc)); - pNew->pSrc = pSrc; - pNew->pWhere = pWhere; - pNew->pGroupBy = pGroupBy; - pNew->pHaving = pHaving; - pNew->pOrderBy = pOrderBy; - pNew->selFlags = selFlags; - pNew->op = TK_SELECT; - pNew->pLimit = pLimit; - pNew->pOffset = pOffset; - assert( pOffset==0 || pLimit!=0 || pParse->nErr>0 || db->mallocFailed!=0 ); - pNew->addrOpenEphm[0] = -1; - pNew->addrOpenEphm[1] = -1; - if( db->mallocFailed ) { - clearSelect(db, pNew, pNew!=&standin); - pNew = 0; - }else{ - assert( pNew->pSrc!=0 || pParse->nErr>0 ); - } - assert( pNew!=&standin ); - return pNew; -} - -#if SELECTTRACE_ENABLED -/* -** Set the name of a Select object -*/ -void sqlite3SelectSetName(Select *p, const char *zName){ - if( p && zName ){ - sqlite3_snprintf(sizeof(p->zSelName), p->zSelName, "%s", zName); - } -} -#endif - - -/* -** Delete the given Select structure and all of its substructures. -*/ -void sqlite3SelectDelete(sqlite3 *db, Select *p){ - clearSelect(db, p, 1); -} - -/* -** Return a pointer to the right-most SELECT statement in a compound. -*/ -static Select *findRightmost(Select *p){ - while( p->pNext ) p = p->pNext; - return p; -} - -/* -** Given 1 to 3 identifiers preceding the JOIN keyword, determine the -** type of join. Return an integer constant that expresses that type -** in terms of the following bit values: -** -** JT_INNER -** JT_CROSS -** JT_OUTER -** JT_NATURAL -** JT_LEFT -** JT_RIGHT -** -** A full outer join is the combination of JT_LEFT and JT_RIGHT. -** -** If an illegal or unsupported join type is seen, then still return -** a join type, but put an error in the pParse structure. -*/ -int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){ - int jointype = 0; - Token *apAll[3]; - Token *p; - /* 0123456789 123456789 123456789 123 */ - static const char zKeyText[] = "naturaleftouterightfullinnercross"; - static const struct { - u8 i; /* Beginning of keyword text in zKeyText[] */ - u8 nChar; /* Length of the keyword in characters */ - u8 code; /* Join type mask */ - } aKeyword[] = { - /* natural */ { 0, 7, JT_NATURAL }, - /* left */ { 6, 4, JT_LEFT|JT_OUTER }, - /* outer */ { 10, 5, JT_OUTER }, - /* right */ { 14, 5, JT_RIGHT|JT_OUTER }, - /* full */ { 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER }, - /* inner */ { 23, 5, JT_INNER }, - /* cross */ { 28, 5, JT_INNER|JT_CROSS }, - }; - int i, j; - apAll[0] = pA; - apAll[1] = pB; - apAll[2] = pC; - for(i=0; i<3 && apAll[i]; i++){ - p = apAll[i]; - for(j=0; j<ArraySize(aKeyword); j++){ - if( p->n==aKeyword[j].nChar - && sqlite3StrNICmp((char*)p->z, &zKeyText[aKeyword[j].i], p->n)==0 ){ - jointype |= aKeyword[j].code; - break; - } - } - testcase( j==0 || j==1 || j==2 || j==3 || j==4 || j==5 || j==6 ); - if( j>=ArraySize(aKeyword) ){ - jointype |= JT_ERROR; - break; - } - } - if( - (jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) || - (jointype & JT_ERROR)!=0 - ){ - const char *zSp = " "; - assert( pB!=0 ); - if( pC==0 ){ zSp++; } - sqlite3ErrorMsg(pParse, "unknown or unsupported join type: " - "%T %T%s%T", pA, pB, zSp, pC); - jointype = JT_INNER; - }else if( (jointype & JT_OUTER)!=0 - && (jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ){ - sqlite3ErrorMsg(pParse, - "RIGHT and FULL OUTER JOINs are not currently supported"); - jointype = JT_INNER; - } - return jointype; -} - -/* -** Return the index of a column in a table. Return -1 if the column -** is not contained in the table. -*/ -static int columnIndex(Table *pTab, const char *zCol){ - int i; - for(i=0; i<pTab->nCol; i++){ - if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i; - } - return -1; -} - -/* -** Search the first N tables in pSrc, from left to right, looking for a -** table that has a column named zCol. -** -** When found, set *piTab and *piCol to the table index and column index -** of the matching column and return TRUE. -** -** If not found, return FALSE. -*/ -static int tableAndColumnIndex( - SrcList *pSrc, /* Array of tables to search */ - int N, /* Number of tables in pSrc->a[] to search */ - const char *zCol, /* Name of the column we are looking for */ - int *piTab, /* Write index of pSrc->a[] here */ - int *piCol /* Write index of pSrc->a[*piTab].pTab->aCol[] here */ -){ - int i; /* For looping over tables in pSrc */ - int iCol; /* Index of column matching zCol */ - - assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */ - for(i=0; i<N; i++){ - iCol = columnIndex(pSrc->a[i].pTab, zCol); - if( iCol>=0 ){ - if( piTab ){ - *piTab = i; - *piCol = iCol; - } - return 1; - } - } - return 0; -} - -/* -** This function is used to add terms implied by JOIN syntax to the -** WHERE clause expression of a SELECT statement. The new term, which -** is ANDed with the existing WHERE clause, is of the form: -** -** (tab1.col1 = tab2.col2) -** -** where tab1 is the iSrc'th table in SrcList pSrc and tab2 is the -** (iSrc+1)'th. Column col1 is column iColLeft of tab1, and col2 is -** column iColRight of tab2. -*/ -static void addWhereTerm( - Parse *pParse, /* Parsing context */ - SrcList *pSrc, /* List of tables in FROM clause */ - int iLeft, /* Index of first table to join in pSrc */ - int iColLeft, /* Index of column in first table */ - int iRight, /* Index of second table in pSrc */ - int iColRight, /* Index of column in second table */ - int isOuterJoin, /* True if this is an OUTER join */ - Expr **ppWhere /* IN/OUT: The WHERE clause to add to */ -){ - sqlite3 *db = pParse->db; - Expr *pE1; - Expr *pE2; - Expr *pEq; - - assert( iLeft<iRight ); - assert( pSrc->nSrc>iRight ); - assert( pSrc->a[iLeft].pTab ); - assert( pSrc->a[iRight].pTab ); - - pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iColLeft); - pE2 = sqlite3CreateColumnExpr(db, pSrc, iRight, iColRight); - - pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2, 0); - if( pEq && isOuterJoin ){ - ExprSetProperty(pEq, EP_FromJoin); - assert( !ExprHasProperty(pEq, EP_TokenOnly|EP_Reduced) ); - ExprSetVVAProperty(pEq, EP_NoReduce); - pEq->iRightJoinTable = (i16)pE2->iTable; - } - *ppWhere = sqlite3ExprAnd(db, *ppWhere, pEq); -} - -/* -** Set the EP_FromJoin property on all terms of the given expression. -** And set the Expr.iRightJoinTable to iTable for every term in the -** expression. -** -** The EP_FromJoin property is used on terms of an expression to tell -** the LEFT OUTER JOIN processing logic that this term is part of the -** join restriction specified in the ON or USING clause and not a part -** of the more general WHERE clause. These terms are moved over to the -** WHERE clause during join processing but we need to remember that they -** originated in the ON or USING clause. -** -** The Expr.iRightJoinTable tells the WHERE clause processing that the -** expression depends on table iRightJoinTable even if that table is not -** explicitly mentioned in the expression. That information is needed -** for cases like this: -** -** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5 -** -** The where clause needs to defer the handling of the t1.x=5 -** term until after the t2 loop of the join. In that way, a -** NULL t2 row will be inserted whenever t1.x!=5. If we do not -** defer the handling of t1.x=5, it will be processed immediately -** after the t1 loop and rows with t1.x!=5 will never appear in -** the output, which is incorrect. -*/ -static void setJoinExpr(Expr *p, int iTable){ - while( p ){ - ExprSetProperty(p, EP_FromJoin); - assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) ); - ExprSetVVAProperty(p, EP_NoReduce); - p->iRightJoinTable = (i16)iTable; - if( p->op==TK_FUNCTION && p->x.pList ){ - int i; - for(i=0; i<p->x.pList->nExpr; i++){ - setJoinExpr(p->x.pList->a[i].pExpr, iTable); - } - } - setJoinExpr(p->pLeft, iTable); - p = p->pRight; - } -} - -/* -** This routine processes the join information for a SELECT statement. -** ON and USING clauses are converted into extra terms of the WHERE clause. -** NATURAL joins also create extra WHERE clause terms. -** -** The terms of a FROM clause are contained in the Select.pSrc structure. -** The left most table is the first entry in Select.pSrc. The right-most -** table is the last entry. The join operator is held in the entry to -** the left. Thus entry 0 contains the join operator for the join between -** entries 0 and 1. Any ON or USING clauses associated with the join are -** also attached to the left entry. -** -** This routine returns the number of errors encountered. -*/ -static int sqliteProcessJoin(Parse *pParse, Select *p){ - SrcList *pSrc; /* All tables in the FROM clause */ - int i, j; /* Loop counters */ - struct SrcList_item *pLeft; /* Left table being joined */ - struct SrcList_item *pRight; /* Right table being joined */ - - pSrc = p->pSrc; - pLeft = &pSrc->a[0]; - pRight = &pLeft[1]; - for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){ - Table *pLeftTab = pLeft->pTab; - Table *pRightTab = pRight->pTab; - int isOuter; - - if( NEVER(pLeftTab==0 || pRightTab==0) ) continue; - isOuter = (pRight->fg.jointype & JT_OUTER)!=0; - - /* When the NATURAL keyword is present, add WHERE clause terms for - ** every column that the two tables have in common. - */ - if( pRight->fg.jointype & JT_NATURAL ){ - if( pRight->pOn || pRight->pUsing ){ - sqlite3ErrorMsg(pParse, "a NATURAL join may not have " - "an ON or USING clause", 0); - return 1; - } - for(j=0; j<pRightTab->nCol; j++){ - char *zName; /* Name of column in the right table */ - int iLeft; /* Matching left table */ - int iLeftCol; /* Matching column in the left table */ - - zName = pRightTab->aCol[j].zName; - if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) ){ - addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j, - isOuter, &p->pWhere); - } - } - } - - /* Disallow both ON and USING clauses in the same join - */ - if( pRight->pOn && pRight->pUsing ){ - sqlite3ErrorMsg(pParse, "cannot have both ON and USING " - "clauses in the same join"); - return 1; - } - - /* Add the ON clause to the end of the WHERE clause, connected by - ** an AND operator. - */ - if( pRight->pOn ){ - if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor); - p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn); - pRight->pOn = 0; - } - - /* Create extra terms on the WHERE clause for each column named - ** in the USING clause. Example: If the two tables to be joined are - ** A and B and the USING clause names X, Y, and Z, then add this - ** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z - ** Report an error if any column mentioned in the USING clause is - ** not contained in both tables to be joined. - */ - if( pRight->pUsing ){ - IdList *pList = pRight->pUsing; - for(j=0; j<pList->nId; j++){ - char *zName; /* Name of the term in the USING clause */ - int iLeft; /* Table on the left with matching column name */ - int iLeftCol; /* Column number of matching column on the left */ - int iRightCol; /* Column number of matching column on the right */ - - zName = pList->a[j].zName; - iRightCol = columnIndex(pRightTab, zName); - if( iRightCol<0 - || !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) - ){ - sqlite3ErrorMsg(pParse, "cannot join using column %s - column " - "not present in both tables", zName); - return 1; - } - addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, iRightCol, - isOuter, &p->pWhere); - } - } - } - return 0; -} - -/* Forward reference */ -static KeyInfo *keyInfoFromExprList( - Parse *pParse, /* Parsing context */ - ExprList *pList, /* Form the KeyInfo object from this ExprList */ - int iStart, /* Begin with this column of pList */ - int nExtra /* Add this many extra columns to the end */ -); - -/* -** Generate code that will push the record in registers regData -** through regData+nData-1 onto the sorter. -*/ -static void pushOntoSorter( - Parse *pParse, /* Parser context */ - SortCtx *pSort, /* Information about the ORDER BY clause */ - Select *pSelect, /* The whole SELECT statement */ - int regData, /* First register holding data to be sorted */ - int regOrigData, /* First register holding data before packing */ - int nData, /* Number of elements in the data array */ - int nPrefixReg /* No. of reg prior to regData available for use */ -){ - Vdbe *v = pParse->pVdbe; /* Stmt under construction */ - int bSeq = ((pSort->sortFlags & SORTFLAG_UseSorter)==0); - int nExpr = pSort->pOrderBy->nExpr; /* No. of ORDER BY terms */ - int nBase = nExpr + bSeq + nData; /* Fields in sorter record */ - int regBase; /* Regs for sorter record */ - int regRecord = ++pParse->nMem; /* Assembled sorter record */ - int nOBSat = pSort->nOBSat; /* ORDER BY terms to skip */ - int op; /* Opcode to add sorter record to sorter */ - - assert( bSeq==0 || bSeq==1 ); - assert( nData==1 || regData==regOrigData ); - if( nPrefixReg ){ - assert( nPrefixReg==nExpr+bSeq ); - regBase = regData - nExpr - bSeq; - }else{ - regBase = pParse->nMem + 1; - pParse->nMem += nBase; - } - sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData, - SQLITE_ECEL_DUP|SQLITE_ECEL_REF); - if( bSeq ){ - sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr); - } - if( nPrefixReg==0 ){ - sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+bSeq, nData); - } - - sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regRecord); - if( nOBSat>0 ){ - int regPrevKey; /* The first nOBSat columns of the previous row */ - int addrFirst; /* Address of the OP_IfNot opcode */ - int addrJmp; /* Address of the OP_Jump opcode */ - VdbeOp *pOp; /* Opcode that opens the sorter */ - int nKey; /* Number of sorting key columns, including OP_Sequence */ - KeyInfo *pKI; /* Original KeyInfo on the sorter table */ - - regPrevKey = pParse->nMem+1; - pParse->nMem += pSort->nOBSat; - nKey = nExpr - pSort->nOBSat + bSeq; - if( bSeq ){ - addrFirst = sqlite3VdbeAddOp1(v, OP_IfNot, regBase+nExpr); - }else{ - addrFirst = sqlite3VdbeAddOp1(v, OP_SequenceTest, pSort->iECursor); - } - VdbeCoverage(v); - sqlite3VdbeAddOp3(v, OP_Compare, regPrevKey, regBase, pSort->nOBSat); - pOp = sqlite3VdbeGetOp(v, pSort->addrSortIndex); - if( pParse->db->mallocFailed ) return; - pOp->p2 = nKey + nData; - pKI = pOp->p4.pKeyInfo; - memset(pKI->aSortOrder, 0, pKI->nField); /* Makes OP_Jump below testable */ - sqlite3VdbeChangeP4(v, -1, (char*)pKI, P4_KEYINFO); - testcase( pKI->nXField>2 ); - pOp->p4.pKeyInfo = keyInfoFromExprList(pParse, pSort->pOrderBy, nOBSat, - pKI->nXField-1); - addrJmp = sqlite3VdbeCurrentAddr(v); - sqlite3VdbeAddOp3(v, OP_Jump, addrJmp+1, 0, addrJmp+1); VdbeCoverage(v); - pSort->labelBkOut = sqlite3VdbeMakeLabel(v); - pSort->regReturn = ++pParse->nMem; - sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut); - sqlite3VdbeAddOp1(v, OP_ResetSorter, pSort->iECursor); - sqlite3VdbeJumpHere(v, addrFirst); - sqlite3ExprCodeMove(pParse, regBase, regPrevKey, pSort->nOBSat); - sqlite3VdbeJumpHere(v, addrJmp); - } - if( pSort->sortFlags & SORTFLAG_UseSorter ){ - op = OP_SorterInsert; - }else{ - op = OP_IdxInsert; - } - sqlite3VdbeAddOp2(v, op, pSort->iECursor, regRecord); - if( pSelect->iLimit ){ - int addr; - int iLimit; - if( pSelect->iOffset ){ - iLimit = pSelect->iOffset+1; - }else{ - iLimit = pSelect->iLimit; - } - addr = sqlite3VdbeAddOp3(v, OP_IfNotZero, iLimit, 0, 1); VdbeCoverage(v); - sqlite3VdbeAddOp1(v, OP_Last, pSort->iECursor); - sqlite3VdbeAddOp1(v, OP_Delete, pSort->iECursor); - sqlite3VdbeJumpHere(v, addr); - } -} - -/* -** Add code to implement the OFFSET -*/ -static void codeOffset( - Vdbe *v, /* Generate code into this VM */ - int iOffset, /* Register holding the offset counter */ - int iContinue /* Jump here to skip the current record */ -){ - if( iOffset>0 ){ - sqlite3VdbeAddOp3(v, OP_IfPos, iOffset, iContinue, 1); VdbeCoverage(v); - VdbeComment((v, "OFFSET")); - } -} - -/* -** Add code that will check to make sure the N registers starting at iMem -** form a distinct entry. iTab is a sorting index that holds previously -** seen combinations of the N values. A new entry is made in iTab -** if the current N values are new. -** -** A jump to addrRepeat is made and the N+1 values are popped from the -** stack if the top N elements are not distinct. -*/ -static void codeDistinct( - Parse *pParse, /* Parsing and code generating context */ - int iTab, /* A sorting index used to test for distinctness */ - int addrRepeat, /* Jump to here if not distinct */ - int N, /* Number of elements */ - int iMem /* First element */ -){ - Vdbe *v; - int r1; - - v = pParse->pVdbe; - r1 = sqlite3GetTempReg(pParse); - sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, iMem, N); VdbeCoverage(v); - sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1); - sqlite3VdbeAddOp2(v, OP_IdxInsert, iTab, r1); - sqlite3ReleaseTempReg(pParse, r1); -} - -#ifndef SQLITE_OMIT_SUBQUERY -/* -** Generate an error message when a SELECT is used within a subexpression -** (example: "a IN (SELECT * FROM table)") but it has more than 1 result -** column. We do this in a subroutine because the error used to occur -** in multiple places. (The error only occurs in one place now, but we -** retain the subroutine to minimize code disruption.) -*/ -static int checkForMultiColumnSelectError( - Parse *pParse, /* Parse context. */ - SelectDest *pDest, /* Destination of SELECT results */ - int nExpr /* Number of result columns returned by SELECT */ -){ - int eDest = pDest->eDest; - if( nExpr>1 && (eDest==SRT_Mem || eDest==SRT_Set) ){ - sqlite3ErrorMsg(pParse, "only a single result allowed for " - "a SELECT that is part of an expression"); - return 1; - }else{ - return 0; - } -} -#endif - -/* -** This routine generates the code for the inside of the inner loop -** of a SELECT. -** -** If srcTab is negative, then the pEList expressions -** are evaluated in order to get the data for this row. If srcTab is -** zero or more, then data is pulled from srcTab and pEList is used only -** to get number columns and the datatype for each column. -*/ -static void selectInnerLoop( - Parse *pParse, /* The parser context */ - Select *p, /* The complete select statement being coded */ - ExprList *pEList, /* List of values being extracted */ - int srcTab, /* Pull data from this table */ - SortCtx *pSort, /* If not NULL, info on how to process ORDER BY */ - DistinctCtx *pDistinct, /* If not NULL, info on how to process DISTINCT */ - SelectDest *pDest, /* How to dispose of the results */ - int iContinue, /* Jump here to continue with next row */ - int iBreak /* Jump here to break out of the inner loop */ -){ - Vdbe *v = pParse->pVdbe; - int i; - int hasDistinct; /* True if the DISTINCT keyword is present */ - int regResult; /* Start of memory holding result set */ - int eDest = pDest->eDest; /* How to dispose of results */ - int iParm = pDest->iSDParm; /* First argument to disposal method */ - int nResultCol; /* Number of result columns */ - int nPrefixReg = 0; /* Number of extra registers before regResult */ - - assert( v ); - assert( pEList!=0 ); - hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP; - if( pSort && pSort->pOrderBy==0 ) pSort = 0; - if( pSort==0 && !hasDistinct ){ - assert( iContinue!=0 ); - codeOffset(v, p->iOffset, iContinue); - } - - /* Pull the requested columns. - */ - nResultCol = pEList->nExpr; - - if( pDest->iSdst==0 ){ - if( pSort ){ - nPrefixReg = pSort->pOrderBy->nExpr; - if( !(pSort->sortFlags & SORTFLAG_UseSorter) ) nPrefixReg++; - pParse->nMem += nPrefixReg; - } - pDest->iSdst = pParse->nMem+1; - pParse->nMem += nResultCol; - }else if( pDest->iSdst+nResultCol > pParse->nMem ){ - /* This is an error condition that can result, for example, when a SELECT - ** on the right-hand side of an INSERT contains more result columns than - ** there are columns in the table on the left. The error will be caught - ** and reported later. But we need to make sure enough memory is allocated - ** to avoid other spurious errors in the meantime. */ - pParse->nMem += nResultCol; - } - pDest->nSdst = nResultCol; - regResult = pDest->iSdst; - if( srcTab>=0 ){ - for(i=0; i<nResultCol; i++){ - sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i); - VdbeComment((v, "%s", pEList->a[i].zName)); - } - }else if( eDest!=SRT_Exists ){ - /* If the destination is an EXISTS(...) expression, the actual - ** values returned by the SELECT are not required. - */ - u8 ecelFlags; - if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){ - ecelFlags = SQLITE_ECEL_DUP; - }else{ - ecelFlags = 0; - } - sqlite3ExprCodeExprList(pParse, pEList, regResult, 0, ecelFlags); - } - - /* If the DISTINCT keyword was present on the SELECT statement - ** and this row has been seen before, then do not make this row - ** part of the result. - */ - if( hasDistinct ){ - switch( pDistinct->eTnctType ){ - case WHERE_DISTINCT_ORDERED: { - VdbeOp *pOp; /* No longer required OpenEphemeral instr. */ - int iJump; /* Jump destination */ - int regPrev; /* Previous row content */ - - /* Allocate space for the previous row */ - regPrev = pParse->nMem+1; - pParse->nMem += nResultCol; - - /* Change the OP_OpenEphemeral coded earlier to an OP_Null - ** sets the MEM_Cleared bit on the first register of the - ** previous value. This will cause the OP_Ne below to always - ** fail on the first iteration of the loop even if the first - ** row is all NULLs. - */ - sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct); - pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct); - pOp->opcode = OP_Null; - pOp->p1 = 1; - pOp->p2 = regPrev; - - iJump = sqlite3VdbeCurrentAddr(v) + nResultCol; - for(i=0; i<nResultCol; i++){ - CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[i].pExpr); - if( i<nResultCol-1 ){ - sqlite3VdbeAddOp3(v, OP_Ne, regResult+i, iJump, regPrev+i); - VdbeCoverage(v); - }else{ - sqlite3VdbeAddOp3(v, OP_Eq, regResult+i, iContinue, regPrev+i); - VdbeCoverage(v); - } - sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ); - sqlite3VdbeChangeP5(v, SQLITE_NULLEQ); - } - assert( sqlite3VdbeCurrentAddr(v)==iJump || pParse->db->mallocFailed ); - sqlite3VdbeAddOp3(v, OP_Copy, regResult, regPrev, nResultCol-1); - break; - } - - case WHERE_DISTINCT_UNIQUE: { - sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct); - break; - } - - default: { - assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED ); - codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol, - regResult); - break; - } - } - if( pSort==0 ){ - codeOffset(v, p->iOffset, iContinue); - } - } - - switch( eDest ){ - /* In this mode, write each query result to the key of the temporary - ** table iParm. - */ -#ifndef SQLITE_OMIT_COMPOUND_SELECT - case SRT_Union: { - int r1; - r1 = sqlite3GetTempReg(pParse); - sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1); - sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); - sqlite3ReleaseTempReg(pParse, r1); - break; - } - - /* Construct a record from the query result, but instead of - ** saving that record, use it as a key to delete elements from - ** the temporary table iParm. - */ - case SRT_Except: { - sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nResultCol); - break; - } -#endif /* SQLITE_OMIT_COMPOUND_SELECT */ - - /* Store the result as data using a unique key. - */ - case SRT_Fifo: - case SRT_DistFifo: - case SRT_Table: - case SRT_EphemTab: { - int r1 = sqlite3GetTempRange(pParse, nPrefixReg+1); - testcase( eDest==SRT_Table ); - testcase( eDest==SRT_EphemTab ); - testcase( eDest==SRT_Fifo ); - testcase( eDest==SRT_DistFifo ); - sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r1+nPrefixReg); -#ifndef SQLITE_OMIT_CTE - if( eDest==SRT_DistFifo ){ - /* If the destination is DistFifo, then cursor (iParm+1) is open - ** on an ephemeral index. If the current row is already present - ** in the index, do not write it to the output. If not, add the - ** current row to the index and proceed with writing it to the - ** output table as well. */ - int addr = sqlite3VdbeCurrentAddr(v) + 4; - sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0); - VdbeCoverage(v); - sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1); - assert( pSort==0 ); - } -#endif - if( pSort ){ - pushOntoSorter(pParse, pSort, p, r1+nPrefixReg,regResult,1,nPrefixReg); - }else{ - int r2 = sqlite3GetTempReg(pParse); - sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2); - sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2); - sqlite3VdbeChangeP5(v, OPFLAG_APPEND); - sqlite3ReleaseTempReg(pParse, r2); - } - sqlite3ReleaseTempRange(pParse, r1, nPrefixReg+1); - break; - } - -#ifndef SQLITE_OMIT_SUBQUERY - /* If we are creating a set for an "expr IN (SELECT ...)" construct, - ** then there should be a single item on the stack. Write this - ** item into the set table with bogus data. - */ - case SRT_Set: { - assert( nResultCol==1 ); - pDest->affSdst = - sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affSdst); - if( pSort ){ - /* At first glance you would think we could optimize out the - ** ORDER BY in this case since the order of entries in the set - ** does not matter. But there might be a LIMIT clause, in which - ** case the order does matter */ - pushOntoSorter(pParse, pSort, p, regResult, regResult, 1, nPrefixReg); - }else{ - int r1 = sqlite3GetTempReg(pParse); - sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult,1,r1, &pDest->affSdst, 1); - sqlite3ExprCacheAffinityChange(pParse, regResult, 1); - sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); - sqlite3ReleaseTempReg(pParse, r1); - } - break; - } - - /* If any row exist in the result set, record that fact and abort. - */ - case SRT_Exists: { - sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm); - /* The LIMIT clause will terminate the loop for us */ - break; - } - - /* If this is a scalar select that is part of an expression, then - ** store the results in the appropriate memory cell and break out - ** of the scan loop. - */ - case SRT_Mem: { - assert( nResultCol==1 ); - if( pSort ){ - pushOntoSorter(pParse, pSort, p, regResult, regResult, 1, nPrefixReg); - }else{ - assert( regResult==iParm ); - /* The LIMIT clause will jump out of the loop for us */ - } - break; - } -#endif /* #ifndef SQLITE_OMIT_SUBQUERY */ - - case SRT_Coroutine: /* Send data to a co-routine */ - case SRT_Output: { /* Return the results */ - testcase( eDest==SRT_Coroutine ); - testcase( eDest==SRT_Output ); - if( pSort ){ - pushOntoSorter(pParse, pSort, p, regResult, regResult, nResultCol, - nPrefixReg); - }else if( eDest==SRT_Coroutine ){ - sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm); - }else{ - sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nResultCol); - sqlite3ExprCacheAffinityChange(pParse, regResult, nResultCol); - } - break; - } - -#ifndef SQLITE_OMIT_CTE - /* Write the results into a priority queue that is order according to - ** pDest->pOrderBy (in pSO). pDest->iSDParm (in iParm) is the cursor for an - ** index with pSO->nExpr+2 columns. Build a key using pSO for the first - ** pSO->nExpr columns, then make sure all keys are unique by adding a - ** final OP_Sequence column. The last column is the record as a blob. - */ - case SRT_DistQueue: - case SRT_Queue: { - int nKey; - int r1, r2, r3; - int addrTest = 0; - ExprList *pSO; - pSO = pDest->pOrderBy; - assert( pSO ); - nKey = pSO->nExpr; - r1 = sqlite3GetTempReg(pParse); - r2 = sqlite3GetTempRange(pParse, nKey+2); - r3 = r2+nKey+1; - if( eDest==SRT_DistQueue ){ - /* If the destination is DistQueue, then cursor (iParm+1) is open - ** on a second ephemeral index that holds all values every previously - ** added to the queue. */ - addrTest = sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, 0, - regResult, nResultCol); - VdbeCoverage(v); - } - sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nResultCol, r3); - if( eDest==SRT_DistQueue ){ - sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r3); - sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT); - } - for(i=0; i<nKey; i++){ - sqlite3VdbeAddOp2(v, OP_SCopy, - regResult + pSO->a[i].u.x.iOrderByCol - 1, - r2+i); - } - sqlite3VdbeAddOp2(v, OP_Sequence, iParm, r2+nKey); - sqlite3VdbeAddOp3(v, OP_MakeRecord, r2, nKey+2, r1); - sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1); - if( addrTest ) sqlite3VdbeJumpHere(v, addrTest); - sqlite3ReleaseTempReg(pParse, r1); - sqlite3ReleaseTempRange(pParse, r2, nKey+2); - break; - } -#endif /* SQLITE_OMIT_CTE */ - - - -#if !defined(SQLITE_OMIT_TRIGGER) - /* Discard the results. This is used for SELECT statements inside - ** the body of a TRIGGER. The purpose of such selects is to call - ** user-defined functions that have side effects. We do not care - ** about the actual results of the select. - */ - default: { - assert( eDest==SRT_Discard ); - break; - } -#endif - } - - /* Jump to the end of the loop if the LIMIT is reached. Except, if - ** there is a sorter, in which case the sorter has already limited - ** the output for us. - */ - if( pSort==0 && p->iLimit ){ - sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v); - } -} - -/* -** Allocate a KeyInfo object sufficient for an index of N key columns and -** X extra columns. -*/ -KeyInfo *sqlite3KeyInfoAlloc(sqlite3 *db, int N, int X){ - KeyInfo *p = sqlite3DbMallocZero(0, - sizeof(KeyInfo) + (N+X)*(sizeof(CollSeq*)+1)); - if( p ){ - p->aSortOrder = (u8*)&p->aColl[N+X]; - p->nField = (u16)N; - p->nXField = (u16)X; - p->enc = ENC(db); - p->db = db; - p->nRef = 1; - }else{ - db->mallocFailed = 1; - } - return p; -} - -/* -** Deallocate a KeyInfo object -*/ -void sqlite3KeyInfoUnref(KeyInfo *p){ - if( p ){ - assert( p->nRef>0 ); - p->nRef--; - if( p->nRef==0 ) sqlite3DbFree(0, p); - } -} - -/* -** Make a new pointer to a KeyInfo object -*/ -KeyInfo *sqlite3KeyInfoRef(KeyInfo *p){ - if( p ){ - assert( p->nRef>0 ); - p->nRef++; - } - return p; -} - -#ifdef SQLITE_DEBUG -/* -** Return TRUE if a KeyInfo object can be change. The KeyInfo object -** can only be changed if this is just a single reference to the object. -** -** This routine is used only inside of assert() statements. -*/ -int sqlite3KeyInfoIsWriteable(KeyInfo *p){ return p->nRef==1; } -#endif /* SQLITE_DEBUG */ - -/* -** Given an expression list, generate a KeyInfo structure that records -** the collating sequence for each expression in that expression list. -** -** If the ExprList is an ORDER BY or GROUP BY clause then the resulting -** KeyInfo structure is appropriate for initializing a virtual index to -** implement that clause. If the ExprList is the result set of a SELECT -** then the KeyInfo structure is appropriate for initializing a virtual -** index to implement a DISTINCT test. -** -** Space to hold the KeyInfo structure is obtained from malloc. The calling -** function is responsible for seeing that this structure is eventually -** freed. -*/ -static KeyInfo *keyInfoFromExprList( - Parse *pParse, /* Parsing context */ - ExprList *pList, /* Form the KeyInfo object from this ExprList */ - int iStart, /* Begin with this column of pList */ - int nExtra /* Add this many extra columns to the end */ -){ - int nExpr; - KeyInfo *pInfo; - struct ExprList_item *pItem; - sqlite3 *db = pParse->db; - int i; - - nExpr = pList->nExpr; - pInfo = sqlite3KeyInfoAlloc(db, nExpr-iStart, nExtra+1); - if( pInfo ){ - assert( sqlite3KeyInfoIsWriteable(pInfo) ); - for(i=iStart, pItem=pList->a+iStart; i<nExpr; i++, pItem++){ - CollSeq *pColl; - pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr); - if( !pColl ) pColl = db->pDfltColl; - pInfo->aColl[i-iStart] = pColl; - pInfo->aSortOrder[i-iStart] = pItem->sortOrder; - } - } - return pInfo; -} - -/* -** Name of the connection operator, used for error messages. -*/ -static const char *selectOpName(int id){ - char *z; - switch( id ){ - case TK_ALL: z = "UNION ALL"; break; - case TK_INTERSECT: z = "INTERSECT"; break; - case TK_EXCEPT: z = "EXCEPT"; break; - default: z = "UNION"; break; - } - return z; -} - -#ifndef SQLITE_OMIT_EXPLAIN -/* -** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function -** is a no-op. Otherwise, it adds a single row of output to the EQP result, -** where the caption is of the form: -** -** "USE TEMP B-TREE FOR xxx" -** -** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which -** is determined by the zUsage argument. -*/ -static void explainTempTable(Parse *pParse, const char *zUsage){ - if( pParse->explain==2 ){ - Vdbe *v = pParse->pVdbe; - char *zMsg = sqlite3MPrintf(pParse->db, "USE TEMP B-TREE FOR %s", zUsage); - sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC); - } -} - -/* -** Assign expression b to lvalue a. A second, no-op, version of this macro -** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code -** in sqlite3Select() to assign values to structure member variables that -** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the -** code with #ifndef directives. -*/ -# define explainSetInteger(a, b) a = b - -#else -/* No-op versions of the explainXXX() functions and macros. */ -# define explainTempTable(y,z) -# define explainSetInteger(y,z) -#endif - -#if !defined(SQLITE_OMIT_EXPLAIN) && !defined(SQLITE_OMIT_COMPOUND_SELECT) -/* -** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function -** is a no-op. Otherwise, it adds a single row of output to the EQP result, -** where the caption is of one of the two forms: -** -** "COMPOSITE SUBQUERIES iSub1 and iSub2 (op)" -** "COMPOSITE SUBQUERIES iSub1 and iSub2 USING TEMP B-TREE (op)" -** -** where iSub1 and iSub2 are the integers passed as the corresponding -** function parameters, and op is the text representation of the parameter -** of the same name. The parameter "op" must be one of TK_UNION, TK_EXCEPT, -** TK_INTERSECT or TK_ALL. The first form is used if argument bUseTmp is -** false, or the second form if it is true. -*/ -static void explainComposite( - Parse *pParse, /* Parse context */ - int op, /* One of TK_UNION, TK_EXCEPT etc. */ - int iSub1, /* Subquery id 1 */ - int iSub2, /* Subquery id 2 */ - int bUseTmp /* True if a temp table was used */ -){ - assert( op==TK_UNION || op==TK_EXCEPT || op==TK_INTERSECT || op==TK_ALL ); - if( pParse->explain==2 ){ - Vdbe *v = pParse->pVdbe; - char *zMsg = sqlite3MPrintf( - pParse->db, "COMPOUND SUBQUERIES %d AND %d %s(%s)", iSub1, iSub2, - bUseTmp?"USING TEMP B-TREE ":"", selectOpName(op) - ); - sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC); - } -} -#else -/* No-op versions of the explainXXX() functions and macros. */ -# define explainComposite(v,w,x,y,z) -#endif - -/* -** If the inner loop was generated using a non-null pOrderBy argument, -** then the results were placed in a sorter. After the loop is terminated -** we need to run the sorter and output the results. The following -** routine generates the code needed to do that. -*/ -static void generateSortTail( - Parse *pParse, /* Parsing context */ - Select *p, /* The SELECT statement */ - SortCtx *pSort, /* Information on the ORDER BY clause */ - int nColumn, /* Number of columns of data */ - SelectDest *pDest /* Write the sorted results here */ -){ - Vdbe *v = pParse->pVdbe; /* The prepared statement */ - int addrBreak = sqlite3VdbeMakeLabel(v); /* Jump here to exit loop */ - int addrContinue = sqlite3VdbeMakeLabel(v); /* Jump here for next cycle */ - int addr; - int addrOnce = 0; - int iTab; - ExprList *pOrderBy = pSort->pOrderBy; - int eDest = pDest->eDest; - int iParm = pDest->iSDParm; - int regRow; - int regRowid; - int nKey; - int iSortTab; /* Sorter cursor to read from */ - int nSortData; /* Trailing values to read from sorter */ - int i; - int bSeq; /* True if sorter record includes seq. no. */ -#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS - struct ExprList_item *aOutEx = p->pEList->a; -#endif - - if( pSort->labelBkOut ){ - sqlite3VdbeAddOp2(v, OP_Gosub, pSort->regReturn, pSort->labelBkOut); - sqlite3VdbeGoto(v, addrBreak); - sqlite3VdbeResolveLabel(v, pSort->labelBkOut); - } - iTab = pSort->iECursor; - if( eDest==SRT_Output || eDest==SRT_Coroutine ){ - regRowid = 0; - regRow = pDest->iSdst; - nSortData = nColumn; - }else{ - regRowid = sqlite3GetTempReg(pParse); - regRow = sqlite3GetTempReg(pParse); - nSortData = 1; - } - nKey = pOrderBy->nExpr - pSort->nOBSat; - if( pSort->sortFlags & SORTFLAG_UseSorter ){ - int regSortOut = ++pParse->nMem; - iSortTab = pParse->nTab++; - if( pSort->labelBkOut ){ - addrOnce = sqlite3CodeOnce(pParse); VdbeCoverage(v); - } - sqlite3VdbeAddOp3(v, OP_OpenPseudo, iSortTab, regSortOut, nKey+1+nSortData); - if( addrOnce ) sqlite3VdbeJumpHere(v, addrOnce); - addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak); - VdbeCoverage(v); - codeOffset(v, p->iOffset, addrContinue); - sqlite3VdbeAddOp3(v, OP_SorterData, iTab, regSortOut, iSortTab); - bSeq = 0; - }else{ - addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak); VdbeCoverage(v); - codeOffset(v, p->iOffset, addrContinue); - iSortTab = iTab; - bSeq = 1; - } - for(i=0; i<nSortData; i++){ - sqlite3VdbeAddOp3(v, OP_Column, iSortTab, nKey+bSeq+i, regRow+i); - VdbeComment((v, "%s", aOutEx[i].zName ? aOutEx[i].zName : aOutEx[i].zSpan)); - } - switch( eDest ){ - case SRT_EphemTab: { - sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid); - sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid); - sqlite3VdbeChangeP5(v, OPFLAG_APPEND); - break; - } -#ifndef SQLITE_OMIT_SUBQUERY - case SRT_Set: { - assert( nColumn==1 ); - sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, 1, regRowid, - &pDest->affSdst, 1); - sqlite3ExprCacheAffinityChange(pParse, regRow, 1); - sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, regRowid); - break; - } - case SRT_Mem: { - assert( nColumn==1 ); - sqlite3ExprCodeMove(pParse, regRow, iParm, 1); - /* The LIMIT clause will terminate the loop for us */ - break; - } -#endif - default: { - assert( eDest==SRT_Output || eDest==SRT_Coroutine ); - testcase( eDest==SRT_Output ); - testcase( eDest==SRT_Coroutine ); - if( eDest==SRT_Output ){ - sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iSdst, nColumn); - sqlite3ExprCacheAffinityChange(pParse, pDest->iSdst, nColumn); - }else{ - sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm); - } - break; - } - } - if( regRowid ){ - sqlite3ReleaseTempReg(pParse, regRow); - sqlite3ReleaseTempReg(pParse, regRowid); - } - /* The bottom of the loop - */ - sqlite3VdbeResolveLabel(v, addrContinue); - if( pSort->sortFlags & SORTFLAG_UseSorter ){ - sqlite3VdbeAddOp2(v, OP_SorterNext, iTab, addr); VdbeCoverage(v); - }else{ - sqlite3VdbeAddOp2(v, OP_Next, iTab, addr); VdbeCoverage(v); - } - if( pSort->regReturn ) sqlite3VdbeAddOp1(v, OP_Return, pSort->regReturn); - sqlite3VdbeResolveLabel(v, addrBreak); -} - -/* -** Return a pointer to a string containing the 'declaration type' of the -** expression pExpr. The string may be treated as static by the caller. -** -** Also try to estimate the size of the returned value and return that -** result in *pEstWidth. -** -** The declaration type is the exact datatype definition extracted from the -** original CREATE TABLE statement if the expression is a column. The -** declaration type for a ROWID field is INTEGER. Exactly when an expression -** is considered a column can be complex in the presence of subqueries. The -** result-set expression in all of the following SELECT statements is -** considered a column by this function. -** -** SELECT col FROM tbl; -** SELECT (SELECT col FROM tbl; -** SELECT (SELECT col FROM tbl); -** SELECT abc FROM (SELECT col AS abc FROM tbl); -** -** The declaration type for any expression other than a column is NULL. -** -** This routine has either 3 or 6 parameters depending on whether or not -** the SQLITE_ENABLE_COLUMN_METADATA compile-time option is used. -*/ -#ifdef SQLITE_ENABLE_COLUMN_METADATA -# define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,C,D,E,F) -#else /* if !defined(SQLITE_ENABLE_COLUMN_METADATA) */ -# define columnType(A,B,C,D,E,F) columnTypeImpl(A,B,F) -#endif -static const char *columnTypeImpl( - NameContext *pNC, - Expr *pExpr, -#ifdef SQLITE_ENABLE_COLUMN_METADATA - const char **pzOrigDb, - const char **pzOrigTab, - const char **pzOrigCol, -#endif - u8 *pEstWidth -){ - char const *zType = 0; - int j; - u8 estWidth = 1; -#ifdef SQLITE_ENABLE_COLUMN_METADATA - char const *zOrigDb = 0; - char const *zOrigTab = 0; - char const *zOrigCol = 0; -#endif - - if( NEVER(pExpr==0) || pNC->pSrcList==0 ) return 0; - switch( pExpr->op ){ - case TK_AGG_COLUMN: - case TK_COLUMN: { - /* The expression is a column. Locate the table the column is being - ** extracted from in NameContext.pSrcList. This table may be real - ** database table or a subquery. - */ - Table *pTab = 0; /* Table structure column is extracted from */ - Select *pS = 0; /* Select the column is extracted from */ - int iCol = pExpr->iColumn; /* Index of column in pTab */ - testcase( pExpr->op==TK_AGG_COLUMN ); - testcase( pExpr->op==TK_COLUMN ); - while( pNC && !pTab ){ - SrcList *pTabList = pNC->pSrcList; - for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++); - if( j<pTabList->nSrc ){ - pTab = pTabList->a[j].pTab; - pS = pTabList->a[j].pSelect; - }else{ - pNC = pNC->pNext; - } - } - - if( pTab==0 ){ - /* At one time, code such as "SELECT new.x" within a trigger would - ** cause this condition to run. Since then, we have restructured how - ** trigger code is generated and so this condition is no longer - ** possible. However, it can still be true for statements like - ** the following: - ** - ** CREATE TABLE t1(col INTEGER); - ** SELECT (SELECT t1.col) FROM FROM t1; - ** - ** when columnType() is called on the expression "t1.col" in the - ** sub-select. In this case, set the column type to NULL, even - ** though it should really be "INTEGER". - ** - ** This is not a problem, as the column type of "t1.col" is never - ** used. When columnType() is called on the expression - ** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT - ** branch below. */ - break; - } - - assert( pTab && pExpr->pTab==pTab ); - if( pS ){ - /* The "table" is actually a sub-select or a view in the FROM clause - ** of the SELECT statement. Return the declaration type and origin - ** data for the result-set column of the sub-select. - */ - if( iCol>=0 && ALWAYS(iCol<pS->pEList->nExpr) ){ - /* If iCol is less than zero, then the expression requests the - ** rowid of the sub-select or view. This expression is legal (see - ** test case misc2.2.2) - it always evaluates to NULL. - ** - ** The ALWAYS() is because iCol>=pS->pEList->nExpr will have been - ** caught already by name resolution. - */ - NameContext sNC; - Expr *p = pS->pEList->a[iCol].pExpr; - sNC.pSrcList = pS->pSrc; - sNC.pNext = pNC; - sNC.pParse = pNC->pParse; - zType = columnType(&sNC, p,&zOrigDb,&zOrigTab,&zOrigCol, &estWidth); - } - }else if( pTab->pSchema ){ - /* A real table */ - assert( !pS ); - if( iCol<0 ) iCol = pTab->iPKey; - assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) ); -#ifdef SQLITE_ENABLE_COLUMN_METADATA - if( iCol<0 ){ - zType = "INTEGER"; - zOrigCol = "rowid"; - }else{ - zType = pTab->aCol[iCol].zType; - zOrigCol = pTab->aCol[iCol].zName; - estWidth = pTab->aCol[iCol].szEst; - } - zOrigTab = pTab->zName; - if( pNC->pParse ){ - int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema); - zOrigDb = pNC->pParse->db->aDb[iDb].zName; - } -#else - if( iCol<0 ){ - zType = "INTEGER"; - }else{ - zType = pTab->aCol[iCol].zType; - estWidth = pTab->aCol[iCol].szEst; - } -#endif - } - break; - } -#ifndef SQLITE_OMIT_SUBQUERY - case TK_SELECT: { - /* The expression is a sub-select. Return the declaration type and - ** origin info for the single column in the result set of the SELECT - ** statement. - */ - NameContext sNC; - Select *pS = pExpr->x.pSelect; - Expr *p = pS->pEList->a[0].pExpr; - assert( ExprHasProperty(pExpr, EP_xIsSelect) ); - sNC.pSrcList = pS->pSrc; - sNC.pNext = pNC; - sNC.pParse = pNC->pParse; - zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol, &estWidth); - break; - } -#endif - } - -#ifdef SQLITE_ENABLE_COLUMN_METADATA - if( pzOrigDb ){ - assert( pzOrigTab && pzOrigCol ); - *pzOrigDb = zOrigDb; - *pzOrigTab = zOrigTab; - *pzOrigCol = zOrigCol; - } -#endif - if( pEstWidth ) *pEstWidth = estWidth; - return zType; -} - -/* -** Generate code that will tell the VDBE the declaration types of columns -** in the result set. -*/ -static void generateColumnTypes( - Parse *pParse, /* Parser context */ - SrcList *pTabList, /* List of tables */ - ExprList *pEList /* Expressions defining the result set */ -){ -#ifndef SQLITE_OMIT_DECLTYPE - Vdbe *v = pParse->pVdbe; - int i; - NameContext sNC; - sNC.pSrcList = pTabList; - sNC.pParse = pParse; - for(i=0; i<pEList->nExpr; i++){ - Expr *p = pEList->a[i].pExpr; - const char *zType; -#ifdef SQLITE_ENABLE_COLUMN_METADATA - const char *zOrigDb = 0; - const char *zOrigTab = 0; - const char *zOrigCol = 0; - zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol, 0); - - /* The vdbe must make its own copy of the column-type and other - ** column specific strings, in case the schema is reset before this - ** virtual machine is deleted. - */ - sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, SQLITE_TRANSIENT); - sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, SQLITE_TRANSIENT); - sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, SQLITE_TRANSIENT); -#else - zType = columnType(&sNC, p, 0, 0, 0, 0); -#endif - sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT); - } -#endif /* !defined(SQLITE_OMIT_DECLTYPE) */ -} - -/* -** Generate code that will tell the VDBE the names of columns -** in the result set. This information is used to provide the -** azCol[] values in the callback. -*/ -static void generateColumnNames( - Parse *pParse, /* Parser context */ - SrcList *pTabList, /* List of tables */ - ExprList *pEList /* Expressions defining the result set */ -){ - Vdbe *v = pParse->pVdbe; - int i, j; - sqlite3 *db = pParse->db; - int fullNames, shortNames; - -#ifndef SQLITE_OMIT_EXPLAIN - /* If this is an EXPLAIN, skip this step */ - if( pParse->explain ){ - return; - } -#endif - - if( pParse->colNamesSet || NEVER(v==0) || db->mallocFailed ) return; - pParse->colNamesSet = 1; - fullNames = (db->flags & SQLITE_FullColNames)!=0; - shortNames = (db->flags & SQLITE_ShortColNames)!=0; - sqlite3VdbeSetNumCols(v, pEList->nExpr); - for(i=0; i<pEList->nExpr; i++){ - Expr *p; - p = pEList->a[i].pExpr; - if( NEVER(p==0) ) continue; - if( pEList->a[i].zName ){ - char *zName = pEList->a[i].zName; - sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT); - }else if( (p->op==TK_COLUMN || p->op==TK_AGG_COLUMN) && pTabList ){ - Table *pTab; - char *zCol; - int iCol = p->iColumn; - for(j=0; ALWAYS(j<pTabList->nSrc); j++){ - if( pTabList->a[j].iCursor==p->iTable ) break; - } - assert( j<pTabList->nSrc ); - pTab = pTabList->a[j].pTab; - if( iCol<0 ) iCol = pTab->iPKey; - assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) ); - if( iCol<0 ){ - zCol = "rowid"; - }else{ - zCol = pTab->aCol[iCol].zName; - } - if( !shortNames && !fullNames ){ - sqlite3VdbeSetColName(v, i, COLNAME_NAME, - sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC); - }else if( fullNames ){ - char *zName = 0; - zName = sqlite3MPrintf(db, "%s.%s", pTab->zName, zCol); - sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC); - }else{ - sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, SQLITE_TRANSIENT); - } - }else{ - const char *z = pEList->a[i].zSpan; - z = z==0 ? sqlite3MPrintf(db, "column%d", i+1) : sqlite3DbStrDup(db, z); - sqlite3VdbeSetColName(v, i, COLNAME_NAME, z, SQLITE_DYNAMIC); - } - } - generateColumnTypes(pParse, pTabList, pEList); -} - -/* -** Given an expression list (which is really the list of expressions -** that form the result set of a SELECT statement) compute appropriate -** column names for a table that would hold the expression list. -** -** All column names will be unique. -** -** Only the column names are computed. Column.zType, Column.zColl, -** and other fields of Column are zeroed. -** -** Return SQLITE_OK on success. If a memory allocation error occurs, -** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM. -*/ -int sqlite3ColumnsFromExprList( - Parse *pParse, /* Parsing context */ - ExprList *pEList, /* Expr list from which to derive column names */ - i16 *pnCol, /* Write the number of columns here */ - Column **paCol /* Write the new column list here */ -){ - sqlite3 *db = pParse->db; /* Database connection */ - int i, j; /* Loop counters */ - int cnt; /* Index added to make the name unique */ - Column *aCol, *pCol; /* For looping over result columns */ - int nCol; /* Number of columns in the result set */ - Expr *p; /* Expression for a single result column */ - char *zName; /* Column name */ - int nName; /* Size of name in zName[] */ - - if( pEList ){ - nCol = pEList->nExpr; - aCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol); - testcase( aCol==0 ); - }else{ - nCol = 0; - aCol = 0; - } - *pnCol = nCol; - *paCol = aCol; - - for(i=0, pCol=aCol; i<nCol; i++, pCol++){ - /* Get an appropriate name for the column - */ - p = sqlite3ExprSkipCollate(pEList->a[i].pExpr); - if( (zName = pEList->a[i].zName)!=0 ){ - /* If the column contains an "AS <name>" phrase, use <name> as the name */ - zName = sqlite3DbStrDup(db, zName); - }else{ - Expr *pColExpr = p; /* The expression that is the result column name */ - Table *pTab; /* Table associated with this expression */ - while( pColExpr->op==TK_DOT ){ - pColExpr = pColExpr->pRight; - assert( pColExpr!=0 ); - } - if( pColExpr->op==TK_COLUMN && ALWAYS(pColExpr->pTab!=0) ){ - /* For columns use the column name name */ - int iCol = pColExpr->iColumn; - pTab = pColExpr->pTab; - if( iCol<0 ) iCol = pTab->iPKey; - zName = sqlite3MPrintf(db, "%s", - iCol>=0 ? pTab->aCol[iCol].zName : "rowid"); - }else if( pColExpr->op==TK_ID ){ - assert( !ExprHasProperty(pColExpr, EP_IntValue) ); - zName = sqlite3MPrintf(db, "%s", pColExpr->u.zToken); - }else{ - /* Use the original text of the column expression as its name */ - zName = sqlite3MPrintf(db, "%s", pEList->a[i].zSpan); - } - } - if( db->mallocFailed ){ - sqlite3DbFree(db, zName); - break; - } - - /* Make sure the column name is unique. If the name is not unique, - ** append an integer to the name so that it becomes unique. - */ - nName = sqlite3Strlen30(zName); - for(j=cnt=0; j<i; j++){ - if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){ - char *zNewName; - int k; - for(k=nName-1; k>1 && sqlite3Isdigit(zName[k]); k--){} - if( k>=0 && zName[k]==':' ) nName = k; - zName[nName] = 0; - zNewName = sqlite3MPrintf(db, "%s:%d", zName, ++cnt); - sqlite3DbFree(db, zName); - zName = zNewName; - j = -1; - if( zName==0 ) break; - } - } - pCol->zName = zName; - } - if( db->mallocFailed ){ - for(j=0; j<i; j++){ - sqlite3DbFree(db, aCol[j].zName); - } - sqlite3DbFree(db, aCol); - *paCol = 0; - *pnCol = 0; - return SQLITE_NOMEM; - } - return SQLITE_OK; -} - -/* -** Add type and collation information to a column list based on -** a SELECT statement. -** -** The column list presumably came from selectColumnNamesFromExprList(). -** The column list has only names, not types or collations. This -** routine goes through and adds the types and collations. -** -** This routine requires that all identifiers in the SELECT -** statement be resolved. -*/ -static void selectAddColumnTypeAndCollation( - Parse *pParse, /* Parsing contexts */ - Table *pTab, /* Add column type information to this table */ - Select *pSelect /* SELECT used to determine types and collations */ -){ - sqlite3 *db = pParse->db; - NameContext sNC; - Column *pCol; - CollSeq *pColl; - int i; - Expr *p; - struct ExprList_item *a; - u64 szAll = 0; - - assert( pSelect!=0 ); - assert( (pSelect->selFlags & SF_Resolved)!=0 ); - assert( pTab->nCol==pSelect->pEList->nExpr || db->mallocFailed ); - if( db->mallocFailed ) return; - memset(&sNC, 0, sizeof(sNC)); - sNC.pSrcList = pSelect->pSrc; - a = pSelect->pEList->a; - for(i=0, pCol=pTab->aCol; i<pTab->nCol; i++, pCol++){ - p = a[i].pExpr; - if( pCol->zType==0 ){ - pCol->zType = sqlite3DbStrDup(db, - columnType(&sNC, p,0,0,0, &pCol->szEst)); - } - szAll += pCol->szEst; - pCol->affinity = sqlite3ExprAffinity(p); - if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_BLOB; - pColl = sqlite3ExprCollSeq(pParse, p); - if( pColl && pCol->zColl==0 ){ - pCol->zColl = sqlite3DbStrDup(db, pColl->zName); - } - } - pTab->szTabRow = sqlite3LogEst(szAll*4); -} - -/* -** Given a SELECT statement, generate a Table structure that describes -** the result set of that SELECT. -*/ -Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){ - Table *pTab; - sqlite3 *db = pParse->db; - int savedFlags; - - savedFlags = db->flags; - db->flags &= ~SQLITE_FullColNames; - db->flags |= SQLITE_ShortColNames; - sqlite3SelectPrep(pParse, pSelect, 0); - if( pParse->nErr ) return 0; - while( pSelect->pPrior ) pSelect = pSelect->pPrior; - db->flags = savedFlags; - pTab = sqlite3DbMallocZero(db, sizeof(Table) ); - if( pTab==0 ){ - return 0; - } - /* The sqlite3ResultSetOfSelect() is only used n contexts where lookaside - ** is disabled */ - assert( db->lookaside.bEnabled==0 ); - pTab->nRef = 1; - pTab->zName = 0; - pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) ); - sqlite3ColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol); - selectAddColumnTypeAndCollation(pParse, pTab, pSelect); - pTab->iPKey = -1; - if( db->mallocFailed ){ - sqlite3DeleteTable(db, pTab); - return 0; - } - return pTab; -} - -/* -** Get a VDBE for the given parser context. Create a new one if necessary. -** If an error occurs, return NULL and leave a message in pParse. -*/ -Vdbe *sqlite3GetVdbe(Parse *pParse){ - Vdbe *v = pParse->pVdbe; - if( v==0 ){ - v = pParse->pVdbe = sqlite3VdbeCreate(pParse); - if( v ) sqlite3VdbeAddOp0(v, OP_Init); - if( pParse->pToplevel==0 - && OptimizationEnabled(pParse->db,SQLITE_FactorOutConst) - ){ - pParse->okConstFactor = 1; - } - - } - return v; -} - - -/* -** Compute the iLimit and iOffset fields of the SELECT based on the -** pLimit and pOffset expressions. pLimit and pOffset hold the expressions -** that appear in the original SQL statement after the LIMIT and OFFSET -** keywords. Or NULL if those keywords are omitted. iLimit and iOffset -** are the integer memory register numbers for counters used to compute -** the limit and offset. If there is no limit and/or offset, then -** iLimit and iOffset are negative. -** -** This routine changes the values of iLimit and iOffset only if -** a limit or offset is defined by pLimit and pOffset. iLimit and -** iOffset should have been preset to appropriate default values (zero) -** prior to calling this routine. -** -** The iOffset register (if it exists) is initialized to the value -** of the OFFSET. The iLimit register is initialized to LIMIT. Register -** iOffset+1 is initialized to LIMIT+OFFSET. -** -** Only if pLimit!=0 or pOffset!=0 do the limit registers get -** redefined. The UNION ALL operator uses this property to force -** the reuse of the same limit and offset registers across multiple -** SELECT statements. -*/ -static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){ - Vdbe *v = 0; - int iLimit = 0; - int iOffset; - int n; - if( p->iLimit ) return; - - /* - ** "LIMIT -1" always shows all rows. There is some - ** controversy about what the correct behavior should be. - ** The current implementation interprets "LIMIT 0" to mean - ** no rows. - */ - sqlite3ExprCacheClear(pParse); - assert( p->pOffset==0 || p->pLimit!=0 ); - if( p->pLimit ){ - p->iLimit = iLimit = ++pParse->nMem; - v = sqlite3GetVdbe(pParse); - assert( v!=0 ); - if( sqlite3ExprIsInteger(p->pLimit, &n) ){ - sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit); - VdbeComment((v, "LIMIT counter")); - if( n==0 ){ - sqlite3VdbeGoto(v, iBreak); - }else if( n>=0 && p->nSelectRow>(u64)n ){ - p->nSelectRow = n; - } - }else{ - sqlite3ExprCode(pParse, p->pLimit, iLimit); - sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); VdbeCoverage(v); - VdbeComment((v, "LIMIT counter")); - sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, iBreak); VdbeCoverage(v); - } - if( p->pOffset ){ - p->iOffset = iOffset = ++pParse->nMem; - pParse->nMem++; /* Allocate an extra register for limit+offset */ - sqlite3ExprCode(pParse, p->pOffset, iOffset); - sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset); VdbeCoverage(v); - VdbeComment((v, "OFFSET counter")); - sqlite3VdbeAddOp3(v, OP_SetIfNotPos, iOffset, iOffset, 0); - sqlite3VdbeAddOp3(v, OP_Add, iLimit, iOffset, iOffset+1); - VdbeComment((v, "LIMIT+OFFSET")); - sqlite3VdbeAddOp3(v, OP_SetIfNotPos, iLimit, iOffset+1, -1); - } - } -} - -#ifndef SQLITE_OMIT_COMPOUND_SELECT -/* -** Return the appropriate collating sequence for the iCol-th column of -** the result set for the compound-select statement "p". Return NULL if -** the column has no default collating sequence. -** -** The collating sequence for the compound select is taken from the -** left-most term of the select that has a collating sequence. -*/ -static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){ - CollSeq *pRet; - if( p->pPrior ){ - pRet = multiSelectCollSeq(pParse, p->pPrior, iCol); - }else{ - pRet = 0; - } - assert( iCol>=0 ); - /* iCol must be less than p->pEList->nExpr. Otherwise an error would - ** have been thrown during name resolution and we would not have gotten - ** this far */ - if( pRet==0 && ALWAYS(iCol<p->pEList->nExpr) ){ - pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr); - } - return pRet; -} - -/* -** The select statement passed as the second parameter is a compound SELECT -** with an ORDER BY clause. This function allocates and returns a KeyInfo -** structure suitable for implementing the ORDER BY. -** -** Space to hold the KeyInfo structure is obtained from malloc. The calling -** function is responsible for ensuring that this structure is eventually -** freed. -*/ -static KeyInfo *multiSelectOrderByKeyInfo(Parse *pParse, Select *p, int nExtra){ - ExprList *pOrderBy = p->pOrderBy; - int nOrderBy = p->pOrderBy->nExpr; - sqlite3 *db = pParse->db; - KeyInfo *pRet = sqlite3KeyInfoAlloc(db, nOrderBy+nExtra, 1); - if( pRet ){ - int i; - for(i=0; i<nOrderBy; i++){ - struct ExprList_item *pItem = &pOrderBy->a[i]; - Expr *pTerm = pItem->pExpr; - CollSeq *pColl; - - if( pTerm->flags & EP_Collate ){ - pColl = sqlite3ExprCollSeq(pParse, pTerm); - }else{ - pColl = multiSelectCollSeq(pParse, p, pItem->u.x.iOrderByCol-1); - if( pColl==0 ) pColl = db->pDfltColl; - pOrderBy->a[i].pExpr = - sqlite3ExprAddCollateString(pParse, pTerm, pColl->zName); - } - assert( sqlite3KeyInfoIsWriteable(pRet) ); - pRet->aColl[i] = pColl; - pRet->aSortOrder[i] = pOrderBy->a[i].sortOrder; - } - } - - return pRet; -} - -#ifndef SQLITE_OMIT_CTE -/* -** This routine generates VDBE code to compute the content of a WITH RECURSIVE -** query of the form: -** -** <recursive-table> AS (<setup-query> UNION [ALL] <recursive-query>) -** \___________/ \_______________/ -** p->pPrior p -** -** -** There is exactly one reference to the recursive-table in the FROM clause -** of recursive-query, marked with the SrcList->a[].fg.isRecursive flag. -** -** The setup-query runs once to generate an initial set of rows that go -** into a Queue table. Rows are extracted from the Queue table one by -** one. Each row extracted from Queue is output to pDest. Then the single -** extracted row (now in the iCurrent table) becomes the content of the -** recursive-table for a recursive-query run. The output of the recursive-query -** is added back into the Queue table. Then another row is extracted from Queue -** and the iteration continues until the Queue table is empty. -** -** If the compound query operator is UNION then no duplicate rows are ever -** inserted into the Queue table. The iDistinct table keeps a copy of all rows -** that have ever been inserted into Queue and causes duplicates to be -** discarded. If the operator is UNION ALL, then duplicates are allowed. -** -** If the query has an ORDER BY, then entries in the Queue table are kept in -** ORDER BY order and the first entry is extracted for each cycle. Without -** an ORDER BY, the Queue table is just a FIFO. -** -** If a LIMIT clause is provided, then the iteration stops after LIMIT rows -** have been output to pDest. A LIMIT of zero means to output no rows and a -** negative LIMIT means to output all rows. If there is also an OFFSET clause -** with a positive value, then the first OFFSET outputs are discarded rather -** than being sent to pDest. The LIMIT count does not begin until after OFFSET -** rows have been skipped. -*/ -static void generateWithRecursiveQuery( - Parse *pParse, /* Parsing context */ - Select *p, /* The recursive SELECT to be coded */ - SelectDest *pDest /* What to do with query results */ -){ - SrcList *pSrc = p->pSrc; /* The FROM clause of the recursive query */ - int nCol = p->pEList->nExpr; /* Number of columns in the recursive table */ - Vdbe *v = pParse->pVdbe; /* The prepared statement under construction */ - Select *pSetup = p->pPrior; /* The setup query */ - int addrTop; /* Top of the loop */ - int addrCont, addrBreak; /* CONTINUE and BREAK addresses */ - int iCurrent = 0; /* The Current table */ - int regCurrent; /* Register holding Current table */ - int iQueue; /* The Queue table */ - int iDistinct = 0; /* To ensure unique results if UNION */ - int eDest = SRT_Fifo; /* How to write to Queue */ - SelectDest destQueue; /* SelectDest targetting the Queue table */ - int i; /* Loop counter */ - int rc; /* Result code */ - ExprList *pOrderBy; /* The ORDER BY clause */ - Expr *pLimit, *pOffset; /* Saved LIMIT and OFFSET */ - int regLimit, regOffset; /* Registers used by LIMIT and OFFSET */ - - /* Obtain authorization to do a recursive query */ - if( sqlite3AuthCheck(pParse, SQLITE_RECURSIVE, 0, 0, 0) ) return; - - /* Process the LIMIT and OFFSET clauses, if they exist */ - addrBreak = sqlite3VdbeMakeLabel(v); - computeLimitRegisters(pParse, p, addrBreak); - pLimit = p->pLimit; - pOffset = p->pOffset; - regLimit = p->iLimit; - regOffset = p->iOffset; - p->pLimit = p->pOffset = 0; - p->iLimit = p->iOffset = 0; - pOrderBy = p->pOrderBy; - - /* Locate the cursor number of the Current table */ - for(i=0; ALWAYS(i<pSrc->nSrc); i++){ - if( pSrc->a[i].fg.isRecursive ){ - iCurrent = pSrc->a[i].iCursor; - break; - } - } - - /* Allocate cursors numbers for Queue and Distinct. The cursor number for - ** the Distinct table must be exactly one greater than Queue in order - ** for the SRT_DistFifo and SRT_DistQueue destinations to work. */ - iQueue = pParse->nTab++; - if( p->op==TK_UNION ){ - eDest = pOrderBy ? SRT_DistQueue : SRT_DistFifo; - iDistinct = pParse->nTab++; - }else{ - eDest = pOrderBy ? SRT_Queue : SRT_Fifo; - } - sqlite3SelectDestInit(&destQueue, eDest, iQueue); - - /* Allocate cursors for Current, Queue, and Distinct. */ - regCurrent = ++pParse->nMem; - sqlite3VdbeAddOp3(v, OP_OpenPseudo, iCurrent, regCurrent, nCol); - if( pOrderBy ){ - KeyInfo *pKeyInfo = multiSelectOrderByKeyInfo(pParse, p, 1); - sqlite3VdbeAddOp4(v, OP_OpenEphemeral, iQueue, pOrderBy->nExpr+2, 0, - (char*)pKeyInfo, P4_KEYINFO); - destQueue.pOrderBy = pOrderBy; - }else{ - sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iQueue, nCol); - } - VdbeComment((v, "Queue table")); - if( iDistinct ){ - p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iDistinct, 0); - p->selFlags |= SF_UsesEphemeral; - } - - /* Detach the ORDER BY clause from the compound SELECT */ - p->pOrderBy = 0; - - /* Store the results of the setup-query in Queue. */ - pSetup->pNext = 0; - rc = sqlite3Select(pParse, pSetup, &destQueue); - pSetup->pNext = p; - if( rc ) goto end_of_recursive_query; - - /* Find the next row in the Queue and output that row */ - addrTop = sqlite3VdbeAddOp2(v, OP_Rewind, iQueue, addrBreak); VdbeCoverage(v); - - /* Transfer the next row in Queue over to Current */ - sqlite3VdbeAddOp1(v, OP_NullRow, iCurrent); /* To reset column cache */ - if( pOrderBy ){ - sqlite3VdbeAddOp3(v, OP_Column, iQueue, pOrderBy->nExpr+1, regCurrent); - }else{ - sqlite3VdbeAddOp2(v, OP_RowData, iQueue, regCurrent); - } - sqlite3VdbeAddOp1(v, OP_Delete, iQueue); - - /* Output the single row in Current */ - addrCont = sqlite3VdbeMakeLabel(v); - codeOffset(v, regOffset, addrCont); - selectInnerLoop(pParse, p, p->pEList, iCurrent, - 0, 0, pDest, addrCont, addrBreak); - if( regLimit ){ - sqlite3VdbeAddOp2(v, OP_DecrJumpZero, regLimit, addrBreak); - VdbeCoverage(v); - } - sqlite3VdbeResolveLabel(v, addrCont); - - /* Execute the recursive SELECT taking the single row in Current as - ** the value for the recursive-table. Store the results in the Queue. - */ - if( p->selFlags & SF_Aggregate ){ - sqlite3ErrorMsg(pParse, "recursive aggregate queries not supported"); - }else{ - p->pPrior = 0; - sqlite3Select(pParse, p, &destQueue); - assert( p->pPrior==0 ); - p->pPrior = pSetup; - } - - /* Keep running the loop until the Queue is empty */ - sqlite3VdbeGoto(v, addrTop); - sqlite3VdbeResolveLabel(v, addrBreak); - -end_of_recursive_query: - sqlite3ExprListDelete(pParse->db, p->pOrderBy); - p->pOrderBy = pOrderBy; - p->pLimit = pLimit; - p->pOffset = pOffset; - return; -} -#endif /* SQLITE_OMIT_CTE */ - -/* Forward references */ -static int multiSelectOrderBy( - Parse *pParse, /* Parsing context */ - Select *p, /* The right-most of SELECTs to be coded */ - SelectDest *pDest /* What to do with query results */ -); - -/* -** Handle the special case of a compound-select that originates from a -** VALUES clause. By handling this as a special case, we avoid deep -** recursion, and thus do not need to enforce the SQLITE_LIMIT_COMPOUND_SELECT -** on a VALUES clause. -** -** Because the Select object originates from a VALUES clause: -** (1) It has no LIMIT or OFFSET -** (2) All terms are UNION ALL -** (3) There is no ORDER BY clause -*/ -static int multiSelectValues( - Parse *pParse, /* Parsing context */ - Select *p, /* The right-most of SELECTs to be coded */ - SelectDest *pDest /* What to do with query results */ -){ - Select *pPrior; - int nRow = 1; - int rc = 0; - assert( p->selFlags & SF_MultiValue ); - do{ - assert( p->selFlags & SF_Values ); - assert( p->op==TK_ALL || (p->op==TK_SELECT && p->pPrior==0) ); - assert( p->pLimit==0 ); - assert( p->pOffset==0 ); - assert( p->pNext==0 || p->pEList->nExpr==p->pNext->pEList->nExpr ); - if( p->pPrior==0 ) break; - assert( p->pPrior->pNext==p ); - p = p->pPrior; - nRow++; - }while(1); - while( p ){ - pPrior = p->pPrior; - p->pPrior = 0; - rc = sqlite3Select(pParse, p, pDest); - p->pPrior = pPrior; - if( rc ) break; - p->nSelectRow = nRow; - p = p->pNext; - } - return rc; -} - -/* -** This routine is called to process a compound query form from -** two or more separate queries using UNION, UNION ALL, EXCEPT, or -** INTERSECT -** -** "p" points to the right-most of the two queries. the query on the -** left is p->pPrior. The left query could also be a compound query -** in which case this routine will be called recursively. -** -** The results of the total query are to be written into a destination -** of type eDest with parameter iParm. -** -** Example 1: Consider a three-way compound SQL statement. -** -** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3 -** -** This statement is parsed up as follows: -** -** SELECT c FROM t3 -** | -** `-----> SELECT b FROM t2 -** | -** `------> SELECT a FROM t1 -** -** The arrows in the diagram above represent the Select.pPrior pointer. -** So if this routine is called with p equal to the t3 query, then -** pPrior will be the t2 query. p->op will be TK_UNION in this case. -** -** Notice that because of the way SQLite parses compound SELECTs, the -** individual selects always group from left to right. -*/ -static int multiSelect( - Parse *pParse, /* Parsing context */ - Select *p, /* The right-most of SELECTs to be coded */ - SelectDest *pDest /* What to do with query results */ -){ - int rc = SQLITE_OK; /* Success code from a subroutine */ - Select *pPrior; /* Another SELECT immediately to our left */ - Vdbe *v; /* Generate code to this VDBE */ - SelectDest dest; /* Alternative data destination */ - Select *pDelete = 0; /* Chain of simple selects to delete */ - sqlite3 *db; /* Database connection */ -#ifndef SQLITE_OMIT_EXPLAIN - int iSub1 = 0; /* EQP id of left-hand query */ - int iSub2 = 0; /* EQP id of right-hand query */ -#endif - - /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only - ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT. - */ - assert( p && p->pPrior ); /* Calling function guarantees this much */ - assert( (p->selFlags & SF_Recursive)==0 || p->op==TK_ALL || p->op==TK_UNION ); - db = pParse->db; - pPrior = p->pPrior; - dest = *pDest; - if( pPrior->pOrderBy ){ - sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before", - selectOpName(p->op)); - rc = 1; - goto multi_select_end; - } - if( pPrior->pLimit ){ - sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before", - selectOpName(p->op)); - rc = 1; - goto multi_select_end; - } - - v = sqlite3GetVdbe(pParse); - assert( v!=0 ); /* The VDBE already created by calling function */ - - /* Create the destination temporary table if necessary - */ - if( dest.eDest==SRT_EphemTab ){ - assert( p->pEList ); - sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iSDParm, p->pEList->nExpr); - sqlite3VdbeChangeP5(v, BTREE_UNORDERED); - dest.eDest = SRT_Table; - } - - /* Special handling for a compound-select that originates as a VALUES clause. - */ - if( p->selFlags & SF_MultiValue ){ - rc = multiSelectValues(pParse, p, &dest); - goto multi_select_end; - } - - /* Make sure all SELECTs in the statement have the same number of elements - ** in their result sets. - */ - assert( p->pEList && pPrior->pEList ); - assert( p->pEList->nExpr==pPrior->pEList->nExpr ); - -#ifndef SQLITE_OMIT_CTE - if( p->selFlags & SF_Recursive ){ - generateWithRecursiveQuery(pParse, p, &dest); - }else -#endif - - /* Compound SELECTs that have an ORDER BY clause are handled separately. - */ - if( p->pOrderBy ){ - return multiSelectOrderBy(pParse, p, pDest); - }else - - /* Generate code for the left and right SELECT statements. - */ - switch( p->op ){ - case TK_ALL: { - int addr = 0; - int nLimit; - assert( !pPrior->pLimit ); - pPrior->iLimit = p->iLimit; - pPrior->iOffset = p->iOffset; - pPrior->pLimit = p->pLimit; - pPrior->pOffset = p->pOffset; - explainSetInteger(iSub1, pParse->iNextSelectId); - rc = sqlite3Select(pParse, pPrior, &dest); - p->pLimit = 0; - p->pOffset = 0; - if( rc ){ - goto multi_select_end; - } - p->pPrior = 0; - p->iLimit = pPrior->iLimit; - p->iOffset = pPrior->iOffset; - if( p->iLimit ){ - addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v); - VdbeComment((v, "Jump ahead if LIMIT reached")); - if( p->iOffset ){ - sqlite3VdbeAddOp3(v, OP_SetIfNotPos, p->iOffset, p->iOffset, 0); - sqlite3VdbeAddOp3(v, OP_Add, p->iLimit, p->iOffset, p->iOffset+1); - sqlite3VdbeAddOp3(v, OP_SetIfNotPos, p->iLimit, p->iOffset+1, -1); - } - } - explainSetInteger(iSub2, pParse->iNextSelectId); - rc = sqlite3Select(pParse, p, &dest); - testcase( rc!=SQLITE_OK ); - pDelete = p->pPrior; - p->pPrior = pPrior; - p->nSelectRow += pPrior->nSelectRow; - if( pPrior->pLimit - && sqlite3ExprIsInteger(pPrior->pLimit, &nLimit) - && nLimit>0 && p->nSelectRow > (u64)nLimit - ){ - p->nSelectRow = nLimit; - } - if( addr ){ - sqlite3VdbeJumpHere(v, addr); - } - break; - } - case TK_EXCEPT: - case TK_UNION: { - int unionTab; /* Cursor number of the temporary table holding result */ - u8 op = 0; /* One of the SRT_ operations to apply to self */ - int priorOp; /* The SRT_ operation to apply to prior selects */ - Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */ - int addr; - SelectDest uniondest; - - testcase( p->op==TK_EXCEPT ); - testcase( p->op==TK_UNION ); - priorOp = SRT_Union; - if( dest.eDest==priorOp ){ - /* We can reuse a temporary table generated by a SELECT to our - ** right. - */ - assert( p->pLimit==0 ); /* Not allowed on leftward elements */ - assert( p->pOffset==0 ); /* Not allowed on leftward elements */ - unionTab = dest.iSDParm; - }else{ - /* We will need to create our own temporary table to hold the - ** intermediate results. - */ - unionTab = pParse->nTab++; - assert( p->pOrderBy==0 ); - addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0); - assert( p->addrOpenEphm[0] == -1 ); - p->addrOpenEphm[0] = addr; - findRightmost(p)->selFlags |= SF_UsesEphemeral; - assert( p->pEList ); - } - - /* Code the SELECT statements to our left - */ - assert( !pPrior->pOrderBy ); - sqlite3SelectDestInit(&uniondest, priorOp, unionTab); - explainSetInteger(iSub1, pParse->iNextSelectId); - rc = sqlite3Select(pParse, pPrior, &uniondest); - if( rc ){ - goto multi_select_end; - } - - /* Code the current SELECT statement - */ - if( p->op==TK_EXCEPT ){ - op = SRT_Except; - }else{ - assert( p->op==TK_UNION ); - op = SRT_Union; - } - p->pPrior = 0; - pLimit = p->pLimit; - p->pLimit = 0; - pOffset = p->pOffset; - p->pOffset = 0; - uniondest.eDest = op; - explainSetInteger(iSub2, pParse->iNextSelectId); - rc = sqlite3Select(pParse, p, &uniondest); - testcase( rc!=SQLITE_OK ); - /* Query flattening in sqlite3Select() might refill p->pOrderBy. - ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */ - sqlite3ExprListDelete(db, p->pOrderBy); - pDelete = p->pPrior; - p->pPrior = pPrior; - p->pOrderBy = 0; - if( p->op==TK_UNION ) p->nSelectRow += pPrior->nSelectRow; - sqlite3ExprDelete(db, p->pLimit); - p->pLimit = pLimit; - p->pOffset = pOffset; - p->iLimit = 0; - p->iOffset = 0; - - /* Convert the data in the temporary table into whatever form - ** it is that we currently need. - */ - assert( unionTab==dest.iSDParm || dest.eDest!=priorOp ); - if( dest.eDest!=priorOp ){ - int iCont, iBreak, iStart; - assert( p->pEList ); - if( dest.eDest==SRT_Output ){ - Select *pFirst = p; - while( pFirst->pPrior ) pFirst = pFirst->pPrior; - generateColumnNames(pParse, 0, pFirst->pEList); - } - iBreak = sqlite3VdbeMakeLabel(v); - iCont = sqlite3VdbeMakeLabel(v); - computeLimitRegisters(pParse, p, iBreak); - sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak); VdbeCoverage(v); - iStart = sqlite3VdbeCurrentAddr(v); - selectInnerLoop(pParse, p, p->pEList, unionTab, - 0, 0, &dest, iCont, iBreak); - sqlite3VdbeResolveLabel(v, iCont); - sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart); VdbeCoverage(v); - sqlite3VdbeResolveLabel(v, iBreak); - sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0); - } - break; - } - default: assert( p->op==TK_INTERSECT ); { - int tab1, tab2; - int iCont, iBreak, iStart; - Expr *pLimit, *pOffset; - int addr; - SelectDest intersectdest; - int r1; - - /* INTERSECT is different from the others since it requires - ** two temporary tables. Hence it has its own case. Begin - ** by allocating the tables we will need. - */ - tab1 = pParse->nTab++; - tab2 = pParse->nTab++; - assert( p->pOrderBy==0 ); - - addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0); - assert( p->addrOpenEphm[0] == -1 ); - p->addrOpenEphm[0] = addr; - findRightmost(p)->selFlags |= SF_UsesEphemeral; - assert( p->pEList ); - - /* Code the SELECTs to our left into temporary table "tab1". - */ - sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1); - explainSetInteger(iSub1, pParse->iNextSelectId); - rc = sqlite3Select(pParse, pPrior, &intersectdest); - if( rc ){ - goto multi_select_end; - } - - /* Code the current SELECT into temporary table "tab2" - */ - addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0); - assert( p->addrOpenEphm[1] == -1 ); - p->addrOpenEphm[1] = addr; - p->pPrior = 0; - pLimit = p->pLimit; - p->pLimit = 0; - pOffset = p->pOffset; - p->pOffset = 0; - intersectdest.iSDParm = tab2; - explainSetInteger(iSub2, pParse->iNextSelectId); - rc = sqlite3Select(pParse, p, &intersectdest); - testcase( rc!=SQLITE_OK ); - pDelete = p->pPrior; - p->pPrior = pPrior; - if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow; - sqlite3ExprDelete(db, p->pLimit); - p->pLimit = pLimit; - p->pOffset = pOffset; - - /* Generate code to take the intersection of the two temporary - ** tables. - */ - assert( p->pEList ); - if( dest.eDest==SRT_Output ){ - Select *pFirst = p; - while( pFirst->pPrior ) pFirst = pFirst->pPrior; - generateColumnNames(pParse, 0, pFirst->pEList); - } - iBreak = sqlite3VdbeMakeLabel(v); - iCont = sqlite3VdbeMakeLabel(v); - computeLimitRegisters(pParse, p, iBreak); - sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak); VdbeCoverage(v); - r1 = sqlite3GetTempReg(pParse); - iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1); - sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0); VdbeCoverage(v); - sqlite3ReleaseTempReg(pParse, r1); - selectInnerLoop(pParse, p, p->pEList, tab1, - 0, 0, &dest, iCont, iBreak); - sqlite3VdbeResolveLabel(v, iCont); - sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart); VdbeCoverage(v); - sqlite3VdbeResolveLabel(v, iBreak); - sqlite3VdbeAddOp2(v, OP_Close, tab2, 0); - sqlite3VdbeAddOp2(v, OP_Close, tab1, 0); - break; - } - } - - explainComposite(pParse, p->op, iSub1, iSub2, p->op!=TK_ALL); - - /* Compute collating sequences used by - ** temporary tables needed to implement the compound select. - ** Attach the KeyInfo structure to all temporary tables. - ** - ** This section is run by the right-most SELECT statement only. - ** SELECT statements to the left always skip this part. The right-most - ** SELECT might also skip this part if it has no ORDER BY clause and - ** no temp tables are required. - */ - if( p->selFlags & SF_UsesEphemeral ){ - int i; /* Loop counter */ - KeyInfo *pKeyInfo; /* Collating sequence for the result set */ - Select *pLoop; /* For looping through SELECT statements */ - CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */ - int nCol; /* Number of columns in result set */ - - assert( p->pNext==0 ); - nCol = p->pEList->nExpr; - pKeyInfo = sqlite3KeyInfoAlloc(db, nCol, 1); - if( !pKeyInfo ){ - rc = SQLITE_NOMEM; - goto multi_select_end; - } - for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){ - *apColl = multiSelectCollSeq(pParse, p, i); - if( 0==*apColl ){ - *apColl = db->pDfltColl; - } - } - - for(pLoop=p; pLoop; pLoop=pLoop->pPrior){ - for(i=0; i<2; i++){ - int addr = pLoop->addrOpenEphm[i]; - if( addr<0 ){ - /* If [0] is unused then [1] is also unused. So we can - ** always safely abort as soon as the first unused slot is found */ - assert( pLoop->addrOpenEphm[1]<0 ); - break; - } - sqlite3VdbeChangeP2(v, addr, nCol); - sqlite3VdbeChangeP4(v, addr, (char*)sqlite3KeyInfoRef(pKeyInfo), - P4_KEYINFO); - pLoop->addrOpenEphm[i] = -1; - } - } - sqlite3KeyInfoUnref(pKeyInfo); - } - -multi_select_end: - pDest->iSdst = dest.iSdst; - pDest->nSdst = dest.nSdst; - sqlite3SelectDelete(db, pDelete); - return rc; -} -#endif /* SQLITE_OMIT_COMPOUND_SELECT */ - -/* -** Error message for when two or more terms of a compound select have different -** size result sets. -*/ -void sqlite3SelectWrongNumTermsError(Parse *pParse, Select *p){ - if( p->selFlags & SF_Values ){ - sqlite3ErrorMsg(pParse, "all VALUES must have the same number of terms"); - }else{ - sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s" - " do not have the same number of result columns", selectOpName(p->op)); - } -} - -/* -** Code an output subroutine for a coroutine implementation of a -** SELECT statment. -** -** The data to be output is contained in pIn->iSdst. There are -** pIn->nSdst columns to be output. pDest is where the output should -** be sent. -** -** regReturn is the number of the register holding the subroutine -** return address. -** -** If regPrev>0 then it is the first register in a vector that -** records the previous output. mem[regPrev] is a flag that is false -** if there has been no previous output. If regPrev>0 then code is -** generated to suppress duplicates. pKeyInfo is used for comparing -** keys. -** -** If the LIMIT found in p->iLimit is reached, jump immediately to -** iBreak. -*/ -static int generateOutputSubroutine( - Parse *pParse, /* Parsing context */ - Select *p, /* The SELECT statement */ - SelectDest *pIn, /* Coroutine supplying data */ - SelectDest *pDest, /* Where to send the data */ - int regReturn, /* The return address register */ - int regPrev, /* Previous result register. No uniqueness if 0 */ - KeyInfo *pKeyInfo, /* For comparing with previous entry */ - int iBreak /* Jump here if we hit the LIMIT */ -){ - Vdbe *v = pParse->pVdbe; - int iContinue; - int addr; - - addr = sqlite3VdbeCurrentAddr(v); - iContinue = sqlite3VdbeMakeLabel(v); - - /* Suppress duplicates for UNION, EXCEPT, and INTERSECT - */ - if( regPrev ){ - int addr1, addr2; - addr1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev); VdbeCoverage(v); - addr2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iSdst, regPrev+1, pIn->nSdst, - (char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO); - sqlite3VdbeAddOp3(v, OP_Jump, addr2+2, iContinue, addr2+2); VdbeCoverage(v); - sqlite3VdbeJumpHere(v, addr1); - sqlite3VdbeAddOp3(v, OP_Copy, pIn->iSdst, regPrev+1, pIn->nSdst-1); - sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev); - } - if( pParse->db->mallocFailed ) return 0; - - /* Suppress the first OFFSET entries if there is an OFFSET clause - */ - codeOffset(v, p->iOffset, iContinue); - - assert( pDest->eDest!=SRT_Exists ); - assert( pDest->eDest!=SRT_Table ); - switch( pDest->eDest ){ - /* Store the result as data using a unique key. - */ - case SRT_EphemTab: { - int r1 = sqlite3GetTempReg(pParse); - int r2 = sqlite3GetTempReg(pParse); - sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iSdst, pIn->nSdst, r1); - sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iSDParm, r2); - sqlite3VdbeAddOp3(v, OP_Insert, pDest->iSDParm, r1, r2); - sqlite3VdbeChangeP5(v, OPFLAG_APPEND); - sqlite3ReleaseTempReg(pParse, r2); - sqlite3ReleaseTempReg(pParse, r1); - break; - } - -#ifndef SQLITE_OMIT_SUBQUERY - /* If we are creating a set for an "expr IN (SELECT ...)" construct, - ** then there should be a single item on the stack. Write this - ** item into the set table with bogus data. - */ - case SRT_Set: { - int r1; - assert( pIn->nSdst==1 || pParse->nErr>0 ); - pDest->affSdst = - sqlite3CompareAffinity(p->pEList->a[0].pExpr, pDest->affSdst); - r1 = sqlite3GetTempReg(pParse); - sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iSdst, 1, r1, &pDest->affSdst,1); - sqlite3ExprCacheAffinityChange(pParse, pIn->iSdst, 1); - sqlite3VdbeAddOp2(v, OP_IdxInsert, pDest->iSDParm, r1); - sqlite3ReleaseTempReg(pParse, r1); - break; - } - - /* If this is a scalar select that is part of an expression, then - ** store the results in the appropriate memory cell and break out - ** of the scan loop. - */ - case SRT_Mem: { - assert( pIn->nSdst==1 || pParse->nErr>0 ); testcase( pIn->nSdst!=1 ); - sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSDParm, 1); - /* The LIMIT clause will jump out of the loop for us */ - break; - } -#endif /* #ifndef SQLITE_OMIT_SUBQUERY */ - - /* The results are stored in a sequence of registers - ** starting at pDest->iSdst. Then the co-routine yields. - */ - case SRT_Coroutine: { - if( pDest->iSdst==0 ){ - pDest->iSdst = sqlite3GetTempRange(pParse, pIn->nSdst); - pDest->nSdst = pIn->nSdst; - } - sqlite3ExprCodeMove(pParse, pIn->iSdst, pDest->iSdst, pIn->nSdst); - sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm); - break; - } - - /* If none of the above, then the result destination must be - ** SRT_Output. This routine is never called with any other - ** destination other than the ones handled above or SRT_Output. - ** - ** For SRT_Output, results are stored in a sequence of registers. - ** Then the OP_ResultRow opcode is used to cause sqlite3_step() to - ** return the next row of result. - */ - default: { - assert( pDest->eDest==SRT_Output ); - sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iSdst, pIn->nSdst); - sqlite3ExprCacheAffinityChange(pParse, pIn->iSdst, pIn->nSdst); - break; - } - } - - /* Jump to the end of the loop if the LIMIT is reached. - */ - if( p->iLimit ){ - sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v); - } - - /* Generate the subroutine return - */ - sqlite3VdbeResolveLabel(v, iContinue); - sqlite3VdbeAddOp1(v, OP_Return, regReturn); - - return addr; -} - -/* -** Alternative compound select code generator for cases when there -** is an ORDER BY clause. -** -** We assume a query of the following form: -** -** <selectA> <operator> <selectB> ORDER BY <orderbylist> -** -** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea -** is to code both <selectA> and <selectB> with the ORDER BY clause as -** co-routines. Then run the co-routines in parallel and merge the results -** into the output. In addition to the two coroutines (called selectA and -** selectB) there are 7 subroutines: -** -** outA: Move the output of the selectA coroutine into the output -** of the compound query. -** -** outB: Move the output of the selectB coroutine into the output -** of the compound query. (Only generated for UNION and -** UNION ALL. EXCEPT and INSERTSECT never output a row that -** appears only in B.) -** -** AltB: Called when there is data from both coroutines and A<B. -** -** AeqB: Called when there is data from both coroutines and A==B. -** -** AgtB: Called when there is data from both coroutines and A>B. -** -** EofA: Called when data is exhausted from selectA. -** -** EofB: Called when data is exhausted from selectB. -** -** The implementation of the latter five subroutines depend on which -** <operator> is used: -** -** -** UNION ALL UNION EXCEPT INTERSECT -** ------------- ----------------- -------------- ----------------- -** AltB: outA, nextA outA, nextA outA, nextA nextA -** -** AeqB: outA, nextA nextA nextA outA, nextA -** -** AgtB: outB, nextB outB, nextB nextB nextB -** -** EofA: outB, nextB outB, nextB halt halt -** -** EofB: outA, nextA outA, nextA outA, nextA halt -** -** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA -** causes an immediate jump to EofA and an EOF on B following nextB causes -** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or -** following nextX causes a jump to the end of the select processing. -** -** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled -** within the output subroutine. The regPrev register set holds the previously -** output value. A comparison is made against this value and the output -** is skipped if the next results would be the same as the previous. -** -** The implementation plan is to implement the two coroutines and seven -** subroutines first, then put the control logic at the bottom. Like this: -** -** goto Init -** coA: coroutine for left query (A) -** coB: coroutine for right query (B) -** outA: output one row of A -** outB: output one row of B (UNION and UNION ALL only) -** EofA: ... -** EofB: ... -** AltB: ... -** AeqB: ... -** AgtB: ... -** Init: initialize coroutine registers -** yield coA -** if eof(A) goto EofA -** yield coB -** if eof(B) goto EofB -** Cmpr: Compare A, B -** Jump AltB, AeqB, AgtB -** End: ... -** -** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not -** actually called using Gosub and they do not Return. EofA and EofB loop -** until all data is exhausted then jump to the "end" labe. AltB, AeqB, -** and AgtB jump to either L2 or to one of EofA or EofB. -*/ -#ifndef SQLITE_OMIT_COMPOUND_SELECT -static int multiSelectOrderBy( - Parse *pParse, /* Parsing context */ - Select *p, /* The right-most of SELECTs to be coded */ - SelectDest *pDest /* What to do with query results */ -){ - int i, j; /* Loop counters */ - Select *pPrior; /* Another SELECT immediately to our left */ - Vdbe *v; /* Generate code to this VDBE */ - SelectDest destA; /* Destination for coroutine A */ - SelectDest destB; /* Destination for coroutine B */ - int regAddrA; /* Address register for select-A coroutine */ - int regAddrB; /* Address register for select-B coroutine */ - int addrSelectA; /* Address of the select-A coroutine */ - int addrSelectB; /* Address of the select-B coroutine */ - int regOutA; /* Address register for the output-A subroutine */ - int regOutB; /* Address register for the output-B subroutine */ - int addrOutA; /* Address of the output-A subroutine */ - int addrOutB = 0; /* Address of the output-B subroutine */ - int addrEofA; /* Address of the select-A-exhausted subroutine */ - int addrEofA_noB; /* Alternate addrEofA if B is uninitialized */ - int addrEofB; /* Address of the select-B-exhausted subroutine */ - int addrAltB; /* Address of the A<B subroutine */ - int addrAeqB; /* Address of the A==B subroutine */ - int addrAgtB; /* Address of the A>B subroutine */ - int regLimitA; /* Limit register for select-A */ - int regLimitB; /* Limit register for select-A */ - int regPrev; /* A range of registers to hold previous output */ - int savedLimit; /* Saved value of p->iLimit */ - int savedOffset; /* Saved value of p->iOffset */ - int labelCmpr; /* Label for the start of the merge algorithm */ - int labelEnd; /* Label for the end of the overall SELECT stmt */ - int addr1; /* Jump instructions that get retargetted */ - int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */ - KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */ - KeyInfo *pKeyMerge; /* Comparison information for merging rows */ - sqlite3 *db; /* Database connection */ - ExprList *pOrderBy; /* The ORDER BY clause */ - int nOrderBy; /* Number of terms in the ORDER BY clause */ - int *aPermute; /* Mapping from ORDER BY terms to result set columns */ -#ifndef SQLITE_OMIT_EXPLAIN - int iSub1; /* EQP id of left-hand query */ - int iSub2; /* EQP id of right-hand query */ -#endif - - assert( p->pOrderBy!=0 ); - assert( pKeyDup==0 ); /* "Managed" code needs this. Ticket #3382. */ - db = pParse->db; - v = pParse->pVdbe; - assert( v!=0 ); /* Already thrown the error if VDBE alloc failed */ - labelEnd = sqlite3VdbeMakeLabel(v); - labelCmpr = sqlite3VdbeMakeLabel(v); - - - /* Patch up the ORDER BY clause - */ - op = p->op; - pPrior = p->pPrior; - assert( pPrior->pOrderBy==0 ); - pOrderBy = p->pOrderBy; - assert( pOrderBy ); - nOrderBy = pOrderBy->nExpr; - - /* For operators other than UNION ALL we have to make sure that - ** the ORDER BY clause covers every term of the result set. Add - ** terms to the ORDER BY clause as necessary. - */ - if( op!=TK_ALL ){ - for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){ - struct ExprList_item *pItem; - for(j=0, pItem=pOrderBy->a; j<nOrderBy; j++, pItem++){ - assert( pItem->u.x.iOrderByCol>0 ); - if( pItem->u.x.iOrderByCol==i ) break; - } - if( j==nOrderBy ){ - Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0); - if( pNew==0 ) return SQLITE_NOMEM; - pNew->flags |= EP_IntValue; - pNew->u.iValue = i; - pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew); - if( pOrderBy ) pOrderBy->a[nOrderBy++].u.x.iOrderByCol = (u16)i; - } - } - } - - /* Compute the comparison permutation and keyinfo that is used with - ** the permutation used to determine if the next - ** row of results comes from selectA or selectB. Also add explicit - ** collations to the ORDER BY clause terms so that when the subqueries - ** to the right and the left are evaluated, they use the correct - ** collation. - */ - aPermute = sqlite3DbMallocRaw(db, sizeof(int)*nOrderBy); - if( aPermute ){ - struct ExprList_item *pItem; - for(i=0, pItem=pOrderBy->a; i<nOrderBy; i++, pItem++){ - assert( pItem->u.x.iOrderByCol>0 ); - assert( pItem->u.x.iOrderByCol<=p->pEList->nExpr ); - aPermute[i] = pItem->u.x.iOrderByCol - 1; - } - pKeyMerge = multiSelectOrderByKeyInfo(pParse, p, 1); - }else{ - pKeyMerge = 0; - } - - /* Reattach the ORDER BY clause to the query. - */ - p->pOrderBy = pOrderBy; - pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0); - - /* Allocate a range of temporary registers and the KeyInfo needed - ** for the logic that removes duplicate result rows when the - ** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL). - */ - if( op==TK_ALL ){ - regPrev = 0; - }else{ - int nExpr = p->pEList->nExpr; - assert( nOrderBy>=nExpr || db->mallocFailed ); - regPrev = pParse->nMem+1; - pParse->nMem += nExpr+1; - sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev); - pKeyDup = sqlite3KeyInfoAlloc(db, nExpr, 1); - if( pKeyDup ){ - assert( sqlite3KeyInfoIsWriteable(pKeyDup) ); - for(i=0; i<nExpr; i++){ - pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i); - pKeyDup->aSortOrder[i] = 0; - } - } - } - - /* Separate the left and the right query from one another - */ - p->pPrior = 0; - pPrior->pNext = 0; - sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER"); - if( pPrior->pPrior==0 ){ - sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER"); - } - - /* Compute the limit registers */ - computeLimitRegisters(pParse, p, labelEnd); - if( p->iLimit && op==TK_ALL ){ - regLimitA = ++pParse->nMem; - regLimitB = ++pParse->nMem; - sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit, - regLimitA); - sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB); - }else{ - regLimitA = regLimitB = 0; - } - sqlite3ExprDelete(db, p->pLimit); - p->pLimit = 0; - sqlite3ExprDelete(db, p->pOffset); - p->pOffset = 0; - - regAddrA = ++pParse->nMem; - regAddrB = ++pParse->nMem; - regOutA = ++pParse->nMem; - regOutB = ++pParse->nMem; - sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA); - sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB); - - /* Generate a coroutine to evaluate the SELECT statement to the - ** left of the compound operator - the "A" select. - */ - addrSelectA = sqlite3VdbeCurrentAddr(v) + 1; - addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrA, 0, addrSelectA); - VdbeComment((v, "left SELECT")); - pPrior->iLimit = regLimitA; - explainSetInteger(iSub1, pParse->iNextSelectId); - sqlite3Select(pParse, pPrior, &destA); - sqlite3VdbeAddOp1(v, OP_EndCoroutine, regAddrA); - sqlite3VdbeJumpHere(v, addr1); - - /* Generate a coroutine to evaluate the SELECT statement on - ** the right - the "B" select - */ - addrSelectB = sqlite3VdbeCurrentAddr(v) + 1; - addr1 = sqlite3VdbeAddOp3(v, OP_InitCoroutine, regAddrB, 0, addrSelectB); - VdbeComment((v, "right SELECT")); - savedLimit = p->iLimit; - savedOffset = p->iOffset; - p->iLimit = regLimitB; - p->iOffset = 0; - explainSetInteger(iSub2, pParse->iNextSelectId); - sqlite3Select(pParse, p, &destB); - p->iLimit = savedLimit; - p->iOffset = savedOffset; - sqlite3VdbeAddOp1(v, OP_EndCoroutine, regAddrB); - - /* Generate a subroutine that outputs the current row of the A - ** select as the next output row of the compound select. - */ - VdbeNoopComment((v, "Output routine for A")); - addrOutA = generateOutputSubroutine(pParse, - p, &destA, pDest, regOutA, - regPrev, pKeyDup, labelEnd); - - /* Generate a subroutine that outputs the current row of the B - ** select as the next output row of the compound select. - */ - if( op==TK_ALL || op==TK_UNION ){ - VdbeNoopComment((v, "Output routine for B")); - addrOutB = generateOutputSubroutine(pParse, - p, &destB, pDest, regOutB, - regPrev, pKeyDup, labelEnd); - } - sqlite3KeyInfoUnref(pKeyDup); - - /* Generate a subroutine to run when the results from select A - ** are exhausted and only data in select B remains. - */ - if( op==TK_EXCEPT || op==TK_INTERSECT ){ - addrEofA_noB = addrEofA = labelEnd; - }else{ - VdbeNoopComment((v, "eof-A subroutine")); - addrEofA = sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB); - addrEofA_noB = sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, labelEnd); - VdbeCoverage(v); - sqlite3VdbeGoto(v, addrEofA); - p->nSelectRow += pPrior->nSelectRow; - } - - /* Generate a subroutine to run when the results from select B - ** are exhausted and only data in select A remains. - */ - if( op==TK_INTERSECT ){ - addrEofB = addrEofA; - if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow; - }else{ - VdbeNoopComment((v, "eof-B subroutine")); - addrEofB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA); - sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, labelEnd); VdbeCoverage(v); - sqlite3VdbeGoto(v, addrEofB); - } - - /* Generate code to handle the case of A<B - */ - VdbeNoopComment((v, "A-lt-B subroutine")); - addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA); - sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA); VdbeCoverage(v); - sqlite3VdbeGoto(v, labelCmpr); - - /* Generate code to handle the case of A==B - */ - if( op==TK_ALL ){ - addrAeqB = addrAltB; - }else if( op==TK_INTERSECT ){ - addrAeqB = addrAltB; - addrAltB++; - }else{ - VdbeNoopComment((v, "A-eq-B subroutine")); - addrAeqB = - sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA); VdbeCoverage(v); - sqlite3VdbeGoto(v, labelCmpr); - } - - /* Generate code to handle the case of A>B - */ - VdbeNoopComment((v, "A-gt-B subroutine")); - addrAgtB = sqlite3VdbeCurrentAddr(v); - if( op==TK_ALL || op==TK_UNION ){ - sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB); - } - sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v); - sqlite3VdbeGoto(v, labelCmpr); - - /* This code runs once to initialize everything. - */ - sqlite3VdbeJumpHere(v, addr1); - sqlite3VdbeAddOp2(v, OP_Yield, regAddrA, addrEofA_noB); VdbeCoverage(v); - sqlite3VdbeAddOp2(v, OP_Yield, regAddrB, addrEofB); VdbeCoverage(v); - - /* Implement the main merge loop - */ - sqlite3VdbeResolveLabel(v, labelCmpr); - sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY); - sqlite3VdbeAddOp4(v, OP_Compare, destA.iSdst, destB.iSdst, nOrderBy, - (char*)pKeyMerge, P4_KEYINFO); - sqlite3VdbeChangeP5(v, OPFLAG_PERMUTE); - sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB); VdbeCoverage(v); - - /* Jump to the this point in order to terminate the query. - */ - sqlite3VdbeResolveLabel(v, labelEnd); - - /* Set the number of output columns - */ - if( pDest->eDest==SRT_Output ){ - Select *pFirst = pPrior; - while( pFirst->pPrior ) pFirst = pFirst->pPrior; - generateColumnNames(pParse, 0, pFirst->pEList); - } - - /* Reassembly the compound query so that it will be freed correctly - ** by the calling function */ - if( p->pPrior ){ - sqlite3SelectDelete(db, p->pPrior); - } - p->pPrior = pPrior; - pPrior->pNext = p; - - /*** TBD: Insert subroutine calls to close cursors on incomplete - **** subqueries ****/ - explainComposite(pParse, p->op, iSub1, iSub2, 0); - return pParse->nErr!=0; -} -#endif - -#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) -/* Forward Declarations */ -static void substExprList(sqlite3*, ExprList*, int, ExprList*); -static void substSelect(sqlite3*, Select *, int, ExprList*, int); - -/* -** Scan through the expression pExpr. Replace every reference to -** a column in table number iTable with a copy of the iColumn-th -** entry in pEList. (But leave references to the ROWID column -** unchanged.) -** -** This routine is part of the flattening procedure. A subquery -** whose result set is defined by pEList appears as entry in the -** FROM clause of a SELECT such that the VDBE cursor assigned to that -** FORM clause entry is iTable. This routine make the necessary -** changes to pExpr so that it refers directly to the source table -** of the subquery rather the result set of the subquery. -*/ -static Expr *substExpr( - sqlite3 *db, /* Report malloc errors to this connection */ - Expr *pExpr, /* Expr in which substitution occurs */ - int iTable, /* Table to be substituted */ - ExprList *pEList /* Substitute expressions */ -){ - if( pExpr==0 ) return 0; - if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){ - if( pExpr->iColumn<0 ){ - pExpr->op = TK_NULL; - }else{ - Expr *pNew; - assert( pEList!=0 && pExpr->iColumn<pEList->nExpr ); - assert( pExpr->pLeft==0 && pExpr->pRight==0 ); - pNew = sqlite3ExprDup(db, pEList->a[pExpr->iColumn].pExpr, 0); - sqlite3ExprDelete(db, pExpr); - pExpr = pNew; - } - }else{ - pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList); - pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList); - if( ExprHasProperty(pExpr, EP_xIsSelect) ){ - substSelect(db, pExpr->x.pSelect, iTable, pEList, 1); - }else{ - substExprList(db, pExpr->x.pList, iTable, pEList); - } - } - return pExpr; -} -static void substExprList( - sqlite3 *db, /* Report malloc errors here */ - ExprList *pList, /* List to scan and in which to make substitutes */ - int iTable, /* Table to be substituted */ - ExprList *pEList /* Substitute values */ -){ - int i; - if( pList==0 ) return; - for(i=0; i<pList->nExpr; i++){ - pList->a[i].pExpr = substExpr(db, pList->a[i].pExpr, iTable, pEList); - } -} -static void substSelect( - sqlite3 *db, /* Report malloc errors here */ - Select *p, /* SELECT statement in which to make substitutions */ - int iTable, /* Table to be replaced */ - ExprList *pEList, /* Substitute values */ - int doPrior /* Do substitutes on p->pPrior too */ -){ - SrcList *pSrc; - struct SrcList_item *pItem; - int i; - if( !p ) return; - do{ - substExprList(db, p->pEList, iTable, pEList); - substExprList(db, p->pGroupBy, iTable, pEList); - substExprList(db, p->pOrderBy, iTable, pEList); - p->pHaving = substExpr(db, p->pHaving, iTable, pEList); - p->pWhere = substExpr(db, p->pWhere, iTable, pEList); - pSrc = p->pSrc; - assert( pSrc!=0 ); - for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){ - substSelect(db, pItem->pSelect, iTable, pEList, 1); - if( pItem->fg.isTabFunc ){ - substExprList(db, pItem->u1.pFuncArg, iTable, pEList); - } - } - }while( doPrior && (p = p->pPrior)!=0 ); -} -#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ - -#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) -/* -** This routine attempts to flatten subqueries as a performance optimization. -** This routine returns 1 if it makes changes and 0 if no flattening occurs. -** -** To understand the concept of flattening, consider the following -** query: -** -** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5 -** -** The default way of implementing this query is to execute the -** subquery first and store the results in a temporary table, then -** run the outer query on that temporary table. This requires two -** passes over the data. Furthermore, because the temporary table -** has no indices, the WHERE clause on the outer query cannot be -** optimized. -** -** This routine attempts to rewrite queries such as the above into -** a single flat select, like this: -** -** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5 -** -** The code generated for this simplification gives the same result -** but only has to scan the data once. And because indices might -** exist on the table t1, a complete scan of the data might be -** avoided. -** -** Flattening is only attempted if all of the following are true: -** -** (1) The subquery and the outer query do not both use aggregates. -** -** (2) The subquery is not an aggregate or (2a) the outer query is not a join -** and (2b) the outer query does not use subqueries other than the one -** FROM-clause subquery that is a candidate for flattening. (2b is -** due to ticket [2f7170d73bf9abf80] from 2015-02-09.) -** -** (3) The subquery is not the right operand of a left outer join -** (Originally ticket #306. Strengthened by ticket #3300) -** -** (4) The subquery is not DISTINCT. -** -** (**) At one point restrictions (4) and (5) defined a subset of DISTINCT -** sub-queries that were excluded from this optimization. Restriction -** (4) has since been expanded to exclude all DISTINCT subqueries. -** -** (6) The subquery does not use aggregates or the outer query is not -** DISTINCT. -** -** (7) The subquery has a FROM clause. TODO: For subqueries without -** A FROM clause, consider adding a FROM close with the special -** table sqlite_once that consists of a single row containing a -** single NULL. -** -** (8) The subquery does not use LIMIT or the outer query is not a join. -** -** (9) The subquery does not use LIMIT or the outer query does not use -** aggregates. -** -** (**) Restriction (10) was removed from the code on 2005-02-05 but we -** accidently carried the comment forward until 2014-09-15. Original -** text: "The subquery does not use aggregates or the outer query -** does not use LIMIT." -** -** (11) The subquery and the outer query do not both have ORDER BY clauses. -** -** (**) Not implemented. Subsumed into restriction (3). Was previously -** a separate restriction deriving from ticket #350. -** -** (13) The subquery and outer query do not both use LIMIT. -** -** (14) The subquery does not use OFFSET. -** -** (15) The outer query is not part of a compound select or the -** subquery does not have a LIMIT clause. -** (See ticket #2339 and ticket [02a8e81d44]). -** -** (16) The outer query is not an aggregate or the subquery does -** not contain ORDER BY. (Ticket #2942) This used to not matter -** until we introduced the group_concat() function. -** -** (17) The sub-query is not a compound select, or it is a UNION ALL -** compound clause made up entirely of non-aggregate queries, and -** the parent query: -** -** * is not itself part of a compound select, -** * is not an aggregate or DISTINCT query, and -** * is not a join -** -** The parent and sub-query may contain WHERE clauses. Subject to -** rules (11), (13) and (14), they may also contain ORDER BY, -** LIMIT and OFFSET clauses. The subquery cannot use any compound -** operator other than UNION ALL because all the other compound -** operators have an implied DISTINCT which is disallowed by -** restriction (4). -** -** Also, each component of the sub-query must return the same number -** of result columns. This is actually a requirement for any compound -** SELECT statement, but all the code here does is make sure that no -** such (illegal) sub-query is flattened. The caller will detect the -** syntax error and return a detailed message. -** -** (18) If the sub-query is a compound select, then all terms of the -** ORDER by clause of the parent must be simple references to -** columns of the sub-query. -** -** (19) The subquery does not use LIMIT or the outer query does not -** have a WHERE clause. -** -** (20) If the sub-query is a compound select, then it must not use -** an ORDER BY clause. Ticket #3773. We could relax this constraint -** somewhat by saying that the terms of the ORDER BY clause must -** appear as unmodified result columns in the outer query. But we -** have other optimizations in mind to deal with that case. -** -** (21) The subquery does not use LIMIT or the outer query is not -** DISTINCT. (See ticket [752e1646fc]). -** -** (22) The subquery is not a recursive CTE. -** -** (23) The parent is not a recursive CTE, or the sub-query is not a -** compound query. This restriction is because transforming the -** parent to a compound query confuses the code that handles -** recursive queries in multiSelect(). -** -** (24) The subquery is not an aggregate that uses the built-in min() or -** or max() functions. (Without this restriction, a query like: -** "SELECT x FROM (SELECT max(y), x FROM t1)" would not necessarily -** return the value X for which Y was maximal.) -** -** -** In this routine, the "p" parameter is a pointer to the outer query. -** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query -** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates. -** -** If flattening is not attempted, this routine is a no-op and returns 0. -** If flattening is attempted this routine returns 1. -** -** All of the expression analysis must occur on both the outer query and -** the subquery before this routine runs. -*/ -static int flattenSubquery( - Parse *pParse, /* Parsing context */ - Select *p, /* The parent or outer SELECT statement */ - int iFrom, /* Index in p->pSrc->a[] of the inner subquery */ - int isAgg, /* True if outer SELECT uses aggregate functions */ - int subqueryIsAgg /* True if the subquery uses aggregate functions */ -){ - const char *zSavedAuthContext = pParse->zAuthContext; - Select *pParent; /* Current UNION ALL term of the other query */ - Select *pSub; /* The inner query or "subquery" */ - Select *pSub1; /* Pointer to the rightmost select in sub-query */ - SrcList *pSrc; /* The FROM clause of the outer query */ - SrcList *pSubSrc; /* The FROM clause of the subquery */ - ExprList *pList; /* The result set of the outer query */ - int iParent; /* VDBE cursor number of the pSub result set temp table */ - int i; /* Loop counter */ - Expr *pWhere; /* The WHERE clause */ - struct SrcList_item *pSubitem; /* The subquery */ - sqlite3 *db = pParse->db; - - /* Check to see if flattening is permitted. Return 0 if not. - */ - assert( p!=0 ); - assert( p->pPrior==0 ); /* Unable to flatten compound queries */ - if( OptimizationDisabled(db, SQLITE_QueryFlattener) ) return 0; - pSrc = p->pSrc; - assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc ); - pSubitem = &pSrc->a[iFrom]; - iParent = pSubitem->iCursor; - pSub = pSubitem->pSelect; - assert( pSub!=0 ); - if( subqueryIsAgg ){ - if( isAgg ) return 0; /* Restriction (1) */ - if( pSrc->nSrc>1 ) return 0; /* Restriction (2a) */ - if( (p->pWhere && ExprHasProperty(p->pWhere,EP_Subquery)) - || (sqlite3ExprListFlags(p->pEList) & EP_Subquery)!=0 - || (sqlite3ExprListFlags(p->pOrderBy) & EP_Subquery)!=0 - ){ - return 0; /* Restriction (2b) */ - } - } - - pSubSrc = pSub->pSrc; - assert( pSubSrc ); - /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants, - ** not arbitrary expressions, we allowed some combining of LIMIT and OFFSET - ** because they could be computed at compile-time. But when LIMIT and OFFSET - ** became arbitrary expressions, we were forced to add restrictions (13) - ** and (14). */ - if( pSub->pLimit && p->pLimit ) return 0; /* Restriction (13) */ - if( pSub->pOffset ) return 0; /* Restriction (14) */ - if( (p->selFlags & SF_Compound)!=0 && pSub->pLimit ){ - return 0; /* Restriction (15) */ - } - if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */ - if( pSub->selFlags & SF_Distinct ) return 0; /* Restriction (5) */ - if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){ - return 0; /* Restrictions (8)(9) */ - } - if( (p->selFlags & SF_Distinct)!=0 && subqueryIsAgg ){ - return 0; /* Restriction (6) */ - } - if( p->pOrderBy && pSub->pOrderBy ){ - return 0; /* Restriction (11) */ - } - if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */ - if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */ - if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){ - return 0; /* Restriction (21) */ - } - testcase( pSub->selFlags & SF_Recursive ); - testcase( pSub->selFlags & SF_MinMaxAgg ); - if( pSub->selFlags & (SF_Recursive|SF_MinMaxAgg) ){ - return 0; /* Restrictions (22) and (24) */ - } - if( (p->selFlags & SF_Recursive) && pSub->pPrior ){ - return 0; /* Restriction (23) */ - } - - /* OBSOLETE COMMENT 1: - ** Restriction 3: If the subquery is a join, make sure the subquery is - ** not used as the right operand of an outer join. Examples of why this - ** is not allowed: - ** - ** t1 LEFT OUTER JOIN (t2 JOIN t3) - ** - ** If we flatten the above, we would get - ** - ** (t1 LEFT OUTER JOIN t2) JOIN t3 - ** - ** which is not at all the same thing. - ** - ** OBSOLETE COMMENT 2: - ** Restriction 12: If the subquery is the right operand of a left outer - ** join, make sure the subquery has no WHERE clause. - ** An examples of why this is not allowed: - ** - ** t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0) - ** - ** If we flatten the above, we would get - ** - ** (t1 LEFT OUTER JOIN t2) WHERE t2.x>0 - ** - ** But the t2.x>0 test will always fail on a NULL row of t2, which - ** effectively converts the OUTER JOIN into an INNER JOIN. - ** - ** THIS OVERRIDES OBSOLETE COMMENTS 1 AND 2 ABOVE: - ** Ticket #3300 shows that flattening the right term of a LEFT JOIN - ** is fraught with danger. Best to avoid the whole thing. If the - ** subquery is the right term of a LEFT JOIN, then do not flatten. - */ - if( (pSubitem->fg.jointype & JT_OUTER)!=0 ){ - return 0; - } - - /* Restriction 17: If the sub-query is a compound SELECT, then it must - ** use only the UNION ALL operator. And none of the simple select queries - ** that make up the compound SELECT are allowed to be aggregate or distinct - ** queries. - */ - if( pSub->pPrior ){ - if( pSub->pOrderBy ){ - return 0; /* Restriction 20 */ - } - if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){ - return 0; - } - for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){ - testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct ); - testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate ); - assert( pSub->pSrc!=0 ); - assert( pSub->pEList->nExpr==pSub1->pEList->nExpr ); - if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0 - || (pSub1->pPrior && pSub1->op!=TK_ALL) - || pSub1->pSrc->nSrc<1 - ){ - return 0; - } - testcase( pSub1->pSrc->nSrc>1 ); - } - - /* Restriction 18. */ - if( p->pOrderBy ){ - int ii; - for(ii=0; ii<p->pOrderBy->nExpr; ii++){ - if( p->pOrderBy->a[ii].u.x.iOrderByCol==0 ) return 0; - } - } - } - - /***** If we reach this point, flattening is permitted. *****/ - SELECTTRACE(1,pParse,p,("flatten %s.%p from term %d\n", - pSub->zSelName, pSub, iFrom)); - - /* Authorize the subquery */ - pParse->zAuthContext = pSubitem->zName; - TESTONLY(i =) sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0); - testcase( i==SQLITE_DENY ); - pParse->zAuthContext = zSavedAuthContext; - - /* If the sub-query is a compound SELECT statement, then (by restrictions - ** 17 and 18 above) it must be a UNION ALL and the parent query must - ** be of the form: - ** - ** SELECT <expr-list> FROM (<sub-query>) <where-clause> - ** - ** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block - ** creates N-1 copies of the parent query without any ORDER BY, LIMIT or - ** OFFSET clauses and joins them to the left-hand-side of the original - ** using UNION ALL operators. In this case N is the number of simple - ** select statements in the compound sub-query. - ** - ** Example: - ** - ** SELECT a+1 FROM ( - ** SELECT x FROM tab - ** UNION ALL - ** SELECT y FROM tab - ** UNION ALL - ** SELECT abs(z*2) FROM tab2 - ** ) WHERE a!=5 ORDER BY 1 - ** - ** Transformed into: - ** - ** SELECT x+1 FROM tab WHERE x+1!=5 - ** UNION ALL - ** SELECT y+1 FROM tab WHERE y+1!=5 - ** UNION ALL - ** SELECT abs(z*2)+1 FROM tab2 WHERE abs(z*2)+1!=5 - ** ORDER BY 1 - ** - ** We call this the "compound-subquery flattening". - */ - for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){ - Select *pNew; - ExprList *pOrderBy = p->pOrderBy; - Expr *pLimit = p->pLimit; - Expr *pOffset = p->pOffset; - Select *pPrior = p->pPrior; - p->pOrderBy = 0; - p->pSrc = 0; - p->pPrior = 0; - p->pLimit = 0; - p->pOffset = 0; - pNew = sqlite3SelectDup(db, p, 0); - sqlite3SelectSetName(pNew, pSub->zSelName); - p->pOffset = pOffset; - p->pLimit = pLimit; - p->pOrderBy = pOrderBy; - p->pSrc = pSrc; - p->op = TK_ALL; - if( pNew==0 ){ - p->pPrior = pPrior; - }else{ - pNew->pPrior = pPrior; - if( pPrior ) pPrior->pNext = pNew; - pNew->pNext = p; - p->pPrior = pNew; - SELECTTRACE(2,pParse,p, - ("compound-subquery flattener creates %s.%p as peer\n", - pNew->zSelName, pNew)); - } - if( db->mallocFailed ) return 1; - } - - /* Begin flattening the iFrom-th entry of the FROM clause - ** in the outer query. - */ - pSub = pSub1 = pSubitem->pSelect; - - /* Delete the transient table structure associated with the - ** subquery - */ - sqlite3DbFree(db, pSubitem->zDatabase); - sqlite3DbFree(db, pSubitem->zName); - sqlite3DbFree(db, pSubitem->zAlias); - pSubitem->zDatabase = 0; - pSubitem->zName = 0; - pSubitem->zAlias = 0; - pSubitem->pSelect = 0; - - /* Defer deleting the Table object associated with the - ** subquery until code generation is - ** complete, since there may still exist Expr.pTab entries that - ** refer to the subquery even after flattening. Ticket #3346. - ** - ** pSubitem->pTab is always non-NULL by test restrictions and tests above. - */ - if( ALWAYS(pSubitem->pTab!=0) ){ - Table *pTabToDel = pSubitem->pTab; - if( pTabToDel->nRef==1 ){ - Parse *pToplevel = sqlite3ParseToplevel(pParse); - pTabToDel->pNextZombie = pToplevel->pZombieTab; - pToplevel->pZombieTab = pTabToDel; - }else{ - pTabToDel->nRef--; - } - pSubitem->pTab = 0; - } - - /* The following loop runs once for each term in a compound-subquery - ** flattening (as described above). If we are doing a different kind - ** of flattening - a flattening other than a compound-subquery flattening - - ** then this loop only runs once. - ** - ** This loop moves all of the FROM elements of the subquery into the - ** the FROM clause of the outer query. Before doing this, remember - ** the cursor number for the original outer query FROM element in - ** iParent. The iParent cursor will never be used. Subsequent code - ** will scan expressions looking for iParent references and replace - ** those references with expressions that resolve to the subquery FROM - ** elements we are now copying in. - */ - for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){ - int nSubSrc; - u8 jointype = 0; - pSubSrc = pSub->pSrc; /* FROM clause of subquery */ - nSubSrc = pSubSrc->nSrc; /* Number of terms in subquery FROM clause */ - pSrc = pParent->pSrc; /* FROM clause of the outer query */ - - if( pSrc ){ - assert( pParent==p ); /* First time through the loop */ - jointype = pSubitem->fg.jointype; - }else{ - assert( pParent!=p ); /* 2nd and subsequent times through the loop */ - pSrc = pParent->pSrc = sqlite3SrcListAppend(db, 0, 0, 0); - if( pSrc==0 ){ - assert( db->mallocFailed ); - break; - } - } - - /* The subquery uses a single slot of the FROM clause of the outer - ** query. If the subquery has more than one element in its FROM clause, - ** then expand the outer query to make space for it to hold all elements - ** of the subquery. - ** - ** Example: - ** - ** SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB; - ** - ** The outer query has 3 slots in its FROM clause. One slot of the - ** outer query (the middle slot) is used by the subquery. The next - ** block of code will expand the outer query FROM clause to 4 slots. - ** The middle slot is expanded to two slots in order to make space - ** for the two elements in the FROM clause of the subquery. - */ - if( nSubSrc>1 ){ - pParent->pSrc = pSrc = sqlite3SrcListEnlarge(db, pSrc, nSubSrc-1,iFrom+1); - if( db->mallocFailed ){ - break; - } - } - - /* Transfer the FROM clause terms from the subquery into the - ** outer query. - */ - for(i=0; i<nSubSrc; i++){ - sqlite3IdListDelete(db, pSrc->a[i+iFrom].pUsing); - pSrc->a[i+iFrom] = pSubSrc->a[i]; - memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i])); - } - pSrc->a[iFrom].fg.jointype = jointype; - - /* Now begin substituting subquery result set expressions for - ** references to the iParent in the outer query. - ** - ** Example: - ** - ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b; - ** \ \_____________ subquery __________/ / - ** \_____________________ outer query ______________________________/ - ** - ** We look at every expression in the outer query and every place we see - ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10". - */ - pList = pParent->pEList; - for(i=0; i<pList->nExpr; i++){ - if( pList->a[i].zName==0 ){ - char *zName = sqlite3DbStrDup(db, pList->a[i].zSpan); - sqlite3Dequote(zName); - pList->a[i].zName = zName; - } - } - if( pSub->pOrderBy ){ - /* At this point, any non-zero iOrderByCol values indicate that the - ** ORDER BY column expression is identical to the iOrderByCol'th - ** expression returned by SELECT statement pSub. Since these values - ** do not necessarily correspond to columns in SELECT statement pParent, - ** zero them before transfering the ORDER BY clause. - ** - ** Not doing this may cause an error if a subsequent call to this - ** function attempts to flatten a compound sub-query into pParent - ** (the only way this can happen is if the compound sub-query is - ** currently part of pSub->pSrc). See ticket [d11a6e908f]. */ - ExprList *pOrderBy = pSub->pOrderBy; - for(i=0; i<pOrderBy->nExpr; i++){ - pOrderBy->a[i].u.x.iOrderByCol = 0; - } - assert( pParent->pOrderBy==0 ); - assert( pSub->pPrior==0 ); - pParent->pOrderBy = pOrderBy; - pSub->pOrderBy = 0; - } - pWhere = sqlite3ExprDup(db, pSub->pWhere, 0); - if( subqueryIsAgg ){ - assert( pParent->pHaving==0 ); - pParent->pHaving = pParent->pWhere; - pParent->pWhere = pWhere; - pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving, - sqlite3ExprDup(db, pSub->pHaving, 0)); - assert( pParent->pGroupBy==0 ); - pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0); - }else{ - pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere); - } - substSelect(db, pParent, iParent, pSub->pEList, 0); - - /* The flattened query is distinct if either the inner or the - ** outer query is distinct. - */ - pParent->selFlags |= pSub->selFlags & SF_Distinct; - - /* - ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y; - ** - ** One is tempted to try to add a and b to combine the limits. But this - ** does not work if either limit is negative. - */ - if( pSub->pLimit ){ - pParent->pLimit = pSub->pLimit; - pSub->pLimit = 0; - } - } - - /* Finially, delete what is left of the subquery and return - ** success. - */ - sqlite3SelectDelete(db, pSub1); - -#if SELECTTRACE_ENABLED - if( sqlite3SelectTrace & 0x100 ){ - SELECTTRACE(0x100,pParse,p,("After flattening:\n")); - sqlite3TreeViewSelect(0, p, 0); - } -#endif - - return 1; -} -#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ - - - -#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) -/* -** Make copies of relevant WHERE clause terms of the outer query into -** the WHERE clause of subquery. Example: -** -** SELECT * FROM (SELECT a AS x, c-d AS y FROM t1) WHERE x=5 AND y=10; -** -** Transformed into: -** -** SELECT * FROM (SELECT a AS x, c-d AS y FROM t1 WHERE a=5 AND c-d=10) -** WHERE x=5 AND y=10; -** -** The hope is that the terms added to the inner query will make it more -** efficient. -** -** Do not attempt this optimization if: -** -** (1) The inner query is an aggregate. (In that case, we'd really want -** to copy the outer WHERE-clause terms onto the HAVING clause of the -** inner query. But they probably won't help there so do not bother.) -** -** (2) The inner query is the recursive part of a common table expression. -** -** (3) The inner query has a LIMIT clause (since the changes to the WHERE -** close would change the meaning of the LIMIT). -** -** (4) The inner query is the right operand of a LEFT JOIN. (The caller -** enforces this restriction since this routine does not have enough -** information to know.) -** -** (5) The WHERE clause expression originates in the ON or USING clause -** of a LEFT JOIN. -** -** Return 0 if no changes are made and non-zero if one or more WHERE clause -** terms are duplicated into the subquery. -*/ -static int pushDownWhereTerms( - sqlite3 *db, /* The database connection (for malloc()) */ - Select *pSubq, /* The subquery whose WHERE clause is to be augmented */ - Expr *pWhere, /* The WHERE clause of the outer query */ - int iCursor /* Cursor number of the subquery */ -){ - Expr *pNew; - int nChng = 0; - if( pWhere==0 ) return 0; - if( (pSubq->selFlags & (SF_Aggregate|SF_Recursive))!=0 ){ - return 0; /* restrictions (1) and (2) */ - } - if( pSubq->pLimit!=0 ){ - return 0; /* restriction (3) */ - } - while( pWhere->op==TK_AND ){ - nChng += pushDownWhereTerms(db, pSubq, pWhere->pRight, iCursor); - pWhere = pWhere->pLeft; - } - if( ExprHasProperty(pWhere,EP_FromJoin) ) return 0; /* restriction 5 */ - if( sqlite3ExprIsTableConstant(pWhere, iCursor) ){ - nChng++; - while( pSubq ){ - pNew = sqlite3ExprDup(db, pWhere, 0); - pNew = substExpr(db, pNew, iCursor, pSubq->pEList); - pSubq->pWhere = sqlite3ExprAnd(db, pSubq->pWhere, pNew); - pSubq = pSubq->pPrior; - } - } - return nChng; -} -#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */ - -/* -** Based on the contents of the AggInfo structure indicated by the first -** argument, this function checks if the following are true: -** -** * the query contains just a single aggregate function, -** * the aggregate function is either min() or max(), and -** * the argument to the aggregate function is a column value. -** -** If all of the above are true, then WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX -** is returned as appropriate. Also, *ppMinMax is set to point to the -** list of arguments passed to the aggregate before returning. -** -** Or, if the conditions above are not met, *ppMinMax is set to 0 and -** WHERE_ORDERBY_NORMAL is returned. -*/ -static u8 minMaxQuery(AggInfo *pAggInfo, ExprList **ppMinMax){ - int eRet = WHERE_ORDERBY_NORMAL; /* Return value */ - - *ppMinMax = 0; - if( pAggInfo->nFunc==1 ){ - Expr *pExpr = pAggInfo->aFunc[0].pExpr; /* Aggregate function */ - ExprList *pEList = pExpr->x.pList; /* Arguments to agg function */ - - assert( pExpr->op==TK_AGG_FUNCTION ); - if( pEList && pEList->nExpr==1 && pEList->a[0].pExpr->op==TK_AGG_COLUMN ){ - const char *zFunc = pExpr->u.zToken; - if( sqlite3StrICmp(zFunc, "min")==0 ){ - eRet = WHERE_ORDERBY_MIN; - *ppMinMax = pEList; - }else if( sqlite3StrICmp(zFunc, "max")==0 ){ - eRet = WHERE_ORDERBY_MAX; - *ppMinMax = pEList; - } - } - } - - assert( *ppMinMax==0 || (*ppMinMax)->nExpr==1 ); - return eRet; -} - -/* -** The select statement passed as the first argument is an aggregate query. -** The second argument is the associated aggregate-info object. This -** function tests if the SELECT is of the form: -** -** SELECT count(*) FROM <tbl> -** -** where table is a database table, not a sub-select or view. If the query -** does match this pattern, then a pointer to the Table object representing -** <tbl> is returned. Otherwise, 0 is returned. -*/ -static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){ - Table *pTab; - Expr *pExpr; - - assert( !p->pGroupBy ); - - if( p->pWhere || p->pEList->nExpr!=1 - || p->pSrc->nSrc!=1 || p->pSrc->a[0].pSelect - ){ - return 0; - } - pTab = p->pSrc->a[0].pTab; - pExpr = p->pEList->a[0].pExpr; - assert( pTab && !pTab->pSelect && pExpr ); - - if( IsVirtual(pTab) ) return 0; - if( pExpr->op!=TK_AGG_FUNCTION ) return 0; - if( NEVER(pAggInfo->nFunc==0) ) return 0; - if( (pAggInfo->aFunc[0].pFunc->funcFlags&SQLITE_FUNC_COUNT)==0 ) return 0; - if( pExpr->flags&EP_Distinct ) return 0; - - return pTab; -} - -/* -** If the source-list item passed as an argument was augmented with an -** INDEXED BY clause, then try to locate the specified index. If there -** was such a clause and the named index cannot be found, return -** SQLITE_ERROR and leave an error in pParse. Otherwise, populate -** pFrom->pIndex and return SQLITE_OK. -*/ -int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){ - if( pFrom->pTab && pFrom->fg.isIndexedBy ){ - Table *pTab = pFrom->pTab; - char *zIndexedBy = pFrom->u1.zIndexedBy; - Index *pIdx; - for(pIdx=pTab->pIndex; - pIdx && sqlite3StrICmp(pIdx->zName, zIndexedBy); - pIdx=pIdx->pNext - ); - if( !pIdx ){ - sqlite3ErrorMsg(pParse, "no such index: %s", zIndexedBy, 0); - pParse->checkSchema = 1; - return SQLITE_ERROR; - } - pFrom->pIBIndex = pIdx; - } - return SQLITE_OK; -} -/* -** Detect compound SELECT statements that use an ORDER BY clause with -** an alternative collating sequence. -** -** SELECT ... FROM t1 EXCEPT SELECT ... FROM t2 ORDER BY .. COLLATE ... -** -** These are rewritten as a subquery: -** -** SELECT * FROM (SELECT ... FROM t1 EXCEPT SELECT ... FROM t2) -** ORDER BY ... COLLATE ... -** -** This transformation is necessary because the multiSelectOrderBy() routine -** above that generates the code for a compound SELECT with an ORDER BY clause -** uses a merge algorithm that requires the same collating sequence on the -** result columns as on the ORDER BY clause. See ticket -** http://www.sqlite.org/src/info/6709574d2a -** -** This transformation is only needed for EXCEPT, INTERSECT, and UNION. -** The UNION ALL operator works fine with multiSelectOrderBy() even when -** there are COLLATE terms in the ORDER BY. -*/ -static int convertCompoundSelectToSubquery(Walker *pWalker, Select *p){ - int i; - Select *pNew; - Select *pX; - sqlite3 *db; - struct ExprList_item *a; - SrcList *pNewSrc; - Parse *pParse; - Token dummy; - - if( p->pPrior==0 ) return WRC_Continue; - if( p->pOrderBy==0 ) return WRC_Continue; - for(pX=p; pX && (pX->op==TK_ALL || pX->op==TK_SELECT); pX=pX->pPrior){} - if( pX==0 ) return WRC_Continue; - a = p->pOrderBy->a; - for(i=p->pOrderBy->nExpr-1; i>=0; i--){ - if( a[i].pExpr->flags & EP_Collate ) break; - } - if( i<0 ) return WRC_Continue; - - /* If we reach this point, that means the transformation is required. */ - - pParse = pWalker->pParse; - db = pParse->db; - pNew = sqlite3DbMallocZero(db, sizeof(*pNew) ); - if( pNew==0 ) return WRC_Abort; - memset(&dummy, 0, sizeof(dummy)); - pNewSrc = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&dummy,pNew,0,0); - if( pNewSrc==0 ) return WRC_Abort; - *pNew = *p; - p->pSrc = pNewSrc; - p->pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ALL, 0)); - p->op = TK_SELECT; - p->pWhere = 0; - pNew->pGroupBy = 0; - pNew->pHaving = 0; - pNew->pOrderBy = 0; - p->pPrior = 0; - p->pNext = 0; - p->pWith = 0; - p->selFlags &= ~SF_Compound; - assert( (p->selFlags & SF_Converted)==0 ); - p->selFlags |= SF_Converted; - assert( pNew->pPrior!=0 ); - pNew->pPrior->pNext = pNew; - pNew->pLimit = 0; - pNew->pOffset = 0; - return WRC_Continue; -} - -#ifndef SQLITE_OMIT_CTE -/* -** Argument pWith (which may be NULL) points to a linked list of nested -** WITH contexts, from inner to outermost. If the table identified by -** FROM clause element pItem is really a common-table-expression (CTE) -** then return a pointer to the CTE definition for that table. Otherwise -** return NULL. -** -** If a non-NULL value is returned, set *ppContext to point to the With -** object that the returned CTE belongs to. -*/ -static struct Cte *searchWith( - With *pWith, /* Current outermost WITH clause */ - struct SrcList_item *pItem, /* FROM clause element to resolve */ - With **ppContext /* OUT: WITH clause return value belongs to */ -){ - const char *zName; - if( pItem->zDatabase==0 && (zName = pItem->zName)!=0 ){ - With *p; - for(p=pWith; p; p=p->pOuter){ - int i; - for(i=0; i<p->nCte; i++){ - if( sqlite3StrICmp(zName, p->a[i].zName)==0 ){ - *ppContext = p; - return &p->a[i]; - } - } - } - } - return 0; -} - -/* The code generator maintains a stack of active WITH clauses -** with the inner-most WITH clause being at the top of the stack. -** -** This routine pushes the WITH clause passed as the second argument -** onto the top of the stack. If argument bFree is true, then this -** WITH clause will never be popped from the stack. In this case it -** should be freed along with the Parse object. In other cases, when -** bFree==0, the With object will be freed along with the SELECT -** statement with which it is associated. -*/ -void sqlite3WithPush(Parse *pParse, With *pWith, u8 bFree){ - assert( bFree==0 || pParse->pWith==0 ); - if( pWith ){ - pWith->pOuter = pParse->pWith; - pParse->pWith = pWith; - pParse->bFreeWith = bFree; - } -} - -/* -** This function checks if argument pFrom refers to a CTE declared by -** a WITH clause on the stack currently maintained by the parser. And, -** if currently processing a CTE expression, if it is a recursive -** reference to the current CTE. -** -** If pFrom falls into either of the two categories above, pFrom->pTab -** and other fields are populated accordingly. The caller should check -** (pFrom->pTab!=0) to determine whether or not a successful match -** was found. -** -** Whether or not a match is found, SQLITE_OK is returned if no error -** occurs. If an error does occur, an error message is stored in the -** parser and some error code other than SQLITE_OK returned. -*/ -static int withExpand( - Walker *pWalker, - struct SrcList_item *pFrom -){ - Parse *pParse = pWalker->pParse; - sqlite3 *db = pParse->db; - struct Cte *pCte; /* Matched CTE (or NULL if no match) */ - With *pWith; /* WITH clause that pCte belongs to */ - - assert( pFrom->pTab==0 ); - - pCte = searchWith(pParse->pWith, pFrom, &pWith); - if( pCte ){ - Table *pTab; - ExprList *pEList; - Select *pSel; - Select *pLeft; /* Left-most SELECT statement */ - int bMayRecursive; /* True if compound joined by UNION [ALL] */ - With *pSavedWith; /* Initial value of pParse->pWith */ - - /* If pCte->zCteErr is non-NULL at this point, then this is an illegal - ** recursive reference to CTE pCte. Leave an error in pParse and return - ** early. If pCte->zCteErr is NULL, then this is not a recursive reference. - ** In this case, proceed. */ - if( pCte->zCteErr ){ - sqlite3ErrorMsg(pParse, pCte->zCteErr, pCte->zName); - return SQLITE_ERROR; - } - - assert( pFrom->pTab==0 ); - pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table)); - if( pTab==0 ) return WRC_Abort; - pTab->nRef = 1; - pTab->zName = sqlite3DbStrDup(db, pCte->zName); - pTab->iPKey = -1; - pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) ); - pTab->tabFlags |= TF_Ephemeral | TF_NoVisibleRowid; - pFrom->pSelect = sqlite3SelectDup(db, pCte->pSelect, 0); - if( db->mallocFailed ) return SQLITE_NOMEM; - assert( pFrom->pSelect ); - - /* Check if this is a recursive CTE. */ - pSel = pFrom->pSelect; - bMayRecursive = ( pSel->op==TK_ALL || pSel->op==TK_UNION ); - if( bMayRecursive ){ - int i; - SrcList *pSrc = pFrom->pSelect->pSrc; - for(i=0; i<pSrc->nSrc; i++){ - struct SrcList_item *pItem = &pSrc->a[i]; - if( pItem->zDatabase==0 - && pItem->zName!=0 - && 0==sqlite3StrICmp(pItem->zName, pCte->zName) - ){ - pItem->pTab = pTab; - pItem->fg.isRecursive = 1; - pTab->nRef++; - pSel->selFlags |= SF_Recursive; - } - } - } - - /* Only one recursive reference is permitted. */ - if( pTab->nRef>2 ){ - sqlite3ErrorMsg( - pParse, "multiple references to recursive table: %s", pCte->zName - ); - return SQLITE_ERROR; - } - assert( pTab->nRef==1 || ((pSel->selFlags&SF_Recursive) && pTab->nRef==2 )); - - pCte->zCteErr = "circular reference: %s"; - pSavedWith = pParse->pWith; - pParse->pWith = pWith; - sqlite3WalkSelect(pWalker, bMayRecursive ? pSel->pPrior : pSel); - - for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior); - pEList = pLeft->pEList; - if( pCte->pCols ){ - if( pEList && pEList->nExpr!=pCte->pCols->nExpr ){ - sqlite3ErrorMsg(pParse, "table %s has %d values for %d columns", - pCte->zName, pEList->nExpr, pCte->pCols->nExpr - ); - pParse->pWith = pSavedWith; - return SQLITE_ERROR; - } - pEList = pCte->pCols; - } - - sqlite3ColumnsFromExprList(pParse, pEList, &pTab->nCol, &pTab->aCol); - if( bMayRecursive ){ - if( pSel->selFlags & SF_Recursive ){ - pCte->zCteErr = "multiple recursive references: %s"; - }else{ - pCte->zCteErr = "recursive reference in a subquery: %s"; - } - sqlite3WalkSelect(pWalker, pSel); - } - pCte->zCteErr = 0; - pParse->pWith = pSavedWith; - } - - return SQLITE_OK; -} -#endif - -#ifndef SQLITE_OMIT_CTE -/* -** If the SELECT passed as the second argument has an associated WITH -** clause, pop it from the stack stored as part of the Parse object. -** -** This function is used as the xSelectCallback2() callback by -** sqlite3SelectExpand() when walking a SELECT tree to resolve table -** names and other FROM clause elements. -*/ -static void selectPopWith(Walker *pWalker, Select *p){ - Parse *pParse = pWalker->pParse; - With *pWith = findRightmost(p)->pWith; - if( pWith!=0 ){ - assert( pParse->pWith==pWith ); - pParse->pWith = pWith->pOuter; - } -} -#else -#define selectPopWith 0 -#endif - -/* -** This routine is a Walker callback for "expanding" a SELECT statement. -** "Expanding" means to do the following: -** -** (1) Make sure VDBE cursor numbers have been assigned to every -** element of the FROM clause. -** -** (2) Fill in the pTabList->a[].pTab fields in the SrcList that -** defines FROM clause. When views appear in the FROM clause, -** fill pTabList->a[].pSelect with a copy of the SELECT statement -** that implements the view. A copy is made of the view's SELECT -** statement so that we can freely modify or delete that statement -** without worrying about messing up the persistent representation -** of the view. -** -** (3) Add terms to the WHERE clause to accommodate the NATURAL keyword -** on joins and the ON and USING clause of joins. -** -** (4) Scan the list of columns in the result set (pEList) looking -** for instances of the "*" operator or the TABLE.* operator. -** If found, expand each "*" to be every column in every table -** and TABLE.* to be every column in TABLE. -** -*/ -static int selectExpander(Walker *pWalker, Select *p){ - Parse *pParse = pWalker->pParse; - int i, j, k; - SrcList *pTabList; - ExprList *pEList; - struct SrcList_item *pFrom; - sqlite3 *db = pParse->db; - Expr *pE, *pRight, *pExpr; - u16 selFlags = p->selFlags; - - p->selFlags |= SF_Expanded; - if( db->mallocFailed ){ - return WRC_Abort; - } - if( NEVER(p->pSrc==0) || (selFlags & SF_Expanded)!=0 ){ - return WRC_Prune; - } - pTabList = p->pSrc; - pEList = p->pEList; - if( pWalker->xSelectCallback2==selectPopWith ){ - sqlite3WithPush(pParse, findRightmost(p)->pWith, 0); - } - - /* Make sure cursor numbers have been assigned to all entries in - ** the FROM clause of the SELECT statement. - */ - sqlite3SrcListAssignCursors(pParse, pTabList); - - /* Look up every table named in the FROM clause of the select. If - ** an entry of the FROM clause is a subquery instead of a table or view, - ** then create a transient table structure to describe the subquery. - */ - for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){ - Table *pTab; - assert( pFrom->fg.isRecursive==0 || pFrom->pTab!=0 ); - if( pFrom->fg.isRecursive ) continue; - assert( pFrom->pTab==0 ); -#ifndef SQLITE_OMIT_CTE - if( withExpand(pWalker, pFrom) ) return WRC_Abort; - if( pFrom->pTab ) {} else -#endif - if( pFrom->zName==0 ){ -#ifndef SQLITE_OMIT_SUBQUERY - Select *pSel = pFrom->pSelect; - /* A sub-query in the FROM clause of a SELECT */ - assert( pSel!=0 ); - assert( pFrom->pTab==0 ); - if( sqlite3WalkSelect(pWalker, pSel) ) return WRC_Abort; - pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table)); - if( pTab==0 ) return WRC_Abort; - pTab->nRef = 1; - pTab->zName = sqlite3MPrintf(db, "sqlite_sq_%p", (void*)pTab); - while( pSel->pPrior ){ pSel = pSel->pPrior; } - sqlite3ColumnsFromExprList(pParse, pSel->pEList,&pTab->nCol,&pTab->aCol); - pTab->iPKey = -1; - pTab->nRowLogEst = 200; assert( 200==sqlite3LogEst(1048576) ); - pTab->tabFlags |= TF_Ephemeral; -#endif - }else{ - /* An ordinary table or view name in the FROM clause */ - assert( pFrom->pTab==0 ); - pFrom->pTab = pTab = sqlite3LocateTableItem(pParse, 0, pFrom); - if( pTab==0 ) return WRC_Abort; - if( pTab->nRef==0xffff ){ - sqlite3ErrorMsg(pParse, "too many references to \"%s\": max 65535", - pTab->zName); - pFrom->pTab = 0; - return WRC_Abort; - } - pTab->nRef++; -#if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE) - if( pTab->pSelect || IsVirtual(pTab) ){ - i16 nCol; - if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort; - assert( pFrom->pSelect==0 ); - if( pFrom->fg.isTabFunc && !IsVirtual(pTab) ){ - sqlite3ErrorMsg(pParse, "'%s' is not a function", pTab->zName); - return WRC_Abort; - } - pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect, 0); - sqlite3SelectSetName(pFrom->pSelect, pTab->zName); - nCol = pTab->nCol; - pTab->nCol = -1; - sqlite3WalkSelect(pWalker, pFrom->pSelect); - pTab->nCol = nCol; - } -#endif - } - - /* Locate the index named by the INDEXED BY clause, if any. */ - if( sqlite3IndexedByLookup(pParse, pFrom) ){ - return WRC_Abort; - } - } - - /* Process NATURAL keywords, and ON and USING clauses of joins. - */ - if( db->mallocFailed || sqliteProcessJoin(pParse, p) ){ - return WRC_Abort; - } - - /* For every "*" that occurs in the column list, insert the names of - ** all columns in all tables. And for every TABLE.* insert the names - ** of all columns in TABLE. The parser inserted a special expression - ** with the TK_ALL operator for each "*" that it found in the column list. - ** The following code just has to locate the TK_ALL expressions and expand - ** each one to the list of all columns in all tables. - ** - ** The first loop just checks to see if there are any "*" operators - ** that need expanding. - */ - for(k=0; k<pEList->nExpr; k++){ - pE = pEList->a[k].pExpr; - if( pE->op==TK_ALL ) break; - assert( pE->op!=TK_DOT || pE->pRight!=0 ); - assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) ); - if( pE->op==TK_DOT && pE->pRight->op==TK_ALL ) break; - } - if( k<pEList->nExpr ){ - /* - ** If we get here it means the result set contains one or more "*" - ** operators that need to be expanded. Loop through each expression - ** in the result set and expand them one by one. - */ - struct ExprList_item *a = pEList->a; - ExprList *pNew = 0; - int flags = pParse->db->flags; - int longNames = (flags & SQLITE_FullColNames)!=0 - && (flags & SQLITE_ShortColNames)==0; - - for(k=0; k<pEList->nExpr; k++){ - pE = a[k].pExpr; - pRight = pE->pRight; - assert( pE->op!=TK_DOT || pRight!=0 ); - if( pE->op!=TK_ALL && (pE->op!=TK_DOT || pRight->op!=TK_ALL) ){ - /* This particular expression does not need to be expanded. - */ - pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr); - if( pNew ){ - pNew->a[pNew->nExpr-1].zName = a[k].zName; - pNew->a[pNew->nExpr-1].zSpan = a[k].zSpan; - a[k].zName = 0; - a[k].zSpan = 0; - } - a[k].pExpr = 0; - }else{ - /* This expression is a "*" or a "TABLE.*" and needs to be - ** expanded. */ - int tableSeen = 0; /* Set to 1 when TABLE matches */ - char *zTName = 0; /* text of name of TABLE */ - if( pE->op==TK_DOT ){ - assert( pE->pLeft!=0 ); - assert( !ExprHasProperty(pE->pLeft, EP_IntValue) ); - zTName = pE->pLeft->u.zToken; - } - for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){ - Table *pTab = pFrom->pTab; - Select *pSub = pFrom->pSelect; - char *zTabName = pFrom->zAlias; - const char *zSchemaName = 0; - int iDb; - if( zTabName==0 ){ - zTabName = pTab->zName; - } - if( db->mallocFailed ) break; - if( pSub==0 || (pSub->selFlags & SF_NestedFrom)==0 ){ - pSub = 0; - if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){ - continue; - } - iDb = sqlite3SchemaToIndex(db, pTab->pSchema); - zSchemaName = iDb>=0 ? db->aDb[iDb].zName : "*"; - } - for(j=0; j<pTab->nCol; j++){ - char *zName = pTab->aCol[j].zName; - char *zColname; /* The computed column name */ - char *zToFree; /* Malloced string that needs to be freed */ - Token sColname; /* Computed column name as a token */ - - assert( zName ); - if( zTName && pSub - && sqlite3MatchSpanName(pSub->pEList->a[j].zSpan, 0, zTName, 0)==0 - ){ - continue; - } - - /* If a column is marked as 'hidden' (currently only possible - ** for virtual tables), do not include it in the expanded - ** result-set list. - */ - if( IsHiddenColumn(&pTab->aCol[j]) ){ - assert(IsVirtual(pTab)); - continue; - } - tableSeen = 1; - - if( i>0 && zTName==0 ){ - if( (pFrom->fg.jointype & JT_NATURAL)!=0 - && tableAndColumnIndex(pTabList, i, zName, 0, 0) - ){ - /* In a NATURAL join, omit the join columns from the - ** table to the right of the join */ - continue; - } - if( sqlite3IdListIndex(pFrom->pUsing, zName)>=0 ){ - /* In a join with a USING clause, omit columns in the - ** using clause from the table on the right. */ - continue; - } - } - pRight = sqlite3Expr(db, TK_ID, zName); - zColname = zName; - zToFree = 0; - if( longNames || pTabList->nSrc>1 ){ - Expr *pLeft; - pLeft = sqlite3Expr(db, TK_ID, zTabName); - pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0); - if( zSchemaName ){ - pLeft = sqlite3Expr(db, TK_ID, zSchemaName); - pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pExpr, 0); - } - if( longNames ){ - zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName); - zToFree = zColname; - } - }else{ - pExpr = pRight; - } - pNew = sqlite3ExprListAppend(pParse, pNew, pExpr); - sColname.z = zColname; - sColname.n = sqlite3Strlen30(zColname); - sqlite3ExprListSetName(pParse, pNew, &sColname, 0); - if( pNew && (p->selFlags & SF_NestedFrom)!=0 ){ - struct ExprList_item *pX = &pNew->a[pNew->nExpr-1]; - if( pSub ){ - pX->zSpan = sqlite3DbStrDup(db, pSub->pEList->a[j].zSpan); - testcase( pX->zSpan==0 ); - }else{ - pX->zSpan = sqlite3MPrintf(db, "%s.%s.%s", - zSchemaName, zTabName, zColname); - testcase( pX->zSpan==0 ); - } - pX->bSpanIsTab = 1; - } - sqlite3DbFree(db, zToFree); - } - } - if( !tableSeen ){ - if( zTName ){ - sqlite3ErrorMsg(pParse, "no such table: %s", zTName); - }else{ - sqlite3ErrorMsg(pParse, "no tables specified"); - } - } - } - } - sqlite3ExprListDelete(db, pEList); - p->pEList = pNew; - } -#if SQLITE_MAX_COLUMN - if( p->pEList && p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){ - sqlite3ErrorMsg(pParse, "too many columns in result set"); - } -#endif - return WRC_Continue; -} - -/* -** No-op routine for the parse-tree walker. -** -** When this routine is the Walker.xExprCallback then expression trees -** are walked without any actions being taken at each node. Presumably, -** when this routine is used for Walker.xExprCallback then -** Walker.xSelectCallback is set to do something useful for every -** subquery in the parser tree. -*/ -static int exprWalkNoop(Walker *NotUsed, Expr *NotUsed2){ - UNUSED_PARAMETER2(NotUsed, NotUsed2); - return WRC_Continue; -} - -/* -** This routine "expands" a SELECT statement and all of its subqueries. -** For additional information on what it means to "expand" a SELECT -** statement, see the comment on the selectExpand worker callback above. -** -** Expanding a SELECT statement is the first step in processing a -** SELECT statement. The SELECT statement must be expanded before -** name resolution is performed. -** -** If anything goes wrong, an error message is written into pParse. -** The calling function can detect the problem by looking at pParse->nErr -** and/or pParse->db->mallocFailed. -*/ -static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){ - Walker w; - memset(&w, 0, sizeof(w)); - w.xExprCallback = exprWalkNoop; - w.pParse = pParse; - if( pParse->hasCompound ){ - w.xSelectCallback = convertCompoundSelectToSubquery; - sqlite3WalkSelect(&w, pSelect); - } - w.xSelectCallback = selectExpander; - if( (pSelect->selFlags & SF_MultiValue)==0 ){ - w.xSelectCallback2 = selectPopWith; - } - sqlite3WalkSelect(&w, pSelect); -} - - -#ifndef SQLITE_OMIT_SUBQUERY -/* -** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo() -** interface. -** -** For each FROM-clause subquery, add Column.zType and Column.zColl -** information to the Table structure that represents the result set -** of that subquery. -** -** The Table structure that represents the result set was constructed -** by selectExpander() but the type and collation information was omitted -** at that point because identifiers had not yet been resolved. This -** routine is called after identifier resolution. -*/ -static void selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){ - Parse *pParse; - int i; - SrcList *pTabList; - struct SrcList_item *pFrom; - - assert( p->selFlags & SF_Resolved ); - assert( (p->selFlags & SF_HasTypeInfo)==0 ); - p->selFlags |= SF_HasTypeInfo; - pParse = pWalker->pParse; - pTabList = p->pSrc; - for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){ - Table *pTab = pFrom->pTab; - assert( pTab!=0 ); - if( (pTab->tabFlags & TF_Ephemeral)!=0 ){ - /* A sub-query in the FROM clause of a SELECT */ - Select *pSel = pFrom->pSelect; - if( pSel ){ - while( pSel->pPrior ) pSel = pSel->pPrior; - selectAddColumnTypeAndCollation(pParse, pTab, pSel); - } - } - } -} -#endif - - -/* -** This routine adds datatype and collating sequence information to -** the Table structures of all FROM-clause subqueries in a -** SELECT statement. -** -** Use this routine after name resolution. -*/ -static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){ -#ifndef SQLITE_OMIT_SUBQUERY - Walker w; - memset(&w, 0, sizeof(w)); - w.xSelectCallback2 = selectAddSubqueryTypeInfo; - w.xExprCallback = exprWalkNoop; - w.pParse = pParse; - sqlite3WalkSelect(&w, pSelect); -#endif -} - - -/* -** This routine sets up a SELECT statement for processing. The -** following is accomplished: -** -** * VDBE Cursor numbers are assigned to all FROM-clause terms. -** * Ephemeral Table objects are created for all FROM-clause subqueries. -** * ON and USING clauses are shifted into WHERE statements -** * Wildcards "*" and "TABLE.*" in result sets are expanded. -** * Identifiers in expression are matched to tables. -** -** This routine acts recursively on all subqueries within the SELECT. -*/ -void sqlite3SelectPrep( - Parse *pParse, /* The parser context */ - Select *p, /* The SELECT statement being coded. */ - NameContext *pOuterNC /* Name context for container */ -){ - sqlite3 *db; - if( NEVER(p==0) ) return; - db = pParse->db; - if( db->mallocFailed ) return; - if( p->selFlags & SF_HasTypeInfo ) return; - sqlite3SelectExpand(pParse, p); - if( pParse->nErr || db->mallocFailed ) return; - sqlite3ResolveSelectNames(pParse, p, pOuterNC); - if( pParse->nErr || db->mallocFailed ) return; - sqlite3SelectAddTypeInfo(pParse, p); -} - -/* -** Reset the aggregate accumulator. -** -** The aggregate accumulator is a set of memory cells that hold -** intermediate results while calculating an aggregate. This -** routine generates code that stores NULLs in all of those memory -** cells. -*/ -static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){ - Vdbe *v = pParse->pVdbe; - int i; - struct AggInfo_func *pFunc; - int nReg = pAggInfo->nFunc + pAggInfo->nColumn; - if( nReg==0 ) return; -#ifdef SQLITE_DEBUG - /* Verify that all AggInfo registers are within the range specified by - ** AggInfo.mnReg..AggInfo.mxReg */ - assert( nReg==pAggInfo->mxReg-pAggInfo->mnReg+1 ); - for(i=0; i<pAggInfo->nColumn; i++){ - assert( pAggInfo->aCol[i].iMem>=pAggInfo->mnReg - && pAggInfo->aCol[i].iMem<=pAggInfo->mxReg ); - } - for(i=0; i<pAggInfo->nFunc; i++){ - assert( pAggInfo->aFunc[i].iMem>=pAggInfo->mnReg - && pAggInfo->aFunc[i].iMem<=pAggInfo->mxReg ); - } -#endif - sqlite3VdbeAddOp3(v, OP_Null, 0, pAggInfo->mnReg, pAggInfo->mxReg); - for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){ - if( pFunc->iDistinct>=0 ){ - Expr *pE = pFunc->pExpr; - assert( !ExprHasProperty(pE, EP_xIsSelect) ); - if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){ - sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one " - "argument"); - pFunc->iDistinct = -1; - }else{ - KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList, 0, 0); - sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0, - (char*)pKeyInfo, P4_KEYINFO); - } - } - } -} - -/* -** Invoke the OP_AggFinalize opcode for every aggregate function -** in the AggInfo structure. -*/ -static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){ - Vdbe *v = pParse->pVdbe; - int i; - struct AggInfo_func *pF; - for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){ - ExprList *pList = pF->pExpr->x.pList; - assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) ); - sqlite3VdbeAddOp4(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0, 0, - (void*)pF->pFunc, P4_FUNCDEF); - } -} - -/* -** Update the accumulator memory cells for an aggregate based on -** the current cursor position. -*/ -static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){ - Vdbe *v = pParse->pVdbe; - int i; - int regHit = 0; - int addrHitTest = 0; - struct AggInfo_func *pF; - struct AggInfo_col *pC; - - pAggInfo->directMode = 1; - for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){ - int nArg; - int addrNext = 0; - int regAgg; - ExprList *pList = pF->pExpr->x.pList; - assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) ); - if( pList ){ - nArg = pList->nExpr; - regAgg = sqlite3GetTempRange(pParse, nArg); - sqlite3ExprCodeExprList(pParse, pList, regAgg, 0, SQLITE_ECEL_DUP); - }else{ - nArg = 0; - regAgg = 0; - } - if( pF->iDistinct>=0 ){ - addrNext = sqlite3VdbeMakeLabel(v); - testcase( nArg==0 ); /* Error condition */ - testcase( nArg>1 ); /* Also an error */ - codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg); - } - if( pF->pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL ){ - CollSeq *pColl = 0; - struct ExprList_item *pItem; - int j; - assert( pList!=0 ); /* pList!=0 if pF->pFunc has NEEDCOLL */ - for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){ - pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr); - } - if( !pColl ){ - pColl = pParse->db->pDfltColl; - } - if( regHit==0 && pAggInfo->nAccumulator ) regHit = ++pParse->nMem; - sqlite3VdbeAddOp4(v, OP_CollSeq, regHit, 0, 0, (char *)pColl, P4_COLLSEQ); - } - sqlite3VdbeAddOp4(v, OP_AggStep0, 0, regAgg, pF->iMem, - (void*)pF->pFunc, P4_FUNCDEF); - sqlite3VdbeChangeP5(v, (u8)nArg); - sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg); - sqlite3ReleaseTempRange(pParse, regAgg, nArg); - if( addrNext ){ - sqlite3VdbeResolveLabel(v, addrNext); - sqlite3ExprCacheClear(pParse); - } - } - - /* Before populating the accumulator registers, clear the column cache. - ** Otherwise, if any of the required column values are already present - ** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value - ** to pC->iMem. But by the time the value is used, the original register - ** may have been used, invalidating the underlying buffer holding the - ** text or blob value. See ticket [883034dcb5]. - ** - ** Another solution would be to change the OP_SCopy used to copy cached - ** values to an OP_Copy. - */ - if( regHit ){ - addrHitTest = sqlite3VdbeAddOp1(v, OP_If, regHit); VdbeCoverage(v); - } - sqlite3ExprCacheClear(pParse); - for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){ - sqlite3ExprCode(pParse, pC->pExpr, pC->iMem); - } - pAggInfo->directMode = 0; - sqlite3ExprCacheClear(pParse); - if( addrHitTest ){ - sqlite3VdbeJumpHere(v, addrHitTest); - } -} - -/* -** Add a single OP_Explain instruction to the VDBE to explain a simple -** count(*) query ("SELECT count(*) FROM pTab"). -*/ -#ifndef SQLITE_OMIT_EXPLAIN -static void explainSimpleCount( - Parse *pParse, /* Parse context */ - Table *pTab, /* Table being queried */ - Index *pIdx /* Index used to optimize scan, or NULL */ -){ - if( pParse->explain==2 ){ - int bCover = (pIdx!=0 && (HasRowid(pTab) || !IsPrimaryKeyIndex(pIdx))); - char *zEqp = sqlite3MPrintf(pParse->db, "SCAN TABLE %s%s%s", - pTab->zName, - bCover ? " USING COVERING INDEX " : "", - bCover ? pIdx->zName : "" - ); - sqlite3VdbeAddOp4( - pParse->pVdbe, OP_Explain, pParse->iSelectId, 0, 0, zEqp, P4_DYNAMIC - ); - } -} -#else -# define explainSimpleCount(a,b,c) -#endif - -/* -** Generate code for the SELECT statement given in the p argument. -** -** The results are returned according to the SelectDest structure. -** See comments in sqliteInt.h for further information. -** -** This routine returns the number of errors. If any errors are -** encountered, then an appropriate error message is left in -** pParse->zErrMsg. -** -** This routine does NOT free the Select structure passed in. The -** calling function needs to do that. -*/ -int sqlite3Select( - Parse *pParse, /* The parser context */ - Select *p, /* The SELECT statement being coded. */ - SelectDest *pDest /* What to do with the query results */ -){ - int i, j; /* Loop counters */ - WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */ - Vdbe *v; /* The virtual machine under construction */ - int isAgg; /* True for select lists like "count(*)" */ - ExprList *pEList = 0; /* List of columns to extract. */ - SrcList *pTabList; /* List of tables to select from */ - Expr *pWhere; /* The WHERE clause. May be NULL */ - ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */ - Expr *pHaving; /* The HAVING clause. May be NULL */ - int rc = 1; /* Value to return from this function */ - DistinctCtx sDistinct; /* Info on how to code the DISTINCT keyword */ - SortCtx sSort; /* Info on how to code the ORDER BY clause */ - AggInfo sAggInfo; /* Information used by aggregate queries */ - int iEnd; /* Address of the end of the query */ - sqlite3 *db; /* The database connection */ - -#ifndef SQLITE_OMIT_EXPLAIN - int iRestoreSelectId = pParse->iSelectId; - pParse->iSelectId = pParse->iNextSelectId++; -#endif - - db = pParse->db; - if( p==0 || db->mallocFailed || pParse->nErr ){ - return 1; - } - if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1; - memset(&sAggInfo, 0, sizeof(sAggInfo)); -#if SELECTTRACE_ENABLED - pParse->nSelectIndent++; - SELECTTRACE(1,pParse,p, ("begin processing:\n")); - if( sqlite3SelectTrace & 0x100 ){ - sqlite3TreeViewSelect(0, p, 0); - } -#endif - - assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistFifo ); - assert( p->pOrderBy==0 || pDest->eDest!=SRT_Fifo ); - assert( p->pOrderBy==0 || pDest->eDest!=SRT_DistQueue ); - assert( p->pOrderBy==0 || pDest->eDest!=SRT_Queue ); - if( IgnorableOrderby(pDest) ){ - assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union || - pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard || - pDest->eDest==SRT_Queue || pDest->eDest==SRT_DistFifo || - pDest->eDest==SRT_DistQueue || pDest->eDest==SRT_Fifo); - /* If ORDER BY makes no difference in the output then neither does - ** DISTINCT so it can be removed too. */ - sqlite3ExprListDelete(db, p->pOrderBy); - p->pOrderBy = 0; - p->selFlags &= ~SF_Distinct; - } - sqlite3SelectPrep(pParse, p, 0); - memset(&sSort, 0, sizeof(sSort)); - sSort.pOrderBy = p->pOrderBy; - pTabList = p->pSrc; - if( pParse->nErr || db->mallocFailed ){ - goto select_end; - } - assert( p->pEList!=0 ); - isAgg = (p->selFlags & SF_Aggregate)!=0; -#if SELECTTRACE_ENABLED - if( sqlite3SelectTrace & 0x100 ){ - SELECTTRACE(0x100,pParse,p, ("after name resolution:\n")); - sqlite3TreeViewSelect(0, p, 0); - } -#endif - - - /* If writing to memory or generating a set - ** only a single column may be output. - */ -#ifndef SQLITE_OMIT_SUBQUERY - if( checkForMultiColumnSelectError(pParse, pDest, p->pEList->nExpr) ){ - goto select_end; - } -#endif - - /* Try to flatten subqueries in the FROM clause up into the main query - */ -#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) - for(i=0; !p->pPrior && i<pTabList->nSrc; i++){ - struct SrcList_item *pItem = &pTabList->a[i]; - Select *pSub = pItem->pSelect; - int isAggSub; - Table *pTab = pItem->pTab; - if( pSub==0 ) continue; - - /* Catch mismatch in the declared columns of a view and the number of - ** columns in the SELECT on the RHS */ - if( pTab->nCol!=pSub->pEList->nExpr ){ - sqlite3ErrorMsg(pParse, "expected %d columns for '%s' but got %d", - pTab->nCol, pTab->zName, pSub->pEList->nExpr); - goto select_end; - } - - isAggSub = (pSub->selFlags & SF_Aggregate)!=0; - if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){ - /* This subquery can be absorbed into its parent. */ - if( isAggSub ){ - isAgg = 1; - p->selFlags |= SF_Aggregate; - } - i = -1; - } - pTabList = p->pSrc; - if( db->mallocFailed ) goto select_end; - if( !IgnorableOrderby(pDest) ){ - sSort.pOrderBy = p->pOrderBy; - } - } -#endif - - /* Get a pointer the VDBE under construction, allocating a new VDBE if one - ** does not already exist */ - v = sqlite3GetVdbe(pParse); - if( v==0 ) goto select_end; - -#ifndef SQLITE_OMIT_COMPOUND_SELECT - /* Handle compound SELECT statements using the separate multiSelect() - ** procedure. - */ - if( p->pPrior ){ - rc = multiSelect(pParse, p, pDest); - explainSetInteger(pParse->iSelectId, iRestoreSelectId); -#if SELECTTRACE_ENABLED - SELECTTRACE(1,pParse,p,("end compound-select processing\n")); - pParse->nSelectIndent--; -#endif - return rc; - } -#endif - - /* Generate code for all sub-queries in the FROM clause - */ -#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) - for(i=0; i<pTabList->nSrc; i++){ - struct SrcList_item *pItem = &pTabList->a[i]; - SelectDest dest; - Select *pSub = pItem->pSelect; - if( pSub==0 ) continue; - - /* Sometimes the code for a subquery will be generated more than - ** once, if the subquery is part of the WHERE clause in a LEFT JOIN, - ** for example. In that case, do not regenerate the code to manifest - ** a view or the co-routine to implement a view. The first instance - ** is sufficient, though the subroutine to manifest the view does need - ** to be invoked again. */ - if( pItem->addrFillSub ){ - if( pItem->fg.viaCoroutine==0 ){ - sqlite3VdbeAddOp2(v, OP_Gosub, pItem->regReturn, pItem->addrFillSub); - } - continue; - } - - /* Increment Parse.nHeight by the height of the largest expression - ** tree referred to by this, the parent select. The child select - ** may contain expression trees of at most - ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit - ** more conservative than necessary, but much easier than enforcing - ** an exact limit. - */ - pParse->nHeight += sqlite3SelectExprHeight(p); - - /* Make copies of constant WHERE-clause terms in the outer query down - ** inside the subquery. This can help the subquery to run more efficiently. - */ - if( (pItem->fg.jointype & JT_OUTER)==0 - && pushDownWhereTerms(db, pSub, p->pWhere, pItem->iCursor) - ){ -#if SELECTTRACE_ENABLED - if( sqlite3SelectTrace & 0x100 ){ - SELECTTRACE(0x100,pParse,p,("After WHERE-clause push-down:\n")); - sqlite3TreeViewSelect(0, p, 0); - } -#endif - } - - /* Generate code to implement the subquery - */ - if( pTabList->nSrc==1 - && (p->selFlags & SF_All)==0 - && OptimizationEnabled(db, SQLITE_SubqCoroutine) - ){ - /* Implement a co-routine that will return a single row of the result - ** set on each invocation. - */ - int addrTop = sqlite3VdbeCurrentAddr(v)+1; - pItem->regReturn = ++pParse->nMem; - sqlite3VdbeAddOp3(v, OP_InitCoroutine, pItem->regReturn, 0, addrTop); - VdbeComment((v, "%s", pItem->pTab->zName)); - pItem->addrFillSub = addrTop; - sqlite3SelectDestInit(&dest, SRT_Coroutine, pItem->regReturn); - explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId); - sqlite3Select(pParse, pSub, &dest); - pItem->pTab->nRowLogEst = sqlite3LogEst(pSub->nSelectRow); - pItem->fg.viaCoroutine = 1; - pItem->regResult = dest.iSdst; - sqlite3VdbeAddOp1(v, OP_EndCoroutine, pItem->regReturn); - sqlite3VdbeJumpHere(v, addrTop-1); - sqlite3ClearTempRegCache(pParse); - }else{ - /* Generate a subroutine that will fill an ephemeral table with - ** the content of this subquery. pItem->addrFillSub will point - ** to the address of the generated subroutine. pItem->regReturn - ** is a register allocated to hold the subroutine return address - */ - int topAddr; - int onceAddr = 0; - int retAddr; - assert( pItem->addrFillSub==0 ); - pItem->regReturn = ++pParse->nMem; - topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn); - pItem->addrFillSub = topAddr+1; - if( pItem->fg.isCorrelated==0 ){ - /* If the subquery is not correlated and if we are not inside of - ** a trigger, then we only need to compute the value of the subquery - ** once. */ - onceAddr = sqlite3CodeOnce(pParse); VdbeCoverage(v); - VdbeComment((v, "materialize \"%s\"", pItem->pTab->zName)); - }else{ - VdbeNoopComment((v, "materialize \"%s\"", pItem->pTab->zName)); - } - sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor); - explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId); - sqlite3Select(pParse, pSub, &dest); - pItem->pTab->nRowLogEst = sqlite3LogEst(pSub->nSelectRow); - if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr); - retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn); - VdbeComment((v, "end %s", pItem->pTab->zName)); - sqlite3VdbeChangeP1(v, topAddr, retAddr); - sqlite3ClearTempRegCache(pParse); - } - if( db->mallocFailed ) goto select_end; - pParse->nHeight -= sqlite3SelectExprHeight(p); - } -#endif - - /* Various elements of the SELECT copied into local variables for - ** convenience */ - pEList = p->pEList; - pWhere = p->pWhere; - pGroupBy = p->pGroupBy; - pHaving = p->pHaving; - sDistinct.isTnct = (p->selFlags & SF_Distinct)!=0; - -#if SELECTTRACE_ENABLED - if( sqlite3SelectTrace & 0x400 ){ - SELECTTRACE(0x400,pParse,p,("After all FROM-clause analysis:\n")); - sqlite3TreeViewSelect(0, p, 0); - } -#endif - - /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and - ** if the select-list is the same as the ORDER BY list, then this query - ** can be rewritten as a GROUP BY. In other words, this: - ** - ** SELECT DISTINCT xyz FROM ... ORDER BY xyz - ** - ** is transformed to: - ** - ** SELECT xyz FROM ... GROUP BY xyz ORDER BY xyz - ** - ** The second form is preferred as a single index (or temp-table) may be - ** used for both the ORDER BY and DISTINCT processing. As originally - ** written the query must use a temp-table for at least one of the ORDER - ** BY and DISTINCT, and an index or separate temp-table for the other. - */ - if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct - && sqlite3ExprListCompare(sSort.pOrderBy, pEList, -1)==0 - ){ - p->selFlags &= ~SF_Distinct; - pGroupBy = p->pGroupBy = sqlite3ExprListDup(db, pEList, 0); - /* Notice that even thought SF_Distinct has been cleared from p->selFlags, - ** the sDistinct.isTnct is still set. Hence, isTnct represents the - ** original setting of the SF_Distinct flag, not the current setting */ - assert( sDistinct.isTnct ); - } - - /* If there is an ORDER BY clause, then create an ephemeral index to - ** do the sorting. But this sorting ephemeral index might end up - ** being unused if the data can be extracted in pre-sorted order. - ** If that is the case, then the OP_OpenEphemeral instruction will be - ** changed to an OP_Noop once we figure out that the sorting index is - ** not needed. The sSort.addrSortIndex variable is used to facilitate - ** that change. - */ - if( sSort.pOrderBy ){ - KeyInfo *pKeyInfo; - pKeyInfo = keyInfoFromExprList(pParse, sSort.pOrderBy, 0, pEList->nExpr); - sSort.iECursor = pParse->nTab++; - sSort.addrSortIndex = - sqlite3VdbeAddOp4(v, OP_OpenEphemeral, - sSort.iECursor, sSort.pOrderBy->nExpr+1+pEList->nExpr, 0, - (char*)pKeyInfo, P4_KEYINFO - ); - }else{ - sSort.addrSortIndex = -1; - } - - /* If the output is destined for a temporary table, open that table. - */ - if( pDest->eDest==SRT_EphemTab ){ - sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iSDParm, pEList->nExpr); - } - - /* Set the limiter. - */ - iEnd = sqlite3VdbeMakeLabel(v); - p->nSelectRow = LARGEST_INT64; - computeLimitRegisters(pParse, p, iEnd); - if( p->iLimit==0 && sSort.addrSortIndex>=0 ){ - sqlite3VdbeChangeOpcode(v, sSort.addrSortIndex, OP_SorterOpen); - sSort.sortFlags |= SORTFLAG_UseSorter; - } - - /* Open an ephemeral index to use for the distinct set. - */ - if( p->selFlags & SF_Distinct ){ - sDistinct.tabTnct = pParse->nTab++; - sDistinct.addrTnct = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, - sDistinct.tabTnct, 0, 0, - (char*)keyInfoFromExprList(pParse, p->pEList,0,0), - P4_KEYINFO); - sqlite3VdbeChangeP5(v, BTREE_UNORDERED); - sDistinct.eTnctType = WHERE_DISTINCT_UNORDERED; - }else{ - sDistinct.eTnctType = WHERE_DISTINCT_NOOP; - } - - if( !isAgg && pGroupBy==0 ){ - /* No aggregate functions and no GROUP BY clause */ - u16 wctrlFlags = (sDistinct.isTnct ? WHERE_WANT_DISTINCT : 0); - - /* Begin the database scan. */ - pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, sSort.pOrderBy, - p->pEList, wctrlFlags, 0); - if( pWInfo==0 ) goto select_end; - if( sqlite3WhereOutputRowCount(pWInfo) < p->nSelectRow ){ - p->nSelectRow = sqlite3WhereOutputRowCount(pWInfo); - } - if( sDistinct.isTnct && sqlite3WhereIsDistinct(pWInfo) ){ - sDistinct.eTnctType = sqlite3WhereIsDistinct(pWInfo); - } - if( sSort.pOrderBy ){ - sSort.nOBSat = sqlite3WhereIsOrdered(pWInfo); - if( sSort.nOBSat==sSort.pOrderBy->nExpr ){ - sSort.pOrderBy = 0; - } - } - - /* If sorting index that was created by a prior OP_OpenEphemeral - ** instruction ended up not being needed, then change the OP_OpenEphemeral - ** into an OP_Noop. - */ - if( sSort.addrSortIndex>=0 && sSort.pOrderBy==0 ){ - sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex); - } - - /* Use the standard inner loop. */ - selectInnerLoop(pParse, p, pEList, -1, &sSort, &sDistinct, pDest, - sqlite3WhereContinueLabel(pWInfo), - sqlite3WhereBreakLabel(pWInfo)); - - /* End the database scan loop. - */ - sqlite3WhereEnd(pWInfo); - }else{ - /* This case when there exist aggregate functions or a GROUP BY clause - ** or both */ - NameContext sNC; /* Name context for processing aggregate information */ - int iAMem; /* First Mem address for storing current GROUP BY */ - int iBMem; /* First Mem address for previous GROUP BY */ - int iUseFlag; /* Mem address holding flag indicating that at least - ** one row of the input to the aggregator has been - ** processed */ - int iAbortFlag; /* Mem address which causes query abort if positive */ - int groupBySort; /* Rows come from source in GROUP BY order */ - int addrEnd; /* End of processing for this SELECT */ - int sortPTab = 0; /* Pseudotable used to decode sorting results */ - int sortOut = 0; /* Output register from the sorter */ - int orderByGrp = 0; /* True if the GROUP BY and ORDER BY are the same */ - - /* Remove any and all aliases between the result set and the - ** GROUP BY clause. - */ - if( pGroupBy ){ - int k; /* Loop counter */ - struct ExprList_item *pItem; /* For looping over expression in a list */ - - for(k=p->pEList->nExpr, pItem=p->pEList->a; k>0; k--, pItem++){ - pItem->u.x.iAlias = 0; - } - for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){ - pItem->u.x.iAlias = 0; - } - if( p->nSelectRow>100 ) p->nSelectRow = 100; - }else{ - p->nSelectRow = 1; - } - - /* If there is both a GROUP BY and an ORDER BY clause and they are - ** identical, then it may be possible to disable the ORDER BY clause - ** on the grounds that the GROUP BY will cause elements to come out - ** in the correct order. It also may not - the GROUP BY might use a - ** database index that causes rows to be grouped together as required - ** but not actually sorted. Either way, record the fact that the - ** ORDER BY and GROUP BY clauses are the same by setting the orderByGrp - ** variable. */ - if( sqlite3ExprListCompare(pGroupBy, sSort.pOrderBy, -1)==0 ){ - orderByGrp = 1; - } - - /* Create a label to jump to when we want to abort the query */ - addrEnd = sqlite3VdbeMakeLabel(v); - - /* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in - ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the - ** SELECT statement. - */ - memset(&sNC, 0, sizeof(sNC)); - sNC.pParse = pParse; - sNC.pSrcList = pTabList; - sNC.pAggInfo = &sAggInfo; - sAggInfo.mnReg = pParse->nMem+1; - sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr : 0; - sAggInfo.pGroupBy = pGroupBy; - sqlite3ExprAnalyzeAggList(&sNC, pEList); - sqlite3ExprAnalyzeAggList(&sNC, sSort.pOrderBy); - if( pHaving ){ - sqlite3ExprAnalyzeAggregates(&sNC, pHaving); - } - sAggInfo.nAccumulator = sAggInfo.nColumn; - for(i=0; i<sAggInfo.nFunc; i++){ - assert( !ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_xIsSelect) ); - sNC.ncFlags |= NC_InAggFunc; - sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList); - sNC.ncFlags &= ~NC_InAggFunc; - } - sAggInfo.mxReg = pParse->nMem; - if( db->mallocFailed ) goto select_end; - - /* Processing for aggregates with GROUP BY is very different and - ** much more complex than aggregates without a GROUP BY. - */ - if( pGroupBy ){ - KeyInfo *pKeyInfo; /* Keying information for the group by clause */ - int addr1; /* A-vs-B comparision jump */ - int addrOutputRow; /* Start of subroutine that outputs a result row */ - int regOutputRow; /* Return address register for output subroutine */ - int addrSetAbort; /* Set the abort flag and return */ - int addrTopOfLoop; /* Top of the input loop */ - int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */ - int addrReset; /* Subroutine for resetting the accumulator */ - int regReset; /* Return address register for reset subroutine */ - - /* If there is a GROUP BY clause we might need a sorting index to - ** implement it. Allocate that sorting index now. If it turns out - ** that we do not need it after all, the OP_SorterOpen instruction - ** will be converted into a Noop. - */ - sAggInfo.sortingIdx = pParse->nTab++; - pKeyInfo = keyInfoFromExprList(pParse, pGroupBy, 0, sAggInfo.nColumn); - addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen, - sAggInfo.sortingIdx, sAggInfo.nSortingColumn, - 0, (char*)pKeyInfo, P4_KEYINFO); - - /* Initialize memory locations used by GROUP BY aggregate processing - */ - iUseFlag = ++pParse->nMem; - iAbortFlag = ++pParse->nMem; - regOutputRow = ++pParse->nMem; - addrOutputRow = sqlite3VdbeMakeLabel(v); - regReset = ++pParse->nMem; - addrReset = sqlite3VdbeMakeLabel(v); - iAMem = pParse->nMem + 1; - pParse->nMem += pGroupBy->nExpr; - iBMem = pParse->nMem + 1; - pParse->nMem += pGroupBy->nExpr; - sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag); - VdbeComment((v, "clear abort flag")); - sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag); - VdbeComment((v, "indicate accumulator empty")); - sqlite3VdbeAddOp3(v, OP_Null, 0, iAMem, iAMem+pGroupBy->nExpr-1); - - /* Begin a loop that will extract all source rows in GROUP BY order. - ** This might involve two separate loops with an OP_Sort in between, or - ** it might be a single loop that uses an index to extract information - ** in the right order to begin with. - */ - sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset); - pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pGroupBy, 0, - WHERE_GROUPBY | (orderByGrp ? WHERE_SORTBYGROUP : 0), 0 - ); - if( pWInfo==0 ) goto select_end; - if( sqlite3WhereIsOrdered(pWInfo)==pGroupBy->nExpr ){ - /* The optimizer is able to deliver rows in group by order so - ** we do not have to sort. The OP_OpenEphemeral table will be - ** cancelled later because we still need to use the pKeyInfo - */ - groupBySort = 0; - }else{ - /* Rows are coming out in undetermined order. We have to push - ** each row into a sorting index, terminate the first loop, - ** then loop over the sorting index in order to get the output - ** in sorted order - */ - int regBase; - int regRecord; - int nCol; - int nGroupBy; - - explainTempTable(pParse, - (sDistinct.isTnct && (p->selFlags&SF_Distinct)==0) ? - "DISTINCT" : "GROUP BY"); - - groupBySort = 1; - nGroupBy = pGroupBy->nExpr; - nCol = nGroupBy; - j = nGroupBy; - for(i=0; i<sAggInfo.nColumn; i++){ - if( sAggInfo.aCol[i].iSorterColumn>=j ){ - nCol++; - j++; - } - } - regBase = sqlite3GetTempRange(pParse, nCol); - sqlite3ExprCacheClear(pParse); - sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0, 0); - j = nGroupBy; - for(i=0; i<sAggInfo.nColumn; i++){ - struct AggInfo_col *pCol = &sAggInfo.aCol[i]; - if( pCol->iSorterColumn>=j ){ - int r1 = j + regBase; - int r2; - - r2 = sqlite3ExprCodeGetColumn(pParse, - pCol->pTab, pCol->iColumn, pCol->iTable, r1, 0); - if( r1!=r2 ){ - sqlite3VdbeAddOp2(v, OP_SCopy, r2, r1); - } - j++; - } - } - regRecord = sqlite3GetTempReg(pParse); - sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord); - sqlite3VdbeAddOp2(v, OP_SorterInsert, sAggInfo.sortingIdx, regRecord); - sqlite3ReleaseTempReg(pParse, regRecord); - sqlite3ReleaseTempRange(pParse, regBase, nCol); - sqlite3WhereEnd(pWInfo); - sAggInfo.sortingIdxPTab = sortPTab = pParse->nTab++; - sortOut = sqlite3GetTempReg(pParse); - sqlite3VdbeAddOp3(v, OP_OpenPseudo, sortPTab, sortOut, nCol); - sqlite3VdbeAddOp2(v, OP_SorterSort, sAggInfo.sortingIdx, addrEnd); - VdbeComment((v, "GROUP BY sort")); VdbeCoverage(v); - sAggInfo.useSortingIdx = 1; - sqlite3ExprCacheClear(pParse); - - } - - /* If the index or temporary table used by the GROUP BY sort - ** will naturally deliver rows in the order required by the ORDER BY - ** clause, cancel the ephemeral table open coded earlier. - ** - ** This is an optimization - the correct answer should result regardless. - ** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER to - ** disable this optimization for testing purposes. */ - if( orderByGrp && OptimizationEnabled(db, SQLITE_GroupByOrder) - && (groupBySort || sqlite3WhereIsSorted(pWInfo)) - ){ - sSort.pOrderBy = 0; - sqlite3VdbeChangeToNoop(v, sSort.addrSortIndex); - } - - /* Evaluate the current GROUP BY terms and store in b0, b1, b2... - ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth) - ** Then compare the current GROUP BY terms against the GROUP BY terms - ** from the previous row currently stored in a0, a1, a2... - */ - addrTopOfLoop = sqlite3VdbeCurrentAddr(v); - sqlite3ExprCacheClear(pParse); - if( groupBySort ){ - sqlite3VdbeAddOp3(v, OP_SorterData, sAggInfo.sortingIdx, - sortOut, sortPTab); - } - for(j=0; j<pGroupBy->nExpr; j++){ - if( groupBySort ){ - sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j); - }else{ - sAggInfo.directMode = 1; - sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j); - } - } - sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr, - (char*)sqlite3KeyInfoRef(pKeyInfo), P4_KEYINFO); - addr1 = sqlite3VdbeCurrentAddr(v); - sqlite3VdbeAddOp3(v, OP_Jump, addr1+1, 0, addr1+1); VdbeCoverage(v); - - /* Generate code that runs whenever the GROUP BY changes. - ** Changes in the GROUP BY are detected by the previous code - ** block. If there were no changes, this block is skipped. - ** - ** This code copies current group by terms in b0,b1,b2,... - ** over to a0,a1,a2. It then calls the output subroutine - ** and resets the aggregate accumulator registers in preparation - ** for the next GROUP BY batch. - */ - sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr); - sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow); - VdbeComment((v, "output one row")); - sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd); VdbeCoverage(v); - VdbeComment((v, "check abort flag")); - sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset); - VdbeComment((v, "reset accumulator")); - - /* Update the aggregate accumulators based on the content of - ** the current row - */ - sqlite3VdbeJumpHere(v, addr1); - updateAccumulator(pParse, &sAggInfo); - sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag); - VdbeComment((v, "indicate data in accumulator")); - - /* End of the loop - */ - if( groupBySort ){ - sqlite3VdbeAddOp2(v, OP_SorterNext, sAggInfo.sortingIdx, addrTopOfLoop); - VdbeCoverage(v); - }else{ - sqlite3WhereEnd(pWInfo); - sqlite3VdbeChangeToNoop(v, addrSortingIdx); - } - - /* Output the final row of result - */ - sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow); - VdbeComment((v, "output final row")); - - /* Jump over the subroutines - */ - sqlite3VdbeGoto(v, addrEnd); - - /* Generate a subroutine that outputs a single row of the result - ** set. This subroutine first looks at the iUseFlag. If iUseFlag - ** is less than or equal to zero, the subroutine is a no-op. If - ** the processing calls for the query to abort, this subroutine - ** increments the iAbortFlag memory location before returning in - ** order to signal the caller to abort. - */ - addrSetAbort = sqlite3VdbeCurrentAddr(v); - sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag); - VdbeComment((v, "set abort flag")); - sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); - sqlite3VdbeResolveLabel(v, addrOutputRow); - addrOutputRow = sqlite3VdbeCurrentAddr(v); - sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2); - VdbeCoverage(v); - VdbeComment((v, "Groupby result generator entry point")); - sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); - finalizeAggFunctions(pParse, &sAggInfo); - sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL); - selectInnerLoop(pParse, p, p->pEList, -1, &sSort, - &sDistinct, pDest, - addrOutputRow+1, addrSetAbort); - sqlite3VdbeAddOp1(v, OP_Return, regOutputRow); - VdbeComment((v, "end groupby result generator")); - - /* Generate a subroutine that will reset the group-by accumulator - */ - sqlite3VdbeResolveLabel(v, addrReset); - resetAccumulator(pParse, &sAggInfo); - sqlite3VdbeAddOp1(v, OP_Return, regReset); - - } /* endif pGroupBy. Begin aggregate queries without GROUP BY: */ - else { - ExprList *pDel = 0; -#ifndef SQLITE_OMIT_BTREECOUNT - Table *pTab; - if( (pTab = isSimpleCount(p, &sAggInfo))!=0 ){ - /* If isSimpleCount() returns a pointer to a Table structure, then - ** the SQL statement is of the form: - ** - ** SELECT count(*) FROM <tbl> - ** - ** where the Table structure returned represents table <tbl>. - ** - ** This statement is so common that it is optimized specially. The - ** OP_Count instruction is executed either on the intkey table that - ** contains the data for table <tbl> or on one of its indexes. It - ** is better to execute the op on an index, as indexes are almost - ** always spread across less pages than their corresponding tables. - */ - const int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema); - const int iCsr = pParse->nTab++; /* Cursor to scan b-tree */ - Index *pIdx; /* Iterator variable */ - KeyInfo *pKeyInfo = 0; /* Keyinfo for scanned index */ - Index *pBest = 0; /* Best index found so far */ - int iRoot = pTab->tnum; /* Root page of scanned b-tree */ - - sqlite3CodeVerifySchema(pParse, iDb); - sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName); - - /* Search for the index that has the lowest scan cost. - ** - ** (2011-04-15) Do not do a full scan of an unordered index. - ** - ** (2013-10-03) Do not count the entries in a partial index. - ** - ** In practice the KeyInfo structure will not be used. It is only - ** passed to keep OP_OpenRead happy. - */ - if( !HasRowid(pTab) ) pBest = sqlite3PrimaryKeyIndex(pTab); - for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ - if( pIdx->bUnordered==0 - && pIdx->szIdxRow<pTab->szTabRow - && pIdx->pPartIdxWhere==0 - && (!pBest || pIdx->szIdxRow<pBest->szIdxRow) - ){ - pBest = pIdx; - } - } - if( pBest ){ - iRoot = pBest->tnum; - pKeyInfo = sqlite3KeyInfoOfIndex(pParse, pBest); - } - - /* Open a read-only cursor, execute the OP_Count, close the cursor. */ - sqlite3VdbeAddOp4Int(v, OP_OpenRead, iCsr, iRoot, iDb, 1); - if( pKeyInfo ){ - sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO); - } - sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem); - sqlite3VdbeAddOp1(v, OP_Close, iCsr); - explainSimpleCount(pParse, pTab, pBest); - }else -#endif /* SQLITE_OMIT_BTREECOUNT */ - { - /* Check if the query is of one of the following forms: - ** - ** SELECT min(x) FROM ... - ** SELECT max(x) FROM ... - ** - ** If it is, then ask the code in where.c to attempt to sort results - ** as if there was an "ORDER ON x" or "ORDER ON x DESC" clause. - ** If where.c is able to produce results sorted in this order, then - ** add vdbe code to break out of the processing loop after the - ** first iteration (since the first iteration of the loop is - ** guaranteed to operate on the row with the minimum or maximum - ** value of x, the only row required). - ** - ** A special flag must be passed to sqlite3WhereBegin() to slightly - ** modify behavior as follows: - ** - ** + If the query is a "SELECT min(x)", then the loop coded by - ** where.c should not iterate over any values with a NULL value - ** for x. - ** - ** + The optimizer code in where.c (the thing that decides which - ** index or indices to use) should place a different priority on - ** satisfying the 'ORDER BY' clause than it does in other cases. - ** Refer to code and comments in where.c for details. - */ - ExprList *pMinMax = 0; - u8 flag = WHERE_ORDERBY_NORMAL; - - assert( p->pGroupBy==0 ); - assert( flag==0 ); - if( p->pHaving==0 ){ - flag = minMaxQuery(&sAggInfo, &pMinMax); - } - assert( flag==0 || (pMinMax!=0 && pMinMax->nExpr==1) ); - - if( flag ){ - pMinMax = sqlite3ExprListDup(db, pMinMax, 0); - pDel = pMinMax; - if( pMinMax && !db->mallocFailed ){ - pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0; - pMinMax->a[0].pExpr->op = TK_COLUMN; - } - } - - /* This case runs if the aggregate has no GROUP BY clause. The - ** processing is much simpler since there is only a single row - ** of output. - */ - resetAccumulator(pParse, &sAggInfo); - pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMax,0,flag,0); - if( pWInfo==0 ){ - sqlite3ExprListDelete(db, pDel); - goto select_end; - } - updateAccumulator(pParse, &sAggInfo); - assert( pMinMax==0 || pMinMax->nExpr==1 ); - if( sqlite3WhereIsOrdered(pWInfo)>0 ){ - sqlite3VdbeGoto(v, sqlite3WhereBreakLabel(pWInfo)); - VdbeComment((v, "%s() by index", - (flag==WHERE_ORDERBY_MIN?"min":"max"))); - } - sqlite3WhereEnd(pWInfo); - finalizeAggFunctions(pParse, &sAggInfo); - } - - sSort.pOrderBy = 0; - sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL); - selectInnerLoop(pParse, p, p->pEList, -1, 0, 0, - pDest, addrEnd, addrEnd); - sqlite3ExprListDelete(db, pDel); - } - sqlite3VdbeResolveLabel(v, addrEnd); - - } /* endif aggregate query */ - - if( sDistinct.eTnctType==WHERE_DISTINCT_UNORDERED ){ - explainTempTable(pParse, "DISTINCT"); - } - - /* If there is an ORDER BY clause, then we need to sort the results - ** and send them to the callback one by one. - */ - if( sSort.pOrderBy ){ - explainTempTable(pParse, - sSort.nOBSat>0 ? "RIGHT PART OF ORDER BY":"ORDER BY"); - generateSortTail(pParse, p, &sSort, pEList->nExpr, pDest); - } - - /* Jump here to skip this query - */ - sqlite3VdbeResolveLabel(v, iEnd); - - /* The SELECT has been coded. If there is an error in the Parse structure, - ** set the return code to 1. Otherwise 0. */ - rc = (pParse->nErr>0); - - /* Control jumps to here if an error is encountered above, or upon - ** successful coding of the SELECT. - */ -select_end: - explainSetInteger(pParse->iSelectId, iRestoreSelectId); - - /* Identify column names if results of the SELECT are to be output. - */ - if( rc==SQLITE_OK && pDest->eDest==SRT_Output ){ - generateColumnNames(pParse, pTabList, pEList); - } - - sqlite3DbFree(db, sAggInfo.aCol); - sqlite3DbFree(db, sAggInfo.aFunc); -#if SELECTTRACE_ENABLED - SELECTTRACE(1,pParse,p,("end processing\n")); - pParse->nSelectIndent--; -#endif - return rc; -} |