/* ** 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 module contains C code that generates VDBE code used to process ** the WHERE clause of SQL statements. This module is responsible for ** generating the code that loops through a table looking for applicable ** rows. Indices are selected and used to speed the search when doing ** so is applicable. Because this module is responsible for selecting ** indices, you might also think of this module as the "query optimizer". */ #include "sqliteInt.h" #include "whereInt.h" /* ** Extra information appended to the end of sqlite3_index_info but not ** visible to the xBestIndex function, at least not directly. The ** sqlite3_vtab_collation() interface knows how to reach it, however. ** ** This object is not an API and can be changed from one release to the ** next. As long as allocateIndexInfo() and sqlite3_vtab_collation() ** agree on the structure, all will be well. */ typedef struct HiddenIndexInfo HiddenIndexInfo; struct HiddenIndexInfo { WhereClause *pWC; /* The Where clause being analyzed */ Parse *pParse; /* The parsing context */ int eDistinct; /* Value to return from sqlite3_vtab_distinct() */ u32 mIn; /* Mask of terms that are IN (...) */ u32 mHandleIn; /* Terms that vtab will handle as IN (...) */ sqlite3_value *aRhs[1]; /* RHS values for constraints. MUST BE LAST ** because extra space is allocated to hold up ** to nTerm such values */ }; /* Forward declaration of methods */ static int whereLoopResize(sqlite3*, WhereLoop*, int); /* ** Return the estimated number of output rows from a WHERE clause */ LogEst sqlite3WhereOutputRowCount(WhereInfo *pWInfo){ return pWInfo->nRowOut; } /* ** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this ** WHERE clause returns outputs for DISTINCT processing. */ int sqlite3WhereIsDistinct(WhereInfo *pWInfo){ return pWInfo->eDistinct; } /* ** Return the number of ORDER BY terms that are satisfied by the ** WHERE clause. A return of 0 means that the output must be ** completely sorted. A return equal to the number of ORDER BY ** terms means that no sorting is needed at all. A return that ** is positive but less than the number of ORDER BY terms means that ** block sorting is required. */ int sqlite3WhereIsOrdered(WhereInfo *pWInfo){ return pWInfo->nOBSat<0 ? 0 : pWInfo->nOBSat; } /* ** In the ORDER BY LIMIT optimization, if the inner-most loop is known ** to emit rows in increasing order, and if the last row emitted by the ** inner-most loop did not fit within the sorter, then we can skip all ** subsequent rows for the current iteration of the inner loop (because they ** will not fit in the sorter either) and continue with the second inner ** loop - the loop immediately outside the inner-most. ** ** When a row does not fit in the sorter (because the sorter already ** holds LIMIT+OFFSET rows that are smaller), then a jump is made to the ** label returned by this function. ** ** If the ORDER BY LIMIT optimization applies, the jump destination should ** be the continuation for the second-inner-most loop. If the ORDER BY ** LIMIT optimization does not apply, then the jump destination should ** be the continuation for the inner-most loop. ** ** It is always safe for this routine to return the continuation of the ** inner-most loop, in the sense that a correct answer will result. ** Returning the continuation the second inner loop is an optimization ** that might make the code run a little faster, but should not change ** the final answer. */ int sqlite3WhereOrderByLimitOptLabel(WhereInfo *pWInfo){ WhereLevel *pInner; if( !pWInfo->bOrderedInnerLoop ){ /* The ORDER BY LIMIT optimization does not apply. Jump to the ** continuation of the inner-most loop. */ return pWInfo->iContinue; } pInner = &pWInfo->a[pWInfo->nLevel-1]; assert( pInner->addrNxt!=0 ); return pInner->pRJ ? pWInfo->iContinue : pInner->addrNxt; } /* ** While generating code for the min/max optimization, after handling ** the aggregate-step call to min() or max(), check to see if any ** additional looping is required. If the output order is such that ** we are certain that the correct answer has already been found, then ** code an OP_Goto to by pass subsequent processing. ** ** Any extra OP_Goto that is coded here is an optimization. The ** correct answer should be obtained regardless. This OP_Goto just ** makes the answer appear faster. */ void sqlite3WhereMinMaxOptEarlyOut(Vdbe *v, WhereInfo *pWInfo){ WhereLevel *pInner; int i; if( !pWInfo->bOrderedInnerLoop ) return; if( pWInfo->nOBSat==0 ) return; for(i=pWInfo->nLevel-1; i>=0; i--){ pInner = &pWInfo->a[i]; if( (pInner->pWLoop->wsFlags & WHERE_COLUMN_IN)!=0 ){ sqlite3VdbeGoto(v, pInner->addrNxt); return; } } sqlite3VdbeGoto(v, pWInfo->iBreak); } /* ** Return the VDBE address or label to jump to in order to continue ** immediately with the next row of a WHERE clause. */ int sqlite3WhereContinueLabel(WhereInfo *pWInfo){ assert( pWInfo->iContinue!=0 ); return pWInfo->iContinue; } /* ** Return the VDBE address or label to jump to in order to break ** out of a WHERE loop. */ int sqlite3WhereBreakLabel(WhereInfo *pWInfo){ return pWInfo->iBreak; } /* ** Return ONEPASS_OFF (0) if an UPDATE or DELETE statement is unable to ** operate directly on the rowids returned by a WHERE clause. Return ** ONEPASS_SINGLE (1) if the statement can operation directly because only ** a single row is to be changed. Return ONEPASS_MULTI (2) if the one-pass ** optimization can be used on multiple ** ** If the ONEPASS optimization is used (if this routine returns true) ** then also write the indices of open cursors used by ONEPASS ** into aiCur[0] and aiCur[1]. iaCur[0] gets the cursor of the data ** table and iaCur[1] gets the cursor used by an auxiliary index. ** Either value may be -1, indicating that cursor is not used. ** Any cursors returned will have been opened for writing. ** ** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is ** unable to use the ONEPASS optimization. */ int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){ memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2); #ifdef WHERETRACE_ENABLED if( sqlite3WhereTrace && pWInfo->eOnePass!=ONEPASS_OFF ){ sqlite3DebugPrintf("%s cursors: %d %d\n", pWInfo->eOnePass==ONEPASS_SINGLE ? "ONEPASS_SINGLE" : "ONEPASS_MULTI", aiCur[0], aiCur[1]); } #endif return pWInfo->eOnePass; } /* ** Return TRUE if the WHERE loop uses the OP_DeferredSeek opcode to move ** the data cursor to the row selected by the index cursor. */ int sqlite3WhereUsesDeferredSeek(WhereInfo *pWInfo){ return pWInfo->bDeferredSeek; } /* ** Move the content of pSrc into pDest */ static void whereOrMove(WhereOrSet *pDest, WhereOrSet *pSrc){ pDest->n = pSrc->n; memcpy(pDest->a, pSrc->a, pDest->n*sizeof(pDest->a[0])); } /* ** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet. ** ** The new entry might overwrite an existing entry, or it might be ** appended, or it might be discarded. Do whatever is the right thing ** so that pSet keeps the N_OR_COST best entries seen so far. */ static int whereOrInsert( WhereOrSet *pSet, /* The WhereOrSet to be updated */ Bitmask prereq, /* Prerequisites of the new entry */ LogEst rRun, /* Run-cost of the new entry */ LogEst nOut /* Number of outputs for the new entry */ ){ u16 i; WhereOrCost *p; for(i=pSet->n, p=pSet->a; i>0; i--, p++){ if( rRun<=p->rRun && (prereq & p->prereq)==prereq ){ goto whereOrInsert_done; } if( p->rRun<=rRun && (p->prereq & prereq)==p->prereq ){ return 0; } } if( pSet->na[pSet->n++]; p->nOut = nOut; }else{ p = pSet->a; for(i=1; in; i++){ if( p->rRun>pSet->a[i].rRun ) p = pSet->a + i; } if( p->rRun<=rRun ) return 0; } whereOrInsert_done: p->prereq = prereq; p->rRun = rRun; if( p->nOut>nOut ) p->nOut = nOut; return 1; } /* ** Return the bitmask for the given cursor number. Return 0 if ** iCursor is not in the set. */ Bitmask sqlite3WhereGetMask(WhereMaskSet *pMaskSet, int iCursor){ int i; assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 ); assert( pMaskSet->n>0 || pMaskSet->ix[0]<0 ); assert( iCursor>=-1 ); if( pMaskSet->ix[0]==iCursor ){ return 1; } for(i=1; in; i++){ if( pMaskSet->ix[i]==iCursor ){ return MASKBIT(i); } } return 0; } /* Allocate memory that is automatically freed when pWInfo is freed. */ void *sqlite3WhereMalloc(WhereInfo *pWInfo, u64 nByte){ WhereMemBlock *pBlock; pBlock = sqlite3DbMallocRawNN(pWInfo->pParse->db, nByte+sizeof(*pBlock)); if( pBlock ){ pBlock->pNext = pWInfo->pMemToFree; pBlock->sz = nByte; pWInfo->pMemToFree = pBlock; pBlock++; } return (void*)pBlock; } void *sqlite3WhereRealloc(WhereInfo *pWInfo, void *pOld, u64 nByte){ void *pNew = sqlite3WhereMalloc(pWInfo, nByte); if( pNew && pOld ){ WhereMemBlock *pOldBlk = (WhereMemBlock*)pOld; pOldBlk--; assert( pOldBlk->szsz); } return pNew; } /* ** Create a new mask for cursor iCursor. ** ** There is one cursor per table in the FROM clause. The number of ** tables in the FROM clause is limited by a test early in the ** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[] ** array will never overflow. */ static void createMask(WhereMaskSet *pMaskSet, int iCursor){ assert( pMaskSet->n < ArraySize(pMaskSet->ix) ); pMaskSet->ix[pMaskSet->n++] = iCursor; } /* ** If the right-hand branch of the expression is a TK_COLUMN, then return ** a pointer to the right-hand branch. Otherwise, return NULL. */ static Expr *whereRightSubexprIsColumn(Expr *p){ p = sqlite3ExprSkipCollateAndLikely(p->pRight); if( ALWAYS(p!=0) && p->op==TK_COLUMN && !ExprHasProperty(p, EP_FixedCol) ){ return p; } return 0; } /* ** Advance to the next WhereTerm that matches according to the criteria ** established when the pScan object was initialized by whereScanInit(). ** Return NULL if there are no more matching WhereTerms. */ static WhereTerm *whereScanNext(WhereScan *pScan){ int iCur; /* The cursor on the LHS of the term */ i16 iColumn; /* The column on the LHS of the term. -1 for IPK */ Expr *pX; /* An expression being tested */ WhereClause *pWC; /* Shorthand for pScan->pWC */ WhereTerm *pTerm; /* The term being tested */ int k = pScan->k; /* Where to start scanning */ assert( pScan->iEquiv<=pScan->nEquiv ); pWC = pScan->pWC; while(1){ iColumn = pScan->aiColumn[pScan->iEquiv-1]; iCur = pScan->aiCur[pScan->iEquiv-1]; assert( pWC!=0 ); assert( iCur>=0 ); do{ for(pTerm=pWC->a+k; knTerm; k++, pTerm++){ assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 || pTerm->leftCursor<0 ); if( pTerm->leftCursor==iCur && pTerm->u.x.leftColumn==iColumn && (iColumn!=XN_EXPR || sqlite3ExprCompareSkip(pTerm->pExpr->pLeft, pScan->pIdxExpr,iCur)==0) && (pScan->iEquiv<=1 || !ExprHasProperty(pTerm->pExpr, EP_OuterON)) ){ if( (pTerm->eOperator & WO_EQUIV)!=0 && pScan->nEquivaiCur) && (pX = whereRightSubexprIsColumn(pTerm->pExpr))!=0 ){ int j; for(j=0; jnEquiv; j++){ if( pScan->aiCur[j]==pX->iTable && pScan->aiColumn[j]==pX->iColumn ){ break; } } if( j==pScan->nEquiv ){ pScan->aiCur[j] = pX->iTable; pScan->aiColumn[j] = pX->iColumn; pScan->nEquiv++; } } if( (pTerm->eOperator & pScan->opMask)!=0 ){ /* Verify the affinity and collating sequence match */ if( pScan->zCollName && (pTerm->eOperator & WO_ISNULL)==0 ){ CollSeq *pColl; Parse *pParse = pWC->pWInfo->pParse; pX = pTerm->pExpr; if( !sqlite3IndexAffinityOk(pX, pScan->idxaff) ){ continue; } assert(pX->pLeft); pColl = sqlite3ExprCompareCollSeq(pParse, pX); if( pColl==0 ) pColl = pParse->db->pDfltColl; if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){ continue; } } if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0 && (pX = pTerm->pExpr->pRight, ALWAYS(pX!=0)) && pX->op==TK_COLUMN && pX->iTable==pScan->aiCur[0] && pX->iColumn==pScan->aiColumn[0] ){ testcase( pTerm->eOperator & WO_IS ); continue; } pScan->pWC = pWC; pScan->k = k+1; #ifdef WHERETRACE_ENABLED if( sqlite3WhereTrace & 0x20000 ){ int ii; sqlite3DebugPrintf("SCAN-TERM %p: nEquiv=%d", pTerm, pScan->nEquiv); for(ii=0; iinEquiv; ii++){ sqlite3DebugPrintf(" {%d:%d}", pScan->aiCur[ii], pScan->aiColumn[ii]); } sqlite3DebugPrintf("\n"); } #endif return pTerm; } } } pWC = pWC->pOuter; k = 0; }while( pWC!=0 ); if( pScan->iEquiv>=pScan->nEquiv ) break; pWC = pScan->pOrigWC; k = 0; pScan->iEquiv++; } return 0; } /* ** This is whereScanInit() for the case of an index on an expression. ** It is factored out into a separate tail-recursion subroutine so that ** the normal whereScanInit() routine, which is a high-runner, does not ** need to push registers onto the stack as part of its prologue. */ static SQLITE_NOINLINE WhereTerm *whereScanInitIndexExpr(WhereScan *pScan){ pScan->idxaff = sqlite3ExprAffinity(pScan->pIdxExpr); return whereScanNext(pScan); } /* ** Initialize a WHERE clause scanner object. Return a pointer to the ** first match. Return NULL if there are no matches. ** ** The scanner will be searching the WHERE clause pWC. It will look ** for terms of the form "X " where X is column iColumn of table ** iCur. Or if pIdx!=0 then X is column iColumn of index pIdx. pIdx ** must be one of the indexes of table iCur. ** ** The must be one of the operators described by opMask. ** ** If the search is for X and the WHERE clause contains terms of the ** form X=Y then this routine might also return terms of the form ** "Y ". The number of levels of transitivity is limited, ** but is enough to handle most commonly occurring SQL statements. ** ** If X is not the INTEGER PRIMARY KEY then X must be compatible with ** index pIdx. */ static WhereTerm *whereScanInit( WhereScan *pScan, /* The WhereScan object being initialized */ WhereClause *pWC, /* The WHERE clause to be scanned */ int iCur, /* Cursor to scan for */ int iColumn, /* Column to scan for */ u32 opMask, /* Operator(s) to scan for */ Index *pIdx /* Must be compatible with this index */ ){ pScan->pOrigWC = pWC; pScan->pWC = pWC; pScan->pIdxExpr = 0; pScan->idxaff = 0; pScan->zCollName = 0; pScan->opMask = opMask; pScan->k = 0; pScan->aiCur[0] = iCur; pScan->nEquiv = 1; pScan->iEquiv = 1; if( pIdx ){ int j = iColumn; iColumn = pIdx->aiColumn[j]; if( iColumn==pIdx->pTable->iPKey ){ iColumn = XN_ROWID; }else if( iColumn>=0 ){ pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity; pScan->zCollName = pIdx->azColl[j]; }else if( iColumn==XN_EXPR ){ pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr; pScan->zCollName = pIdx->azColl[j]; pScan->aiColumn[0] = XN_EXPR; return whereScanInitIndexExpr(pScan); } }else if( iColumn==XN_EXPR ){ return 0; } pScan->aiColumn[0] = iColumn; return whereScanNext(pScan); } /* ** Search for a term in the WHERE clause that is of the form "X " ** where X is a reference to the iColumn of table iCur or of index pIdx ** if pIdx!=0 and is one of the WO_xx operator codes specified by ** the op parameter. Return a pointer to the term. Return 0 if not found. ** ** If pIdx!=0 then it must be one of the indexes of table iCur. ** Search for terms matching the iColumn-th column of pIdx ** rather than the iColumn-th column of table iCur. ** ** The term returned might by Y= if there is another constraint in ** the WHERE clause that specifies that X=Y. Any such constraints will be ** identified by the WO_EQUIV bit in the pTerm->eOperator field. The ** aiCur[]/iaColumn[] arrays hold X and all its equivalents. There are 11 ** slots in aiCur[]/aiColumn[] so that means we can look for X plus up to 10 ** other equivalent values. Hence a search for X will return if X=A1 ** and A1=A2 and A2=A3 and ... and A9=A10 and A10=. ** ** If there are multiple terms in the WHERE clause of the form "X " ** then try for the one with no dependencies on - in other words where ** is a constant expression of some kind. Only return entries of ** the form "X Y" where Y is a column in another table if no terms of ** the form "X " exist. If no terms with a constant RHS ** exist, try to return a term that does not use WO_EQUIV. */ WhereTerm *sqlite3WhereFindTerm( WhereClause *pWC, /* The WHERE clause to be searched */ int iCur, /* Cursor number of LHS */ int iColumn, /* Column number of LHS */ Bitmask notReady, /* RHS must not overlap with this mask */ u32 op, /* Mask of WO_xx values describing operator */ Index *pIdx /* Must be compatible with this index, if not NULL */ ){ WhereTerm *pResult = 0; WhereTerm *p; WhereScan scan; p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx); op &= WO_EQ|WO_IS; while( p ){ if( (p->prereqRight & notReady)==0 ){ if( p->prereqRight==0 && (p->eOperator&op)!=0 ){ testcase( p->eOperator & WO_IS ); return p; } if( pResult==0 ) pResult = p; } p = whereScanNext(&scan); } return pResult; } /* ** This function searches pList for an entry that matches the iCol-th column ** of index pIdx. ** ** If such an expression is found, its index in pList->a[] is returned. If ** no expression is found, -1 is returned. */ static int findIndexCol( Parse *pParse, /* Parse context */ ExprList *pList, /* Expression list to search */ int iBase, /* Cursor for table associated with pIdx */ Index *pIdx, /* Index to match column of */ int iCol /* Column of index to match */ ){ int i; const char *zColl = pIdx->azColl[iCol]; for(i=0; inExpr; i++){ Expr *p = sqlite3ExprSkipCollateAndLikely(pList->a[i].pExpr); if( ALWAYS(p!=0) && (p->op==TK_COLUMN || p->op==TK_AGG_COLUMN) && p->iColumn==pIdx->aiColumn[iCol] && p->iTable==iBase ){ CollSeq *pColl = sqlite3ExprNNCollSeq(pParse, pList->a[i].pExpr); if( 0==sqlite3StrICmp(pColl->zName, zColl) ){ return i; } } } return -1; } /* ** Return TRUE if the iCol-th column of index pIdx is NOT NULL */ static int indexColumnNotNull(Index *pIdx, int iCol){ int j; assert( pIdx!=0 ); assert( iCol>=0 && iColnColumn ); j = pIdx->aiColumn[iCol]; if( j>=0 ){ return pIdx->pTable->aCol[j].notNull; }else if( j==(-1) ){ return 1; }else{ assert( j==(-2) ); return 0; /* Assume an indexed expression can always yield a NULL */ } } /* ** Return true if the DISTINCT expression-list passed as the third argument ** is redundant. ** ** A DISTINCT list is redundant if any subset of the columns in the ** DISTINCT list are collectively unique and individually non-null. */ static int isDistinctRedundant( Parse *pParse, /* Parsing context */ SrcList *pTabList, /* The FROM clause */ WhereClause *pWC, /* The WHERE clause */ ExprList *pDistinct /* The result set that needs to be DISTINCT */ ){ Table *pTab; Index *pIdx; int i; int iBase; /* If there is more than one table or sub-select in the FROM clause of ** this query, then it will not be possible to show that the DISTINCT ** clause is redundant. */ if( pTabList->nSrc!=1 ) return 0; iBase = pTabList->a[0].iCursor; pTab = pTabList->a[0].pTab; /* If any of the expressions is an IPK column on table iBase, then return ** true. Note: The (p->iTable==iBase) part of this test may be false if the ** current SELECT is a correlated sub-query. */ for(i=0; inExpr; i++){ Expr *p = sqlite3ExprSkipCollateAndLikely(pDistinct->a[i].pExpr); if( NEVER(p==0) ) continue; if( p->op!=TK_COLUMN && p->op!=TK_AGG_COLUMN ) continue; if( p->iTable==iBase && p->iColumn<0 ) return 1; } /* Loop through all indices on the table, checking each to see if it makes ** the DISTINCT qualifier redundant. It does so if: ** ** 1. The index is itself UNIQUE, and ** ** 2. All of the columns in the index are either part of the pDistinct ** list, or else the WHERE clause contains a term of the form "col=X", ** where X is a constant value. The collation sequences of the ** comparison and select-list expressions must match those of the index. ** ** 3. All of those index columns for which the WHERE clause does not ** contain a "col=X" term are subject to a NOT NULL constraint. */ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ if( !IsUniqueIndex(pIdx) ) continue; if( pIdx->pPartIdxWhere ) continue; for(i=0; inKeyCol; i++){ if( 0==sqlite3WhereFindTerm(pWC, iBase, i, ~(Bitmask)0, WO_EQ, pIdx) ){ if( findIndexCol(pParse, pDistinct, iBase, pIdx, i)<0 ) break; if( indexColumnNotNull(pIdx, i)==0 ) break; } } if( i==pIdx->nKeyCol ){ /* This index implies that the DISTINCT qualifier is redundant. */ return 1; } } return 0; } /* ** Estimate the logarithm of the input value to base 2. */ static LogEst estLog(LogEst N){ return N<=10 ? 0 : sqlite3LogEst(N) - 33; } /* ** Convert OP_Column opcodes to OP_Copy in previously generated code. ** ** This routine runs over generated VDBE code and translates OP_Column ** opcodes into OP_Copy when the table is being accessed via co-routine ** instead of via table lookup. ** ** If the iAutoidxCur is not zero, then any OP_Rowid instructions on ** cursor iTabCur are transformed into OP_Sequence opcode for the ** iAutoidxCur cursor, in order to generate unique rowids for the ** automatic index being generated. */ static void translateColumnToCopy( Parse *pParse, /* Parsing context */ int iStart, /* Translate from this opcode to the end */ int iTabCur, /* OP_Column/OP_Rowid references to this table */ int iRegister, /* The first column is in this register */ int iAutoidxCur /* If non-zero, cursor of autoindex being generated */ ){ Vdbe *v = pParse->pVdbe; VdbeOp *pOp = sqlite3VdbeGetOp(v, iStart); int iEnd = sqlite3VdbeCurrentAddr(v); if( pParse->db->mallocFailed ) return; for(; iStartp1!=iTabCur ) continue; if( pOp->opcode==OP_Column ){ pOp->opcode = OP_Copy; pOp->p1 = pOp->p2 + iRegister; pOp->p2 = pOp->p3; pOp->p3 = 0; pOp->p5 = 2; /* Cause the MEM_Subtype flag to be cleared */ }else if( pOp->opcode==OP_Rowid ){ pOp->opcode = OP_Sequence; pOp->p1 = iAutoidxCur; #ifdef SQLITE_ALLOW_ROWID_IN_VIEW if( iAutoidxCur==0 ){ pOp->opcode = OP_Null; pOp->p3 = 0; } #endif } } } /* ** Two routines for printing the content of an sqlite3_index_info ** structure. Used for testing and debugging only. If neither ** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines ** are no-ops. */ #if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(WHERETRACE_ENABLED) static void whereTraceIndexInfoInputs(sqlite3_index_info *p){ int i; if( !sqlite3WhereTrace ) return; for(i=0; inConstraint; i++){ sqlite3DebugPrintf( " constraint[%d]: col=%d termid=%d op=%d usabled=%d collseq=%s\n", i, p->aConstraint[i].iColumn, p->aConstraint[i].iTermOffset, p->aConstraint[i].op, p->aConstraint[i].usable, sqlite3_vtab_collation(p,i)); } for(i=0; inOrderBy; i++){ sqlite3DebugPrintf(" orderby[%d]: col=%d desc=%d\n", i, p->aOrderBy[i].iColumn, p->aOrderBy[i].desc); } } static void whereTraceIndexInfoOutputs(sqlite3_index_info *p){ int i; if( !sqlite3WhereTrace ) return; for(i=0; inConstraint; i++){ sqlite3DebugPrintf(" usage[%d]: argvIdx=%d omit=%d\n", i, p->aConstraintUsage[i].argvIndex, p->aConstraintUsage[i].omit); } sqlite3DebugPrintf(" idxNum=%d\n", p->idxNum); sqlite3DebugPrintf(" idxStr=%s\n", p->idxStr); sqlite3DebugPrintf(" orderByConsumed=%d\n", p->orderByConsumed); sqlite3DebugPrintf(" estimatedCost=%g\n", p->estimatedCost); sqlite3DebugPrintf(" estimatedRows=%lld\n", p->estimatedRows); } #else #define whereTraceIndexInfoInputs(A) #define whereTraceIndexInfoOutputs(A) #endif /* ** We know that pSrc is an operand of an outer join. Return true if ** pTerm is a constraint that is compatible with that join. ** ** pTerm must be EP_OuterON if pSrc is the right operand of an ** outer join. pTerm can be either EP_OuterON or EP_InnerON if pSrc ** is the left operand of a RIGHT join. ** ** See https://sqlite.org/forum/forumpost/206d99a16dd9212f ** for an example of a WHERE clause constraints that may not be used on ** the right table of a RIGHT JOIN because the constraint implies a ** not-NULL condition on the left table of the RIGHT JOIN. */ static int constraintCompatibleWithOuterJoin( const WhereTerm *pTerm, /* WHERE clause term to check */ const SrcItem *pSrc /* Table we are trying to access */ ){ assert( (pSrc->fg.jointype&(JT_LEFT|JT_LTORJ|JT_RIGHT))!=0 ); /* By caller */ testcase( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))==JT_LEFT ); testcase( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))==JT_LTORJ ); testcase( ExprHasProperty(pTerm->pExpr, EP_OuterON) ) testcase( ExprHasProperty(pTerm->pExpr, EP_InnerON) ); if( !ExprHasProperty(pTerm->pExpr, EP_OuterON|EP_InnerON) || pTerm->pExpr->w.iJoin != pSrc->iCursor ){ return 0; } if( (pSrc->fg.jointype & (JT_LEFT|JT_RIGHT))!=0 && ExprHasProperty(pTerm->pExpr, EP_InnerON) ){ return 0; } return 1; } #ifndef SQLITE_OMIT_AUTOMATIC_INDEX /* ** Return TRUE if the WHERE clause term pTerm is of a form where it ** could be used with an index to access pSrc, assuming an appropriate ** index existed. */ static int termCanDriveIndex( const WhereTerm *pTerm, /* WHERE clause term to check */ const SrcItem *pSrc, /* Table we are trying to access */ const Bitmask notReady /* Tables in outer loops of the join */ ){ char aff; if( pTerm->leftCursor!=pSrc->iCursor ) return 0; if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) return 0; assert( (pSrc->fg.jointype & JT_RIGHT)==0 ); if( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0 && !constraintCompatibleWithOuterJoin(pTerm,pSrc) ){ return 0; /* See https://sqlite.org/forum/forumpost/51e6959f61 */ } if( (pTerm->prereqRight & notReady)!=0 ) return 0; assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); if( pTerm->u.x.leftColumn<0 ) return 0; aff = pSrc->pTab->aCol[pTerm->u.x.leftColumn].affinity; if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0; testcase( pTerm->pExpr->op==TK_IS ); return 1; } #endif #ifndef SQLITE_OMIT_AUTOMATIC_INDEX /* ** Generate code to construct the Index object for an automatic index ** and to set up the WhereLevel object pLevel so that the code generator ** makes use of the automatic index. */ static SQLITE_NOINLINE void constructAutomaticIndex( Parse *pParse, /* The parsing context */ const WhereClause *pWC, /* The WHERE clause */ const SrcItem *pSrc, /* The FROM clause term to get the next index */ const Bitmask notReady, /* Mask of cursors that are not available */ WhereLevel *pLevel /* Write new index here */ ){ int nKeyCol; /* Number of columns in the constructed index */ WhereTerm *pTerm; /* A single term of the WHERE clause */ WhereTerm *pWCEnd; /* End of pWC->a[] */ Index *pIdx; /* Object describing the transient index */ Vdbe *v; /* Prepared statement under construction */ int addrInit; /* Address of the initialization bypass jump */ Table *pTable; /* The table being indexed */ int addrTop; /* Top of the index fill loop */ int regRecord; /* Register holding an index record */ int n; /* Column counter */ int i; /* Loop counter */ int mxBitCol; /* Maximum column in pSrc->colUsed */ CollSeq *pColl; /* Collating sequence to on a column */ WhereLoop *pLoop; /* The Loop object */ char *zNotUsed; /* Extra space on the end of pIdx */ Bitmask idxCols; /* Bitmap of columns used for indexing */ Bitmask extraCols; /* Bitmap of additional columns */ u8 sentWarning = 0; /* True if a warnning has been issued */ Expr *pPartial = 0; /* Partial Index Expression */ int iContinue = 0; /* Jump here to skip excluded rows */ SrcItem *pTabItem; /* FROM clause term being indexed */ int addrCounter = 0; /* Address where integer counter is initialized */ int regBase; /* Array of registers where record is assembled */ /* Generate code to skip over the creation and initialization of the ** transient index on 2nd and subsequent iterations of the loop. */ v = pParse->pVdbe; assert( v!=0 ); addrInit = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v); /* Count the number of columns that will be added to the index ** and used to match WHERE clause constraints */ nKeyCol = 0; pTable = pSrc->pTab; pWCEnd = &pWC->a[pWC->nTerm]; pLoop = pLevel->pWLoop; idxCols = 0; for(pTerm=pWC->a; pTermpExpr; /* Make the automatic index a partial index if there are terms in the ** WHERE clause (or the ON clause of a LEFT join) that constrain which ** rows of the target table (pSrc) that can be used. */ if( (pTerm->wtFlags & TERM_VIRTUAL)==0 && sqlite3ExprIsTableConstraint(pExpr, pSrc) ){ pPartial = sqlite3ExprAnd(pParse, pPartial, sqlite3ExprDup(pParse->db, pExpr, 0)); } if( termCanDriveIndex(pTerm, pSrc, notReady) ){ int iCol; Bitmask cMask; assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); iCol = pTerm->u.x.leftColumn; cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol); testcase( iCol==BMS ); testcase( iCol==BMS-1 ); if( !sentWarning ){ sqlite3_log(SQLITE_WARNING_AUTOINDEX, "automatic index on %s(%s)", pTable->zName, pTable->aCol[iCol].zCnName); sentWarning = 1; } if( (idxCols & cMask)==0 ){ if( whereLoopResize(pParse->db, pLoop, nKeyCol+1) ){ goto end_auto_index_create; } pLoop->aLTerm[nKeyCol++] = pTerm; idxCols |= cMask; } } } assert( nKeyCol>0 || pParse->db->mallocFailed ); pLoop->u.btree.nEq = pLoop->nLTerm = nKeyCol; pLoop->wsFlags = WHERE_COLUMN_EQ | WHERE_IDX_ONLY | WHERE_INDEXED | WHERE_AUTO_INDEX; /* Count the number of additional columns needed to create a ** covering index. A "covering index" is an index that contains all ** columns that are needed by the query. With a covering index, the ** original table never needs to be accessed. Automatic indices must ** be a covering index because the index will not be updated if the ** original table changes and the index and table cannot both be used ** if they go out of sync. */ extraCols = pSrc->colUsed & (~idxCols | MASKBIT(BMS-1)); mxBitCol = MIN(BMS-1,pTable->nCol); testcase( pTable->nCol==BMS-1 ); testcase( pTable->nCol==BMS-2 ); for(i=0; icolUsed & MASKBIT(BMS-1) ){ nKeyCol += pTable->nCol - BMS + 1; } /* Construct the Index object to describe this index */ pIdx = sqlite3AllocateIndexObject(pParse->db, nKeyCol+1, 0, &zNotUsed); if( pIdx==0 ) goto end_auto_index_create; pLoop->u.btree.pIndex = pIdx; pIdx->zName = "auto-index"; pIdx->pTable = pTable; n = 0; idxCols = 0; for(pTerm=pWC->a; pTermeOperator & (WO_OR|WO_AND))==0 ); iCol = pTerm->u.x.leftColumn; cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol); testcase( iCol==BMS-1 ); testcase( iCol==BMS ); if( (idxCols & cMask)==0 ){ Expr *pX = pTerm->pExpr; idxCols |= cMask; pIdx->aiColumn[n] = pTerm->u.x.leftColumn; pColl = sqlite3ExprCompareCollSeq(pParse, pX); assert( pColl!=0 || pParse->nErr>0 ); /* TH3 collate01.800 */ pIdx->azColl[n] = pColl ? pColl->zName : sqlite3StrBINARY; n++; } } } assert( (u32)n==pLoop->u.btree.nEq ); /* Add additional columns needed to make the automatic index into ** a covering index */ for(i=0; iaiColumn[n] = i; pIdx->azColl[n] = sqlite3StrBINARY; n++; } } if( pSrc->colUsed & MASKBIT(BMS-1) ){ for(i=BMS-1; inCol; i++){ pIdx->aiColumn[n] = i; pIdx->azColl[n] = sqlite3StrBINARY; n++; } } assert( n==nKeyCol ); pIdx->aiColumn[n] = XN_ROWID; pIdx->azColl[n] = sqlite3StrBINARY; /* Create the automatic index */ assert( pLevel->iIdxCur>=0 ); pLevel->iIdxCur = pParse->nTab++; sqlite3VdbeAddOp2(v, OP_OpenAutoindex, pLevel->iIdxCur, nKeyCol+1); sqlite3VdbeSetP4KeyInfo(pParse, pIdx); VdbeComment((v, "for %s", pTable->zName)); if( OptimizationEnabled(pParse->db, SQLITE_BloomFilter) ){ pLevel->regFilter = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Blob, 10000, pLevel->regFilter); } /* Fill the automatic index with content */ pTabItem = &pWC->pWInfo->pTabList->a[pLevel->iFrom]; if( pTabItem->fg.viaCoroutine ){ int regYield = pTabItem->regReturn; addrCounter = sqlite3VdbeAddOp2(v, OP_Integer, 0, 0); sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub); addrTop = sqlite3VdbeAddOp1(v, OP_Yield, regYield); VdbeCoverage(v); VdbeComment((v, "next row of %s", pTabItem->pTab->zName)); }else{ addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur); VdbeCoverage(v); } if( pPartial ){ iContinue = sqlite3VdbeMakeLabel(pParse); sqlite3ExprIfFalse(pParse, pPartial, iContinue, SQLITE_JUMPIFNULL); pLoop->wsFlags |= WHERE_PARTIALIDX; } regRecord = sqlite3GetTempReg(pParse); regBase = sqlite3GenerateIndexKey( pParse, pIdx, pLevel->iTabCur, regRecord, 0, 0, 0, 0 ); if( pLevel->regFilter ){ sqlite3VdbeAddOp4Int(v, OP_FilterAdd, pLevel->regFilter, 0, regBase, pLoop->u.btree.nEq); } sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord); sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT); if( pPartial ) sqlite3VdbeResolveLabel(v, iContinue); if( pTabItem->fg.viaCoroutine ){ sqlite3VdbeChangeP2(v, addrCounter, regBase+n); testcase( pParse->db->mallocFailed ); assert( pLevel->iIdxCur>0 ); translateColumnToCopy(pParse, addrTop, pLevel->iTabCur, pTabItem->regResult, pLevel->iIdxCur); sqlite3VdbeGoto(v, addrTop); pTabItem->fg.viaCoroutine = 0; }else{ sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1); VdbeCoverage(v); sqlite3VdbeChangeP5(v, SQLITE_STMTSTATUS_AUTOINDEX); } sqlite3VdbeJumpHere(v, addrTop); sqlite3ReleaseTempReg(pParse, regRecord); /* Jump here when skipping the initialization */ sqlite3VdbeJumpHere(v, addrInit); end_auto_index_create: sqlite3ExprDelete(pParse->db, pPartial); } #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */ /* ** Generate bytecode that will initialize a Bloom filter that is appropriate ** for pLevel. ** ** If there are inner loops within pLevel that have the WHERE_BLOOMFILTER ** flag set, initialize a Bloomfilter for them as well. Except don't do ** this recursive initialization if the SQLITE_BloomPulldown optimization has ** been turned off. ** ** When the Bloom filter is initialized, the WHERE_BLOOMFILTER flag is cleared ** from the loop, but the regFilter value is set to a register that implements ** the Bloom filter. When regFilter is positive, the ** sqlite3WhereCodeOneLoopStart() will generate code to test the Bloom filter ** and skip the subsequence B-Tree seek if the Bloom filter indicates that ** no matching rows exist. ** ** This routine may only be called if it has previously been determined that ** the loop would benefit from a Bloom filter, and the WHERE_BLOOMFILTER bit ** is set. */ static SQLITE_NOINLINE void sqlite3ConstructBloomFilter( WhereInfo *pWInfo, /* The WHERE clause */ int iLevel, /* Index in pWInfo->a[] that is pLevel */ WhereLevel *pLevel, /* Make a Bloom filter for this FROM term */ Bitmask notReady /* Loops that are not ready */ ){ int addrOnce; /* Address of opening OP_Once */ int addrTop; /* Address of OP_Rewind */ int addrCont; /* Jump here to skip a row */ const WhereTerm *pTerm; /* For looping over WHERE clause terms */ const WhereTerm *pWCEnd; /* Last WHERE clause term */ Parse *pParse = pWInfo->pParse; /* Parsing context */ Vdbe *v = pParse->pVdbe; /* VDBE under construction */ WhereLoop *pLoop = pLevel->pWLoop; /* The loop being coded */ int iCur; /* Cursor for table getting the filter */ assert( pLoop!=0 ); assert( v!=0 ); assert( pLoop->wsFlags & WHERE_BLOOMFILTER ); addrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v); do{ const SrcItem *pItem; const Table *pTab; u64 sz; sqlite3WhereExplainBloomFilter(pParse, pWInfo, pLevel); addrCont = sqlite3VdbeMakeLabel(pParse); iCur = pLevel->iTabCur; pLevel->regFilter = ++pParse->nMem; /* The Bloom filter is a Blob held in a register. Initialize it ** to zero-filled blob of at least 80K bits, but maybe more if the ** estimated size of the table is larger. We could actually ** measure the size of the table at run-time using OP_Count with ** P3==1 and use that value to initialize the blob. But that makes ** testing complicated. By basing the blob size on the value in the ** sqlite_stat1 table, testing is much easier. */ pItem = &pWInfo->pTabList->a[pLevel->iFrom]; assert( pItem!=0 ); pTab = pItem->pTab; assert( pTab!=0 ); sz = sqlite3LogEstToInt(pTab->nRowLogEst); if( sz<10000 ){ sz = 10000; }else if( sz>10000000 ){ sz = 10000000; } sqlite3VdbeAddOp2(v, OP_Blob, (int)sz, pLevel->regFilter); addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, iCur); VdbeCoverage(v); pWCEnd = &pWInfo->sWC.a[pWInfo->sWC.nTerm]; for(pTerm=pWInfo->sWC.a; pTermpExpr; if( (pTerm->wtFlags & TERM_VIRTUAL)==0 && sqlite3ExprIsTableConstraint(pExpr, pItem) ){ sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL); } } if( pLoop->wsFlags & WHERE_IPK ){ int r1 = sqlite3GetTempReg(pParse); sqlite3VdbeAddOp2(v, OP_Rowid, iCur, r1); sqlite3VdbeAddOp4Int(v, OP_FilterAdd, pLevel->regFilter, 0, r1, 1); sqlite3ReleaseTempReg(pParse, r1); }else{ Index *pIdx = pLoop->u.btree.pIndex; int n = pLoop->u.btree.nEq; int r1 = sqlite3GetTempRange(pParse, n); int jj; for(jj=0; jjaiColumn[jj]; assert( pIdx->pTable==pItem->pTab ); sqlite3ExprCodeGetColumnOfTable(v, pIdx->pTable, iCur, iCol,r1+jj); } sqlite3VdbeAddOp4Int(v, OP_FilterAdd, pLevel->regFilter, 0, r1, n); sqlite3ReleaseTempRange(pParse, r1, n); } sqlite3VdbeResolveLabel(v, addrCont); sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1); VdbeCoverage(v); sqlite3VdbeJumpHere(v, addrTop); pLoop->wsFlags &= ~WHERE_BLOOMFILTER; if( OptimizationDisabled(pParse->db, SQLITE_BloomPulldown) ) break; while( ++iLevel < pWInfo->nLevel ){ const SrcItem *pTabItem; pLevel = &pWInfo->a[iLevel]; pTabItem = &pWInfo->pTabList->a[pLevel->iFrom]; if( pTabItem->fg.jointype & (JT_LEFT|JT_LTORJ) ) continue; pLoop = pLevel->pWLoop; if( NEVER(pLoop==0) ) continue; if( pLoop->prereq & notReady ) continue; if( (pLoop->wsFlags & (WHERE_BLOOMFILTER|WHERE_COLUMN_IN)) ==WHERE_BLOOMFILTER ){ /* This is a candidate for bloom-filter pull-down (early evaluation). ** The test that WHERE_COLUMN_IN is omitted is important, as we are ** not able to do early evaluation of bloom filters that make use of ** the IN operator */ break; } } }while( iLevel < pWInfo->nLevel ); sqlite3VdbeJumpHere(v, addrOnce); } #ifndef SQLITE_OMIT_VIRTUALTABLE /* ** Allocate and populate an sqlite3_index_info structure. It is the ** responsibility of the caller to eventually release the structure ** by passing the pointer returned by this function to freeIndexInfo(). */ static sqlite3_index_info *allocateIndexInfo( WhereInfo *pWInfo, /* The WHERE clause */ WhereClause *pWC, /* The WHERE clause being analyzed */ Bitmask mUnusable, /* Ignore terms with these prereqs */ SrcItem *pSrc, /* The FROM clause term that is the vtab */ u16 *pmNoOmit /* Mask of terms not to omit */ ){ int i, j; int nTerm; Parse *pParse = pWInfo->pParse; struct sqlite3_index_constraint *pIdxCons; struct sqlite3_index_orderby *pIdxOrderBy; struct sqlite3_index_constraint_usage *pUsage; struct HiddenIndexInfo *pHidden; WhereTerm *pTerm; int nOrderBy; sqlite3_index_info *pIdxInfo; u16 mNoOmit = 0; const Table *pTab; int eDistinct = 0; ExprList *pOrderBy = pWInfo->pOrderBy; assert( pSrc!=0 ); pTab = pSrc->pTab; assert( pTab!=0 ); assert( IsVirtual(pTab) ); /* Find all WHERE clause constraints referring to this virtual table. ** Mark each term with the TERM_OK flag. Set nTerm to the number of ** terms found. */ for(i=nTerm=0, pTerm=pWC->a; inTerm; i++, pTerm++){ pTerm->wtFlags &= ~TERM_OK; if( pTerm->leftCursor != pSrc->iCursor ) continue; if( pTerm->prereqRight & mUnusable ) continue; assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) ); testcase( pTerm->eOperator & WO_IN ); testcase( pTerm->eOperator & WO_ISNULL ); testcase( pTerm->eOperator & WO_IS ); testcase( pTerm->eOperator & WO_ALL ); if( (pTerm->eOperator & ~(WO_EQUIV))==0 ) continue; if( pTerm->wtFlags & TERM_VNULL ) continue; assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); assert( pTerm->u.x.leftColumn>=XN_ROWID ); assert( pTerm->u.x.leftColumnnCol ); if( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0 && !constraintCompatibleWithOuterJoin(pTerm,pSrc) ){ continue; } nTerm++; pTerm->wtFlags |= TERM_OK; } /* If the ORDER BY clause contains only columns in the current ** virtual table then allocate space for the aOrderBy part of ** the sqlite3_index_info structure. */ nOrderBy = 0; if( pOrderBy ){ int n = pOrderBy->nExpr; for(i=0; ia[i].pExpr; Expr *pE2; /* Skip over constant terms in the ORDER BY clause */ if( sqlite3ExprIsConstant(pExpr) ){ continue; } /* Virtual tables are unable to deal with NULLS FIRST */ if( pOrderBy->a[i].fg.sortFlags & KEYINFO_ORDER_BIGNULL ) break; /* First case - a direct column references without a COLLATE operator */ if( pExpr->op==TK_COLUMN && pExpr->iTable==pSrc->iCursor ){ assert( pExpr->iColumn>=XN_ROWID && pExpr->iColumnnCol ); continue; } /* 2nd case - a column reference with a COLLATE operator. Only match ** of the COLLATE operator matches the collation of the column. */ if( pExpr->op==TK_COLLATE && (pE2 = pExpr->pLeft)->op==TK_COLUMN && pE2->iTable==pSrc->iCursor ){ const char *zColl; /* The collating sequence name */ assert( !ExprHasProperty(pExpr, EP_IntValue) ); assert( pExpr->u.zToken!=0 ); assert( pE2->iColumn>=XN_ROWID && pE2->iColumnnCol ); pExpr->iColumn = pE2->iColumn; if( pE2->iColumn<0 ) continue; /* Collseq does not matter for rowid */ zColl = sqlite3ColumnColl(&pTab->aCol[pE2->iColumn]); if( zColl==0 ) zColl = sqlite3StrBINARY; if( sqlite3_stricmp(pExpr->u.zToken, zColl)==0 ) continue; } /* No matches cause a break out of the loop */ break; } if( i==n ){ nOrderBy = n; if( (pWInfo->wctrlFlags & WHERE_DISTINCTBY) ){ eDistinct = 2 + ((pWInfo->wctrlFlags & WHERE_SORTBYGROUP)!=0); }else if( pWInfo->wctrlFlags & WHERE_GROUPBY ){ eDistinct = 1; } } } /* Allocate the sqlite3_index_info structure */ pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo) + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm + sizeof(*pIdxOrderBy)*nOrderBy + sizeof(*pHidden) + sizeof(sqlite3_value*)*nTerm ); if( pIdxInfo==0 ){ sqlite3ErrorMsg(pParse, "out of memory"); return 0; } pHidden = (struct HiddenIndexInfo*)&pIdxInfo[1]; pIdxCons = (struct sqlite3_index_constraint*)&pHidden->aRhs[nTerm]; pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm]; pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy]; pIdxInfo->aConstraint = pIdxCons; pIdxInfo->aOrderBy = pIdxOrderBy; pIdxInfo->aConstraintUsage = pUsage; pHidden->pWC = pWC; pHidden->pParse = pParse; pHidden->eDistinct = eDistinct; pHidden->mIn = 0; for(i=j=0, pTerm=pWC->a; inTerm; i++, pTerm++){ u16 op; if( (pTerm->wtFlags & TERM_OK)==0 ) continue; pIdxCons[j].iColumn = pTerm->u.x.leftColumn; pIdxCons[j].iTermOffset = i; op = pTerm->eOperator & WO_ALL; if( op==WO_IN ){ if( (pTerm->wtFlags & TERM_SLICE)==0 ){ pHidden->mIn |= SMASKBIT32(j); } op = WO_EQ; } if( op==WO_AUX ){ pIdxCons[j].op = pTerm->eMatchOp; }else if( op & (WO_ISNULL|WO_IS) ){ if( op==WO_ISNULL ){ pIdxCons[j].op = SQLITE_INDEX_CONSTRAINT_ISNULL; }else{ pIdxCons[j].op = SQLITE_INDEX_CONSTRAINT_IS; } }else{ pIdxCons[j].op = (u8)op; /* The direct assignment in the previous line is possible only because ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical. The ** following asserts verify this fact. */ assert( WO_EQ==SQLITE_INDEX_CONSTRAINT_EQ ); assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT ); assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE ); assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT ); assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE ); assert( pTerm->eOperator&(WO_IN|WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_AUX) ); if( op & (WO_LT|WO_LE|WO_GT|WO_GE) && sqlite3ExprIsVector(pTerm->pExpr->pRight) ){ testcase( j!=i ); if( j<16 ) mNoOmit |= (1 << j); if( op==WO_LT ) pIdxCons[j].op = WO_LE; if( op==WO_GT ) pIdxCons[j].op = WO_GE; } } j++; } assert( j==nTerm ); pIdxInfo->nConstraint = j; for(i=j=0; ia[i].pExpr; if( sqlite3ExprIsConstant(pExpr) ) continue; assert( pExpr->op==TK_COLUMN || (pExpr->op==TK_COLLATE && pExpr->pLeft->op==TK_COLUMN && pExpr->iColumn==pExpr->pLeft->iColumn) ); pIdxOrderBy[j].iColumn = pExpr->iColumn; pIdxOrderBy[j].desc = pOrderBy->a[i].fg.sortFlags & KEYINFO_ORDER_DESC; j++; } pIdxInfo->nOrderBy = j; *pmNoOmit = mNoOmit; return pIdxInfo; } /* ** Free an sqlite3_index_info structure allocated by allocateIndexInfo() ** and possibly modified by xBestIndex methods. */ static void freeIndexInfo(sqlite3 *db, sqlite3_index_info *pIdxInfo){ HiddenIndexInfo *pHidden; int i; assert( pIdxInfo!=0 ); pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; assert( pHidden->pParse!=0 ); assert( pHidden->pParse->db==db ); for(i=0; inConstraint; i++){ sqlite3ValueFree(pHidden->aRhs[i]); /* IMP: R-14553-25174 */ pHidden->aRhs[i] = 0; } sqlite3DbFree(db, pIdxInfo); } /* ** The table object reference passed as the second argument to this function ** must represent a virtual table. This function invokes the xBestIndex() ** method of the virtual table with the sqlite3_index_info object that ** comes in as the 3rd argument to this function. ** ** If an error occurs, pParse is populated with an error message and an ** appropriate error code is returned. A return of SQLITE_CONSTRAINT from ** xBestIndex is not considered an error. SQLITE_CONSTRAINT indicates that ** the current configuration of "unusable" flags in sqlite3_index_info can ** not result in a valid plan. ** ** Whether or not an error is returned, it is the responsibility of the ** caller to eventually free p->idxStr if p->needToFreeIdxStr indicates ** that this is required. */ static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){ sqlite3_vtab *pVtab = sqlite3GetVTable(pParse->db, pTab)->pVtab; int rc; whereTraceIndexInfoInputs(p); pParse->db->nSchemaLock++; rc = pVtab->pModule->xBestIndex(pVtab, p); pParse->db->nSchemaLock--; whereTraceIndexInfoOutputs(p); if( rc!=SQLITE_OK && rc!=SQLITE_CONSTRAINT ){ if( rc==SQLITE_NOMEM ){ sqlite3OomFault(pParse->db); }else if( !pVtab->zErrMsg ){ sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc)); }else{ sqlite3ErrorMsg(pParse, "%s", pVtab->zErrMsg); } } sqlite3_free(pVtab->zErrMsg); pVtab->zErrMsg = 0; return rc; } #endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */ #ifdef SQLITE_ENABLE_STAT4 /* ** Estimate the location of a particular key among all keys in an ** index. Store the results in aStat as follows: ** ** aStat[0] Est. number of rows less than pRec ** aStat[1] Est. number of rows equal to pRec ** ** Return the index of the sample that is the smallest sample that ** is greater than or equal to pRec. Note that this index is not an index ** into the aSample[] array - it is an index into a virtual set of samples ** based on the contents of aSample[] and the number of fields in record ** pRec. */ static int whereKeyStats( Parse *pParse, /* Database connection */ Index *pIdx, /* Index to consider domain of */ UnpackedRecord *pRec, /* Vector of values to consider */ int roundUp, /* Round up if true. Round down if false */ tRowcnt *aStat /* OUT: stats written here */ ){ IndexSample *aSample = pIdx->aSample; int iCol; /* Index of required stats in anEq[] etc. */ int i; /* Index of first sample >= pRec */ int iSample; /* Smallest sample larger than or equal to pRec */ int iMin = 0; /* Smallest sample not yet tested */ int iTest; /* Next sample to test */ int res; /* Result of comparison operation */ int nField; /* Number of fields in pRec */ tRowcnt iLower = 0; /* anLt[] + anEq[] of largest sample pRec is > */ #ifndef SQLITE_DEBUG UNUSED_PARAMETER( pParse ); #endif assert( pRec!=0 ); assert( pIdx->nSample>0 ); assert( pRec->nField>0 ); /* Do a binary search to find the first sample greater than or equal ** to pRec. If pRec contains a single field, the set of samples to search ** is simply the aSample[] array. If the samples in aSample[] contain more ** than one fields, all fields following the first are ignored. ** ** If pRec contains N fields, where N is more than one, then as well as the ** samples in aSample[] (truncated to N fields), the search also has to ** consider prefixes of those samples. For example, if the set of samples ** in aSample is: ** ** aSample[0] = (a, 5) ** aSample[1] = (a, 10) ** aSample[2] = (b, 5) ** aSample[3] = (c, 100) ** aSample[4] = (c, 105) ** ** Then the search space should ideally be the samples above and the ** unique prefixes [a], [b] and [c]. But since that is hard to organize, ** the code actually searches this set: ** ** 0: (a) ** 1: (a, 5) ** 2: (a, 10) ** 3: (a, 10) ** 4: (b) ** 5: (b, 5) ** 6: (c) ** 7: (c, 100) ** 8: (c, 105) ** 9: (c, 105) ** ** For each sample in the aSample[] array, N samples are present in the ** effective sample array. In the above, samples 0 and 1 are based on ** sample aSample[0]. Samples 2 and 3 on aSample[1] etc. ** ** Often, sample i of each block of N effective samples has (i+1) fields. ** Except, each sample may be extended to ensure that it is greater than or ** equal to the previous sample in the array. For example, in the above, ** sample 2 is the first sample of a block of N samples, so at first it ** appears that it should be 1 field in size. However, that would make it ** smaller than sample 1, so the binary search would not work. As a result, ** it is extended to two fields. The duplicates that this creates do not ** cause any problems. */ nField = MIN(pRec->nField, pIdx->nSample); iCol = 0; iSample = pIdx->nSample * nField; do{ int iSamp; /* Index in aSample[] of test sample */ int n; /* Number of fields in test sample */ iTest = (iMin+iSample)/2; iSamp = iTest / nField; if( iSamp>0 ){ /* The proposed effective sample is a prefix of sample aSample[iSamp]. ** Specifically, the shortest prefix of at least (1 + iTest%nField) ** fields that is greater than the previous effective sample. */ for(n=(iTest % nField) + 1; nnField = n; res = sqlite3VdbeRecordCompare(aSample[iSamp].n, aSample[iSamp].p, pRec); if( res<0 ){ iLower = aSample[iSamp].anLt[n-1] + aSample[iSamp].anEq[n-1]; iMin = iTest+1; }else if( res==0 && ndb->mallocFailed==0 ){ if( res==0 ){ /* If (res==0) is true, then pRec must be equal to sample i. */ assert( inSample ); assert( iCol==nField-1 ); pRec->nField = nField; assert( 0==sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec) || pParse->db->mallocFailed ); }else{ /* Unless i==pIdx->nSample, indicating that pRec is larger than ** all samples in the aSample[] array, pRec must be smaller than the ** (iCol+1) field prefix of sample i. */ assert( i<=pIdx->nSample && i>=0 ); pRec->nField = iCol+1; assert( i==pIdx->nSample || sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)>0 || pParse->db->mallocFailed ); /* if i==0 and iCol==0, then record pRec is smaller than all samples ** in the aSample[] array. Otherwise, if (iCol>0) then pRec must ** be greater than or equal to the (iCol) field prefix of sample i. ** If (i>0), then pRec must also be greater than sample (i-1). */ if( iCol>0 ){ pRec->nField = iCol; assert( sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)<=0 || pParse->db->mallocFailed ); } if( i>0 ){ pRec->nField = nField; assert( sqlite3VdbeRecordCompare(aSample[i-1].n, aSample[i-1].p, pRec)<0 || pParse->db->mallocFailed ); } } } #endif /* ifdef SQLITE_DEBUG */ if( res==0 ){ /* Record pRec is equal to sample i */ assert( iCol==nField-1 ); aStat[0] = aSample[i].anLt[iCol]; aStat[1] = aSample[i].anEq[iCol]; }else{ /* At this point, the (iCol+1) field prefix of aSample[i] is the first ** sample that is greater than pRec. Or, if i==pIdx->nSample then pRec ** is larger than all samples in the array. */ tRowcnt iUpper, iGap; if( i>=pIdx->nSample ){ iUpper = pIdx->nRowEst0; }else{ iUpper = aSample[i].anLt[iCol]; } if( iLower>=iUpper ){ iGap = 0; }else{ iGap = iUpper - iLower; } if( roundUp ){ iGap = (iGap*2)/3; }else{ iGap = iGap/3; } aStat[0] = iLower + iGap; aStat[1] = pIdx->aAvgEq[nField-1]; } /* Restore the pRec->nField value before returning. */ pRec->nField = nField; return i; } #endif /* SQLITE_ENABLE_STAT4 */ /* ** If it is not NULL, pTerm is a term that provides an upper or lower ** bound on a range scan. Without considering pTerm, it is estimated ** that the scan will visit nNew rows. This function returns the number ** estimated to be visited after taking pTerm into account. ** ** If the user explicitly specified a likelihood() value for this term, ** then the return value is the likelihood multiplied by the number of ** input rows. Otherwise, this function assumes that an "IS NOT NULL" term ** has a likelihood of 0.50, and any other term a likelihood of 0.25. */ static LogEst whereRangeAdjust(WhereTerm *pTerm, LogEst nNew){ LogEst nRet = nNew; if( pTerm ){ if( pTerm->truthProb<=0 ){ nRet += pTerm->truthProb; }else if( (pTerm->wtFlags & TERM_VNULL)==0 ){ nRet -= 20; assert( 20==sqlite3LogEst(4) ); } } return nRet; } #ifdef SQLITE_ENABLE_STAT4 /* ** Return the affinity for a single column of an index. */ char sqlite3IndexColumnAffinity(sqlite3 *db, Index *pIdx, int iCol){ assert( iCol>=0 && iColnColumn ); if( !pIdx->zColAff ){ if( sqlite3IndexAffinityStr(db, pIdx)==0 ) return SQLITE_AFF_BLOB; } assert( pIdx->zColAff[iCol]!=0 ); return pIdx->zColAff[iCol]; } #endif #ifdef SQLITE_ENABLE_STAT4 /* ** This function is called to estimate the number of rows visited by a ** range-scan on a skip-scan index. For example: ** ** CREATE INDEX i1 ON t1(a, b, c); ** SELECT * FROM t1 WHERE a=? AND c BETWEEN ? AND ?; ** ** Value pLoop->nOut is currently set to the estimated number of rows ** visited for scanning (a=? AND b=?). This function reduces that estimate ** by some factor to account for the (c BETWEEN ? AND ?) expression based ** on the stat4 data for the index. this scan will be peformed multiple ** times (once for each (a,b) combination that matches a=?) is dealt with ** by the caller. ** ** It does this by scanning through all stat4 samples, comparing values ** extracted from pLower and pUpper with the corresponding column in each ** sample. If L and U are the number of samples found to be less than or ** equal to the values extracted from pLower and pUpper respectively, and ** N is the total number of samples, the pLoop->nOut value is adjusted ** as follows: ** ** nOut = nOut * ( min(U - L, 1) / N ) ** ** If pLower is NULL, or a value cannot be extracted from the term, L is ** set to zero. If pUpper is NULL, or a value cannot be extracted from it, ** U is set to N. ** ** Normally, this function sets *pbDone to 1 before returning. However, ** if no value can be extracted from either pLower or pUpper (and so the ** estimate of the number of rows delivered remains unchanged), *pbDone ** is left as is. ** ** If an error occurs, an SQLite error code is returned. Otherwise, ** SQLITE_OK. */ static int whereRangeSkipScanEst( Parse *pParse, /* Parsing & code generating context */ WhereTerm *pLower, /* Lower bound on the range. ex: "x>123" Might be NULL */ WhereTerm *pUpper, /* Upper bound on the range. ex: "x<455" Might be NULL */ WhereLoop *pLoop, /* Update the .nOut value of this loop */ int *pbDone /* Set to true if at least one expr. value extracted */ ){ Index *p = pLoop->u.btree.pIndex; int nEq = pLoop->u.btree.nEq; sqlite3 *db = pParse->db; int nLower = -1; int nUpper = p->nSample+1; int rc = SQLITE_OK; u8 aff = sqlite3IndexColumnAffinity(db, p, nEq); CollSeq *pColl; sqlite3_value *p1 = 0; /* Value extracted from pLower */ sqlite3_value *p2 = 0; /* Value extracted from pUpper */ sqlite3_value *pVal = 0; /* Value extracted from record */ pColl = sqlite3LocateCollSeq(pParse, p->azColl[nEq]); if( pLower ){ rc = sqlite3Stat4ValueFromExpr(pParse, pLower->pExpr->pRight, aff, &p1); nLower = 0; } if( pUpper && rc==SQLITE_OK ){ rc = sqlite3Stat4ValueFromExpr(pParse, pUpper->pExpr->pRight, aff, &p2); nUpper = p2 ? 0 : p->nSample; } if( p1 || p2 ){ int i; int nDiff; for(i=0; rc==SQLITE_OK && inSample; i++){ rc = sqlite3Stat4Column(db, p->aSample[i].p, p->aSample[i].n, nEq, &pVal); if( rc==SQLITE_OK && p1 ){ int res = sqlite3MemCompare(p1, pVal, pColl); if( res>=0 ) nLower++; } if( rc==SQLITE_OK && p2 ){ int res = sqlite3MemCompare(p2, pVal, pColl); if( res>=0 ) nUpper++; } } nDiff = (nUpper - nLower); if( nDiff<=0 ) nDiff = 1; /* If there is both an upper and lower bound specified, and the ** comparisons indicate that they are close together, use the fallback ** method (assume that the scan visits 1/64 of the rows) for estimating ** the number of rows visited. Otherwise, estimate the number of rows ** using the method described in the header comment for this function. */ if( nDiff!=1 || pUpper==0 || pLower==0 ){ int nAdjust = (sqlite3LogEst(p->nSample) - sqlite3LogEst(nDiff)); pLoop->nOut -= nAdjust; *pbDone = 1; WHERETRACE(0x10, ("range skip-scan regions: %u..%u adjust=%d est=%d\n", nLower, nUpper, nAdjust*-1, pLoop->nOut)); } }else{ assert( *pbDone==0 ); } sqlite3ValueFree(p1); sqlite3ValueFree(p2); sqlite3ValueFree(pVal); return rc; } #endif /* SQLITE_ENABLE_STAT4 */ /* ** This function is used to estimate the number of rows that will be visited ** by scanning an index for a range of values. The range may have an upper ** bound, a lower bound, or both. The WHERE clause terms that set the upper ** and lower bounds are represented by pLower and pUpper respectively. For ** example, assuming that index p is on t1(a): ** ** ... FROM t1 WHERE a > ? AND a < ? ... ** |_____| |_____| ** | | ** pLower pUpper ** ** If either of the upper or lower bound is not present, then NULL is passed in ** place of the corresponding WhereTerm. ** ** The value in (pBuilder->pNew->u.btree.nEq) is the number of the index ** column subject to the range constraint. Or, equivalently, the number of ** equality constraints optimized by the proposed index scan. For example, ** assuming index p is on t1(a, b), and the SQL query is: ** ** ... FROM t1 WHERE a = ? AND b > ? AND b < ? ... ** ** then nEq is set to 1 (as the range restricted column, b, is the second ** left-most column of the index). Or, if the query is: ** ** ... FROM t1 WHERE a > ? AND a < ? ... ** ** then nEq is set to 0. ** ** When this function is called, *pnOut is set to the sqlite3LogEst() of the ** number of rows that the index scan is expected to visit without ** considering the range constraints. If nEq is 0, then *pnOut is the number of ** rows in the index. Assuming no error occurs, *pnOut is adjusted (reduced) ** to account for the range constraints pLower and pUpper. ** ** In the absence of sqlite_stat4 ANALYZE data, or if such data cannot be ** used, a single range inequality reduces the search space by a factor of 4. ** and a pair of constraints (x>? AND x123" Might be NULL */ WhereTerm *pUpper, /* Upper bound on the range. ex: "x<455" Might be NULL */ WhereLoop *pLoop /* Modify the .nOut and maybe .rRun fields */ ){ int rc = SQLITE_OK; int nOut = pLoop->nOut; LogEst nNew; #ifdef SQLITE_ENABLE_STAT4 Index *p = pLoop->u.btree.pIndex; int nEq = pLoop->u.btree.nEq; if( p->nSample>0 && ALWAYS(nEqnSampleCol) && OptimizationEnabled(pParse->db, SQLITE_Stat4) ){ if( nEq==pBuilder->nRecValid ){ UnpackedRecord *pRec = pBuilder->pRec; tRowcnt a[2]; int nBtm = pLoop->u.btree.nBtm; int nTop = pLoop->u.btree.nTop; /* Variable iLower will be set to the estimate of the number of rows in ** the index that are less than the lower bound of the range query. The ** lower bound being the concatenation of $P and $L, where $P is the ** key-prefix formed by the nEq values matched against the nEq left-most ** columns of the index, and $L is the value in pLower. ** ** Or, if pLower is NULL or $L cannot be extracted from it (because it ** is not a simple variable or literal value), the lower bound of the ** range is $P. Due to a quirk in the way whereKeyStats() works, even ** if $L is available, whereKeyStats() is called for both ($P) and ** ($P:$L) and the larger of the two returned values is used. ** ** Similarly, iUpper is to be set to the estimate of the number of rows ** less than the upper bound of the range query. Where the upper bound ** is either ($P) or ($P:$U). Again, even if $U is available, both values ** of iUpper are requested of whereKeyStats() and the smaller used. ** ** The number of rows between the two bounds is then just iUpper-iLower. */ tRowcnt iLower; /* Rows less than the lower bound */ tRowcnt iUpper; /* Rows less than the upper bound */ int iLwrIdx = -2; /* aSample[] for the lower bound */ int iUprIdx = -1; /* aSample[] for the upper bound */ if( pRec ){ testcase( pRec->nField!=pBuilder->nRecValid ); pRec->nField = pBuilder->nRecValid; } /* Determine iLower and iUpper using ($P) only. */ if( nEq==0 ){ iLower = 0; iUpper = p->nRowEst0; }else{ /* Note: this call could be optimized away - since the same values must ** have been requested when testing key $P in whereEqualScanEst(). */ whereKeyStats(pParse, p, pRec, 0, a); iLower = a[0]; iUpper = a[0] + a[1]; } assert( pLower==0 || (pLower->eOperator & (WO_GT|WO_GE))!=0 ); assert( pUpper==0 || (pUpper->eOperator & (WO_LT|WO_LE))!=0 ); assert( p->aSortOrder!=0 ); if( p->aSortOrder[nEq] ){ /* The roles of pLower and pUpper are swapped for a DESC index */ SWAP(WhereTerm*, pLower, pUpper); SWAP(int, nBtm, nTop); } /* If possible, improve on the iLower estimate using ($P:$L). */ if( pLower ){ int n; /* Values extracted from pExpr */ Expr *pExpr = pLower->pExpr->pRight; rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, nBtm, nEq, &n); if( rc==SQLITE_OK && n ){ tRowcnt iNew; u16 mask = WO_GT|WO_LE; if( sqlite3ExprVectorSize(pExpr)>n ) mask = (WO_LE|WO_LT); iLwrIdx = whereKeyStats(pParse, p, pRec, 0, a); iNew = a[0] + ((pLower->eOperator & mask) ? a[1] : 0); if( iNew>iLower ) iLower = iNew; nOut--; pLower = 0; } } /* If possible, improve on the iUpper estimate using ($P:$U). */ if( pUpper ){ int n; /* Values extracted from pExpr */ Expr *pExpr = pUpper->pExpr->pRight; rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, nTop, nEq, &n); if( rc==SQLITE_OK && n ){ tRowcnt iNew; u16 mask = WO_GT|WO_LE; if( sqlite3ExprVectorSize(pExpr)>n ) mask = (WO_LE|WO_LT); iUprIdx = whereKeyStats(pParse, p, pRec, 1, a); iNew = a[0] + ((pUpper->eOperator & mask) ? a[1] : 0); if( iNewpRec = pRec; if( rc==SQLITE_OK ){ if( iUpper>iLower ){ nNew = sqlite3LogEst(iUpper - iLower); /* TUNING: If both iUpper and iLower are derived from the same ** sample, then assume they are 4x more selective. This brings ** the estimated selectivity more in line with what it would be ** if estimated without the use of STAT4 tables. */ if( iLwrIdx==iUprIdx ) nNew -= 20; assert( 20==sqlite3LogEst(4) ); }else{ nNew = 10; assert( 10==sqlite3LogEst(2) ); } if( nNewwtFlags & TERM_VNULL)==0 ); nNew = whereRangeAdjust(pLower, nOut); nNew = whereRangeAdjust(pUpper, nNew); /* TUNING: If there is both an upper and lower limit and neither limit ** has an application-defined likelihood(), assume the range is ** reduced by an additional 75%. This means that, by default, an open-ended ** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the ** index. While a closed range (e.g. col BETWEEN ? AND ?) is estimated to ** match 1/64 of the index. */ if( pLower && pLower->truthProb>0 && pUpper && pUpper->truthProb>0 ){ nNew -= 20; } nOut -= (pLower!=0) + (pUpper!=0); if( nNew<10 ) nNew = 10; if( nNewnOut>nOut ){ WHERETRACE(0x10,("Range scan lowers nOut from %d to %d\n", pLoop->nOut, nOut)); } #endif pLoop->nOut = (LogEst)nOut; return rc; } #ifdef SQLITE_ENABLE_STAT4 /* ** Estimate the number of rows that will be returned based on ** an equality constraint x=VALUE and where that VALUE occurs in ** the histogram data. This only works when x is the left-most ** column of an index and sqlite_stat4 histogram data is available ** for that index. When pExpr==NULL that means the constraint is ** "x IS NULL" instead of "x=VALUE". ** ** Write the estimated row count into *pnRow and return SQLITE_OK. ** If unable to make an estimate, leave *pnRow unchanged and return ** non-zero. ** ** This routine can fail if it is unable to load a collating sequence ** required for string comparison, or if unable to allocate memory ** for a UTF conversion required for comparison. The error is stored ** in the pParse structure. */ static int whereEqualScanEst( Parse *pParse, /* Parsing & code generating context */ WhereLoopBuilder *pBuilder, Expr *pExpr, /* Expression for VALUE in the x=VALUE constraint */ tRowcnt *pnRow /* Write the revised row estimate here */ ){ Index *p = pBuilder->pNew->u.btree.pIndex; int nEq = pBuilder->pNew->u.btree.nEq; UnpackedRecord *pRec = pBuilder->pRec; int rc; /* Subfunction return code */ tRowcnt a[2]; /* Statistics */ int bOk; assert( nEq>=1 ); assert( nEq<=p->nColumn ); assert( p->aSample!=0 ); assert( p->nSample>0 ); assert( pBuilder->nRecValidnRecValid<(nEq-1) ){ return SQLITE_NOTFOUND; } /* This is an optimization only. The call to sqlite3Stat4ProbeSetValue() ** below would return the same value. */ if( nEq>=p->nColumn ){ *pnRow = 1; return SQLITE_OK; } rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, 1, nEq-1, &bOk); pBuilder->pRec = pRec; if( rc!=SQLITE_OK ) return rc; if( bOk==0 ) return SQLITE_NOTFOUND; pBuilder->nRecValid = nEq; whereKeyStats(pParse, p, pRec, 0, a); WHERETRACE(0x10,("equality scan regions %s(%d): %d\n", p->zName, nEq-1, (int)a[1])); *pnRow = a[1]; return rc; } #endif /* SQLITE_ENABLE_STAT4 */ #ifdef SQLITE_ENABLE_STAT4 /* ** Estimate the number of rows that will be returned based on ** an IN constraint where the right-hand side of the IN operator ** is a list of values. Example: ** ** WHERE x IN (1,2,3,4) ** ** Write the estimated row count into *pnRow and return SQLITE_OK. ** If unable to make an estimate, leave *pnRow unchanged and return ** non-zero. ** ** This routine can fail if it is unable to load a collating sequence ** required for string comparison, or if unable to allocate memory ** for a UTF conversion required for comparison. The error is stored ** in the pParse structure. */ static int whereInScanEst( Parse *pParse, /* Parsing & code generating context */ WhereLoopBuilder *pBuilder, ExprList *pList, /* The value list on the RHS of "x IN (v1,v2,v3,...)" */ tRowcnt *pnRow /* Write the revised row estimate here */ ){ Index *p = pBuilder->pNew->u.btree.pIndex; i64 nRow0 = sqlite3LogEstToInt(p->aiRowLogEst[0]); int nRecValid = pBuilder->nRecValid; int rc = SQLITE_OK; /* Subfunction return code */ tRowcnt nEst; /* Number of rows for a single term */ tRowcnt nRowEst = 0; /* New estimate of the number of rows */ int i; /* Loop counter */ assert( p->aSample!=0 ); for(i=0; rc==SQLITE_OK && inExpr; i++){ nEst = nRow0; rc = whereEqualScanEst(pParse, pBuilder, pList->a[i].pExpr, &nEst); nRowEst += nEst; pBuilder->nRecValid = nRecValid; } if( rc==SQLITE_OK ){ if( nRowEst > nRow0 ) nRowEst = nRow0; *pnRow = nRowEst; WHERETRACE(0x10,("IN row estimate: est=%d\n", nRowEst)); } assert( pBuilder->nRecValid==nRecValid ); return rc; } #endif /* SQLITE_ENABLE_STAT4 */ #ifdef WHERETRACE_ENABLED /* ** Print the content of a WhereTerm object */ void sqlite3WhereTermPrint(WhereTerm *pTerm, int iTerm){ if( pTerm==0 ){ sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm); }else{ char zType[8]; char zLeft[50]; memcpy(zType, "....", 5); if( pTerm->wtFlags & TERM_VIRTUAL ) zType[0] = 'V'; if( pTerm->eOperator & WO_EQUIV ) zType[1] = 'E'; if( ExprHasProperty(pTerm->pExpr, EP_OuterON) ) zType[2] = 'L'; if( pTerm->wtFlags & TERM_CODED ) zType[3] = 'C'; if( pTerm->eOperator & WO_SINGLE ){ assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); sqlite3_snprintf(sizeof(zLeft),zLeft,"left={%d:%d}", pTerm->leftCursor, pTerm->u.x.leftColumn); }else if( (pTerm->eOperator & WO_OR)!=0 && pTerm->u.pOrInfo!=0 ){ sqlite3_snprintf(sizeof(zLeft),zLeft,"indexable=0x%llx", pTerm->u.pOrInfo->indexable); }else{ sqlite3_snprintf(sizeof(zLeft),zLeft,"left=%d", pTerm->leftCursor); } sqlite3DebugPrintf( "TERM-%-3d %p %s %-12s op=%03x wtFlags=%04x", iTerm, pTerm, zType, zLeft, pTerm->eOperator, pTerm->wtFlags); /* The 0x10000 .wheretrace flag causes extra information to be ** shown about each Term */ if( sqlite3WhereTrace & 0x10000 ){ sqlite3DebugPrintf(" prob=%-3d prereq=%llx,%llx", pTerm->truthProb, (u64)pTerm->prereqAll, (u64)pTerm->prereqRight); } if( (pTerm->eOperator & (WO_OR|WO_AND))==0 && pTerm->u.x.iField ){ sqlite3DebugPrintf(" iField=%d", pTerm->u.x.iField); } if( pTerm->iParent>=0 ){ sqlite3DebugPrintf(" iParent=%d", pTerm->iParent); } sqlite3DebugPrintf("\n"); sqlite3TreeViewExpr(0, pTerm->pExpr, 0); } } #endif #ifdef WHERETRACE_ENABLED /* ** Show the complete content of a WhereClause */ void sqlite3WhereClausePrint(WhereClause *pWC){ int i; for(i=0; inTerm; i++){ sqlite3WhereTermPrint(&pWC->a[i], i); } } #endif #ifdef WHERETRACE_ENABLED /* ** Print a WhereLoop object for debugging purposes */ void sqlite3WhereLoopPrint(WhereLoop *p, WhereClause *pWC){ WhereInfo *pWInfo = pWC->pWInfo; int nb = 1+(pWInfo->pTabList->nSrc+3)/4; SrcItem *pItem = pWInfo->pTabList->a + p->iTab; Table *pTab = pItem->pTab; Bitmask mAll = (((Bitmask)1)<<(nb*4)) - 1; sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p->cId, p->iTab, nb, p->maskSelf, nb, p->prereq & mAll); sqlite3DebugPrintf(" %12s", pItem->zAlias ? pItem->zAlias : pTab->zName); if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){ const char *zName; if( p->u.btree.pIndex && (zName = p->u.btree.pIndex->zName)!=0 ){ if( strncmp(zName, "sqlite_autoindex_", 17)==0 ){ int i = sqlite3Strlen30(zName) - 1; while( zName[i]!='_' ) i--; zName += i; } sqlite3DebugPrintf(".%-16s %2d", zName, p->u.btree.nEq); }else{ sqlite3DebugPrintf("%20s",""); } }else{ char *z; if( p->u.vtab.idxStr ){ z = sqlite3_mprintf("(%d,\"%s\",%#x)", p->u.vtab.idxNum, p->u.vtab.idxStr, p->u.vtab.omitMask); }else{ z = sqlite3_mprintf("(%d,%x)", p->u.vtab.idxNum, p->u.vtab.omitMask); } sqlite3DebugPrintf(" %-19s", z); sqlite3_free(z); } if( p->wsFlags & WHERE_SKIPSCAN ){ sqlite3DebugPrintf(" f %06x %d-%d", p->wsFlags, p->nLTerm,p->nSkip); }else{ sqlite3DebugPrintf(" f %06x N %d", p->wsFlags, p->nLTerm); } sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut); if( p->nLTerm && (sqlite3WhereTrace & 0x100)!=0 ){ int i; for(i=0; inLTerm; i++){ sqlite3WhereTermPrint(p->aLTerm[i], i); } } } #endif /* ** Convert bulk memory into a valid WhereLoop that can be passed ** to whereLoopClear harmlessly. */ static void whereLoopInit(WhereLoop *p){ p->aLTerm = p->aLTermSpace; p->nLTerm = 0; p->nLSlot = ArraySize(p->aLTermSpace); p->wsFlags = 0; } /* ** Clear the WhereLoop.u union. Leave WhereLoop.pLTerm intact. */ static void whereLoopClearUnion(sqlite3 *db, WhereLoop *p){ if( p->wsFlags & (WHERE_VIRTUALTABLE|WHERE_AUTO_INDEX) ){ if( (p->wsFlags & WHERE_VIRTUALTABLE)!=0 && p->u.vtab.needFree ){ sqlite3_free(p->u.vtab.idxStr); p->u.vtab.needFree = 0; p->u.vtab.idxStr = 0; }else if( (p->wsFlags & WHERE_AUTO_INDEX)!=0 && p->u.btree.pIndex!=0 ){ sqlite3DbFree(db, p->u.btree.pIndex->zColAff); sqlite3DbFreeNN(db, p->u.btree.pIndex); p->u.btree.pIndex = 0; } } } /* ** Deallocate internal memory used by a WhereLoop object. Leave the ** object in an initialized state, as if it had been newly allocated. */ static void whereLoopClear(sqlite3 *db, WhereLoop *p){ if( p->aLTerm!=p->aLTermSpace ){ sqlite3DbFreeNN(db, p->aLTerm); p->aLTerm = p->aLTermSpace; p->nLSlot = ArraySize(p->aLTermSpace); } whereLoopClearUnion(db, p); p->nLTerm = 0; p->wsFlags = 0; } /* ** Increase the memory allocation for pLoop->aLTerm[] to be at least n. */ static int whereLoopResize(sqlite3 *db, WhereLoop *p, int n){ WhereTerm **paNew; if( p->nLSlot>=n ) return SQLITE_OK; n = (n+7)&~7; paNew = sqlite3DbMallocRawNN(db, sizeof(p->aLTerm[0])*n); if( paNew==0 ) return SQLITE_NOMEM_BKPT; memcpy(paNew, p->aLTerm, sizeof(p->aLTerm[0])*p->nLSlot); if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFreeNN(db, p->aLTerm); p->aLTerm = paNew; p->nLSlot = n; return SQLITE_OK; } /* ** Transfer content from the second pLoop into the first. */ static int whereLoopXfer(sqlite3 *db, WhereLoop *pTo, WhereLoop *pFrom){ whereLoopClearUnion(db, pTo); if( pFrom->nLTerm > pTo->nLSlot && whereLoopResize(db, pTo, pFrom->nLTerm) ){ memset(pTo, 0, WHERE_LOOP_XFER_SZ); return SQLITE_NOMEM_BKPT; } memcpy(pTo, pFrom, WHERE_LOOP_XFER_SZ); memcpy(pTo->aLTerm, pFrom->aLTerm, pTo->nLTerm*sizeof(pTo->aLTerm[0])); if( pFrom->wsFlags & WHERE_VIRTUALTABLE ){ pFrom->u.vtab.needFree = 0; }else if( (pFrom->wsFlags & WHERE_AUTO_INDEX)!=0 ){ pFrom->u.btree.pIndex = 0; } return SQLITE_OK; } /* ** Delete a WhereLoop object */ static void whereLoopDelete(sqlite3 *db, WhereLoop *p){ assert( db!=0 ); whereLoopClear(db, p); sqlite3DbNNFreeNN(db, p); } /* ** Free a WhereInfo structure */ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){ assert( pWInfo!=0 ); assert( db!=0 ); sqlite3WhereClauseClear(&pWInfo->sWC); while( pWInfo->pLoops ){ WhereLoop *p = pWInfo->pLoops; pWInfo->pLoops = p->pNextLoop; whereLoopDelete(db, p); } while( pWInfo->pMemToFree ){ WhereMemBlock *pNext = pWInfo->pMemToFree->pNext; sqlite3DbNNFreeNN(db, pWInfo->pMemToFree); pWInfo->pMemToFree = pNext; } sqlite3DbNNFreeNN(db, pWInfo); } /* ** Return TRUE if all of the following are true: ** ** (1) X has the same or lower cost, or returns the same or fewer rows, ** than Y. ** (2) X uses fewer WHERE clause terms than Y ** (3) Every WHERE clause term used by X is also used by Y ** (4) X skips at least as many columns as Y ** (5) If X is a covering index, than Y is too ** ** Conditions (2) and (3) mean that X is a "proper subset" of Y. ** If X is a proper subset of Y then Y is a better choice and ought ** to have a lower cost. This routine returns TRUE when that cost ** relationship is inverted and needs to be adjusted. Constraint (4) ** was added because if X uses skip-scan less than Y it still might ** deserve a lower cost even if it is a proper subset of Y. Constraint (5) ** was added because a covering index probably deserves to have a lower cost ** than a non-covering index even if it is a proper subset. */ static int whereLoopCheaperProperSubset( const WhereLoop *pX, /* First WhereLoop to compare */ const WhereLoop *pY /* Compare against this WhereLoop */ ){ int i, j; if( pX->nLTerm-pX->nSkip >= pY->nLTerm-pY->nSkip ){ return 0; /* X is not a subset of Y */ } if( pX->rRun>pY->rRun && pX->nOut>pY->nOut ) return 0; if( pY->nSkip > pX->nSkip ) return 0; for(i=pX->nLTerm-1; i>=0; i--){ if( pX->aLTerm[i]==0 ) continue; for(j=pY->nLTerm-1; j>=0; j--){ if( pY->aLTerm[j]==pX->aLTerm[i] ) break; } if( j<0 ) return 0; /* X not a subset of Y since term X[i] not used by Y */ } if( (pX->wsFlags&WHERE_IDX_ONLY)!=0 && (pY->wsFlags&WHERE_IDX_ONLY)==0 ){ return 0; /* Constraint (5) */ } return 1; /* All conditions meet */ } /* ** Try to adjust the cost and number of output rows of WhereLoop pTemplate ** upwards or downwards so that: ** ** (1) pTemplate costs less than any other WhereLoops that are a proper ** subset of pTemplate ** ** (2) pTemplate costs more than any other WhereLoops for which pTemplate ** is a proper subset. ** ** To say "WhereLoop X is a proper subset of Y" means that X uses fewer ** WHERE clause terms than Y and that every WHERE clause term used by X is ** also used by Y. */ static void whereLoopAdjustCost(const WhereLoop *p, WhereLoop *pTemplate){ if( (pTemplate->wsFlags & WHERE_INDEXED)==0 ) return; for(; p; p=p->pNextLoop){ if( p->iTab!=pTemplate->iTab ) continue; if( (p->wsFlags & WHERE_INDEXED)==0 ) continue; if( whereLoopCheaperProperSubset(p, pTemplate) ){ /* Adjust pTemplate cost downward so that it is cheaper than its ** subset p. */ WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n", pTemplate->rRun, pTemplate->nOut, MIN(p->rRun, pTemplate->rRun), MIN(p->nOut - 1, pTemplate->nOut))); pTemplate->rRun = MIN(p->rRun, pTemplate->rRun); pTemplate->nOut = MIN(p->nOut - 1, pTemplate->nOut); }else if( whereLoopCheaperProperSubset(pTemplate, p) ){ /* Adjust pTemplate cost upward so that it is costlier than p since ** pTemplate is a proper subset of p */ WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n", pTemplate->rRun, pTemplate->nOut, MAX(p->rRun, pTemplate->rRun), MAX(p->nOut + 1, pTemplate->nOut))); pTemplate->rRun = MAX(p->rRun, pTemplate->rRun); pTemplate->nOut = MAX(p->nOut + 1, pTemplate->nOut); } } } /* ** Search the list of WhereLoops in *ppPrev looking for one that can be ** replaced by pTemplate. ** ** Return NULL if pTemplate does not belong on the WhereLoop list. ** In other words if pTemplate ought to be dropped from further consideration. ** ** If pX is a WhereLoop that pTemplate can replace, then return the ** link that points to pX. ** ** If pTemplate cannot replace any existing element of the list but needs ** to be added to the list as a new entry, then return a pointer to the ** tail of the list. */ static WhereLoop **whereLoopFindLesser( WhereLoop **ppPrev, const WhereLoop *pTemplate ){ WhereLoop *p; for(p=(*ppPrev); p; ppPrev=&p->pNextLoop, p=*ppPrev){ if( p->iTab!=pTemplate->iTab || p->iSortIdx!=pTemplate->iSortIdx ){ /* If either the iTab or iSortIdx values for two WhereLoop are different ** then those WhereLoops need to be considered separately. Neither is ** a candidate to replace the other. */ continue; } /* In the current implementation, the rSetup value is either zero ** or the cost of building an automatic index (NlogN) and the NlogN ** is the same for compatible WhereLoops. */ assert( p->rSetup==0 || pTemplate->rSetup==0 || p->rSetup==pTemplate->rSetup ); /* whereLoopAddBtree() always generates and inserts the automatic index ** case first. Hence compatible candidate WhereLoops never have a larger ** rSetup. Call this SETUP-INVARIANT */ assert( p->rSetup>=pTemplate->rSetup ); /* Any loop using an appliation-defined index (or PRIMARY KEY or ** UNIQUE constraint) with one or more == constraints is better ** than an automatic index. Unless it is a skip-scan. */ if( (p->wsFlags & WHERE_AUTO_INDEX)!=0 && (pTemplate->nSkip)==0 && (pTemplate->wsFlags & WHERE_INDEXED)!=0 && (pTemplate->wsFlags & WHERE_COLUMN_EQ)!=0 && (p->prereq & pTemplate->prereq)==pTemplate->prereq ){ break; } /* If existing WhereLoop p is better than pTemplate, pTemplate can be ** discarded. WhereLoop p is better if: ** (1) p has no more dependencies than pTemplate, and ** (2) p has an equal or lower cost than pTemplate */ if( (p->prereq & pTemplate->prereq)==p->prereq /* (1) */ && p->rSetup<=pTemplate->rSetup /* (2a) */ && p->rRun<=pTemplate->rRun /* (2b) */ && p->nOut<=pTemplate->nOut /* (2c) */ ){ return 0; /* Discard pTemplate */ } /* If pTemplate is always better than p, then cause p to be overwritten ** with pTemplate. pTemplate is better than p if: ** (1) pTemplate has no more dependences than p, and ** (2) pTemplate has an equal or lower cost than p. */ if( (p->prereq & pTemplate->prereq)==pTemplate->prereq /* (1) */ && p->rRun>=pTemplate->rRun /* (2a) */ && p->nOut>=pTemplate->nOut /* (2b) */ ){ assert( p->rSetup>=pTemplate->rSetup ); /* SETUP-INVARIANT above */ break; /* Cause p to be overwritten by pTemplate */ } } return ppPrev; } /* ** Insert or replace a WhereLoop entry using the template supplied. ** ** An existing WhereLoop entry might be overwritten if the new template ** is better and has fewer dependencies. Or the template will be ignored ** and no insert will occur if an existing WhereLoop is faster and has ** fewer dependencies than the template. Otherwise a new WhereLoop is ** added based on the template. ** ** If pBuilder->pOrSet is not NULL then we care about only the ** prerequisites and rRun and nOut costs of the N best loops. That ** information is gathered in the pBuilder->pOrSet object. This special ** processing mode is used only for OR clause processing. ** ** When accumulating multiple loops (when pBuilder->pOrSet is NULL) we ** still might overwrite similar loops with the new template if the ** new template is better. Loops may be overwritten if the following ** conditions are met: ** ** (1) They have the same iTab. ** (2) They have the same iSortIdx. ** (3) The template has same or fewer dependencies than the current loop ** (4) The template has the same or lower cost than the current loop */ static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){ WhereLoop **ppPrev, *p; WhereInfo *pWInfo = pBuilder->pWInfo; sqlite3 *db = pWInfo->pParse->db; int rc; /* Stop the search once we hit the query planner search limit */ if( pBuilder->iPlanLimit==0 ){ WHERETRACE(0xffffffff,("=== query planner search limit reached ===\n")); if( pBuilder->pOrSet ) pBuilder->pOrSet->n = 0; return SQLITE_DONE; } pBuilder->iPlanLimit--; whereLoopAdjustCost(pWInfo->pLoops, pTemplate); /* If pBuilder->pOrSet is defined, then only keep track of the costs ** and prereqs. */ if( pBuilder->pOrSet!=0 ){ if( pTemplate->nLTerm ){ #if WHERETRACE_ENABLED u16 n = pBuilder->pOrSet->n; int x = #endif whereOrInsert(pBuilder->pOrSet, pTemplate->prereq, pTemplate->rRun, pTemplate->nOut); #if WHERETRACE_ENABLED /* 0x8 */ if( sqlite3WhereTrace & 0x8 ){ sqlite3DebugPrintf(x?" or-%d: ":" or-X: ", n); sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC); } #endif } return SQLITE_OK; } /* Look for an existing WhereLoop to replace with pTemplate */ ppPrev = whereLoopFindLesser(&pWInfo->pLoops, pTemplate); if( ppPrev==0 ){ /* There already exists a WhereLoop on the list that is better ** than pTemplate, so just ignore pTemplate */ #if WHERETRACE_ENABLED /* 0x8 */ if( sqlite3WhereTrace & 0x8 ){ sqlite3DebugPrintf(" skip: "); sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC); } #endif return SQLITE_OK; }else{ p = *ppPrev; } /* If we reach this point it means that either p[] should be overwritten ** with pTemplate[] if p[] exists, or if p==NULL then allocate a new ** WhereLoop and insert it. */ #if WHERETRACE_ENABLED /* 0x8 */ if( sqlite3WhereTrace & 0x8 ){ if( p!=0 ){ sqlite3DebugPrintf("replace: "); sqlite3WhereLoopPrint(p, pBuilder->pWC); sqlite3DebugPrintf(" with: "); }else{ sqlite3DebugPrintf(" add: "); } sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC); } #endif if( p==0 ){ /* Allocate a new WhereLoop to add to the end of the list */ *ppPrev = p = sqlite3DbMallocRawNN(db, sizeof(WhereLoop)); if( p==0 ) return SQLITE_NOMEM_BKPT; whereLoopInit(p); p->pNextLoop = 0; }else{ /* We will be overwriting WhereLoop p[]. But before we do, first ** go through the rest of the list and delete any other entries besides ** p[] that are also supplated by pTemplate */ WhereLoop **ppTail = &p->pNextLoop; WhereLoop *pToDel; while( *ppTail ){ ppTail = whereLoopFindLesser(ppTail, pTemplate); if( ppTail==0 ) break; pToDel = *ppTail; if( pToDel==0 ) break; *ppTail = pToDel->pNextLoop; #if WHERETRACE_ENABLED /* 0x8 */ if( sqlite3WhereTrace & 0x8 ){ sqlite3DebugPrintf(" delete: "); sqlite3WhereLoopPrint(pToDel, pBuilder->pWC); } #endif whereLoopDelete(db, pToDel); } } rc = whereLoopXfer(db, p, pTemplate); if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){ Index *pIndex = p->u.btree.pIndex; if( pIndex && pIndex->idxType==SQLITE_IDXTYPE_IPK ){ p->u.btree.pIndex = 0; } } return rc; } /* ** Adjust the WhereLoop.nOut value downward to account for terms of the ** WHERE clause that reference the loop but which are not used by an ** index. * ** For every WHERE clause term that is not used by the index ** and which has a truth probability assigned by one of the likelihood(), ** likely(), or unlikely() SQL functions, reduce the estimated number ** of output rows by the probability specified. ** ** TUNING: For every WHERE clause term that is not used by the index ** and which does not have an assigned truth probability, heuristics ** described below are used to try to estimate the truth probability. ** TODO --> Perhaps this is something that could be improved by better ** table statistics. ** ** Heuristic 1: Estimate the truth probability as 93.75%. The 93.75% ** value corresponds to -1 in LogEst notation, so this means decrement ** the WhereLoop.nOut field for every such WHERE clause term. ** ** Heuristic 2: If there exists one or more WHERE clause terms of the ** form "x==EXPR" and EXPR is not a constant 0 or 1, then make sure the ** final output row estimate is no greater than 1/4 of the total number ** of rows in the table. In other words, assume that x==EXPR will filter ** out at least 3 out of 4 rows. If EXPR is -1 or 0 or 1, then maybe the ** "x" column is boolean or else -1 or 0 or 1 is a common default value ** on the "x" column and so in that case only cap the output row estimate ** at 1/2 instead of 1/4. */ static void whereLoopOutputAdjust( WhereClause *pWC, /* The WHERE clause */ WhereLoop *pLoop, /* The loop to adjust downward */ LogEst nRow /* Number of rows in the entire table */ ){ WhereTerm *pTerm, *pX; Bitmask notAllowed = ~(pLoop->prereq|pLoop->maskSelf); int i, j; LogEst iReduce = 0; /* pLoop->nOut should not exceed nRow-iReduce */ assert( (pLoop->wsFlags & WHERE_AUTO_INDEX)==0 ); for(i=pWC->nBase, pTerm=pWC->a; i>0; i--, pTerm++){ assert( pTerm!=0 ); if( (pTerm->prereqAll & notAllowed)!=0 ) continue; if( (pTerm->prereqAll & pLoop->maskSelf)==0 ) continue; if( (pTerm->wtFlags & TERM_VIRTUAL)!=0 ) continue; for(j=pLoop->nLTerm-1; j>=0; j--){ pX = pLoop->aLTerm[j]; if( pX==0 ) continue; if( pX==pTerm ) break; if( pX->iParent>=0 && (&pWC->a[pX->iParent])==pTerm ) break; } if( j<0 ){ if( pLoop->maskSelf==pTerm->prereqAll ){ /* If there are extra terms in the WHERE clause not used by an index ** that depend only on the table being scanned, and that will tend to ** cause many rows to be omitted, then mark that table as ** "self-culling". ** ** 2022-03-24: Self-culling only applies if either the extra terms ** are straight comparison operators that are non-true with NULL ** operand, or if the loop is not an OUTER JOIN. */ if( (pTerm->eOperator & 0x3f)!=0 || (pWC->pWInfo->pTabList->a[pLoop->iTab].fg.jointype & (JT_LEFT|JT_LTORJ))==0 ){ pLoop->wsFlags |= WHERE_SELFCULL; } } if( pTerm->truthProb<=0 ){ /* If a truth probability is specified using the likelihood() hints, ** then use the probability provided by the application. */ pLoop->nOut += pTerm->truthProb; }else{ /* In the absence of explicit truth probabilities, use heuristics to ** guess a reasonable truth probability. */ pLoop->nOut--; if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && (pTerm->wtFlags & TERM_HIGHTRUTH)==0 /* tag-20200224-1 */ ){ Expr *pRight = pTerm->pExpr->pRight; int k = 0; testcase( pTerm->pExpr->op==TK_IS ); if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){ k = 10; }else{ k = 20; } if( iReducewtFlags |= TERM_HEURTRUTH; iReduce = k; } } } } } if( pLoop->nOut > nRow-iReduce ){ pLoop->nOut = nRow - iReduce; } } /* ** Term pTerm is a vector range comparison operation. The first comparison ** in the vector can be optimized using column nEq of the index. This ** function returns the total number of vector elements that can be used ** as part of the range comparison. ** ** For example, if the query is: ** ** WHERE a = ? AND (b, c, d) > (?, ?, ?) ** ** and the index: ** ** CREATE INDEX ... ON (a, b, c, d, e) ** ** then this function would be invoked with nEq=1. The value returned in ** this case is 3. */ static int whereRangeVectorLen( Parse *pParse, /* Parsing context */ int iCur, /* Cursor open on pIdx */ Index *pIdx, /* The index to be used for a inequality constraint */ int nEq, /* Number of prior equality constraints on same index */ WhereTerm *pTerm /* The vector inequality constraint */ ){ int nCmp = sqlite3ExprVectorSize(pTerm->pExpr->pLeft); int i; nCmp = MIN(nCmp, (pIdx->nColumn - nEq)); for(i=1; ipExpr->pLeft) ); pLhs = pTerm->pExpr->pLeft->x.pList->a[i].pExpr; pRhs = pTerm->pExpr->pRight; if( ExprUseXSelect(pRhs) ){ pRhs = pRhs->x.pSelect->pEList->a[i].pExpr; }else{ pRhs = pRhs->x.pList->a[i].pExpr; } /* Check that the LHS of the comparison is a column reference to ** the right column of the right source table. And that the sort ** order of the index column is the same as the sort order of the ** leftmost index column. */ if( pLhs->op!=TK_COLUMN || pLhs->iTable!=iCur || pLhs->iColumn!=pIdx->aiColumn[i+nEq] || pIdx->aSortOrder[i+nEq]!=pIdx->aSortOrder[nEq] ){ break; } testcase( pLhs->iColumn==XN_ROWID ); aff = sqlite3CompareAffinity(pRhs, sqlite3ExprAffinity(pLhs)); idxaff = sqlite3TableColumnAffinity(pIdx->pTable, pLhs->iColumn); if( aff!=idxaff ) break; pColl = sqlite3BinaryCompareCollSeq(pParse, pLhs, pRhs); if( pColl==0 ) break; if( sqlite3StrICmp(pColl->zName, pIdx->azColl[i+nEq]) ) break; } return i; } /* ** Adjust the cost C by the costMult facter T. This only occurs if ** compiled with -DSQLITE_ENABLE_COSTMULT */ #ifdef SQLITE_ENABLE_COSTMULT # define ApplyCostMultiplier(C,T) C += T #else # define ApplyCostMultiplier(C,T) #endif /* ** We have so far matched pBuilder->pNew->u.btree.nEq terms of the ** index pIndex. Try to match one more. ** ** When this function is called, pBuilder->pNew->nOut contains the ** number of rows expected to be visited by filtering using the nEq ** terms only. If it is modified, this value is restored before this ** function returns. ** ** If pProbe->idxType==SQLITE_IDXTYPE_IPK, that means pIndex is ** a fake index used for the INTEGER PRIMARY KEY. */ static int whereLoopAddBtreeIndex( WhereLoopBuilder *pBuilder, /* The WhereLoop factory */ SrcItem *pSrc, /* FROM clause term being analyzed */ Index *pProbe, /* An index on pSrc */ LogEst nInMul /* log(Number of iterations due to IN) */ ){ WhereInfo *pWInfo = pBuilder->pWInfo; /* WHERE analyse context */ Parse *pParse = pWInfo->pParse; /* Parsing context */ sqlite3 *db = pParse->db; /* Database connection malloc context */ WhereLoop *pNew; /* Template WhereLoop under construction */ WhereTerm *pTerm; /* A WhereTerm under consideration */ int opMask; /* Valid operators for constraints */ WhereScan scan; /* Iterator for WHERE terms */ Bitmask saved_prereq; /* Original value of pNew->prereq */ u16 saved_nLTerm; /* Original value of pNew->nLTerm */ u16 saved_nEq; /* Original value of pNew->u.btree.nEq */ u16 saved_nBtm; /* Original value of pNew->u.btree.nBtm */ u16 saved_nTop; /* Original value of pNew->u.btree.nTop */ u16 saved_nSkip; /* Original value of pNew->nSkip */ u32 saved_wsFlags; /* Original value of pNew->wsFlags */ LogEst saved_nOut; /* Original value of pNew->nOut */ int rc = SQLITE_OK; /* Return code */ LogEst rSize; /* Number of rows in the table */ LogEst rLogSize; /* Logarithm of table size */ WhereTerm *pTop = 0, *pBtm = 0; /* Top and bottom range constraints */ pNew = pBuilder->pNew; if( db->mallocFailed ) return SQLITE_NOMEM_BKPT; WHERETRACE(0x800, ("BEGIN %s.addBtreeIdx(%s), nEq=%d, nSkip=%d, rRun=%d\n", pProbe->pTable->zName,pProbe->zName, pNew->u.btree.nEq, pNew->nSkip, pNew->rRun)); assert( (pNew->wsFlags & WHERE_VIRTUALTABLE)==0 ); assert( (pNew->wsFlags & WHERE_TOP_LIMIT)==0 ); if( pNew->wsFlags & WHERE_BTM_LIMIT ){ opMask = WO_LT|WO_LE; }else{ assert( pNew->u.btree.nBtm==0 ); opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE|WO_ISNULL|WO_IS; } if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE); assert( pNew->u.btree.nEqnColumn ); assert( pNew->u.btree.nEqnKeyCol || pProbe->idxType!=SQLITE_IDXTYPE_PRIMARYKEY ); saved_nEq = pNew->u.btree.nEq; saved_nBtm = pNew->u.btree.nBtm; saved_nTop = pNew->u.btree.nTop; saved_nSkip = pNew->nSkip; saved_nLTerm = pNew->nLTerm; saved_wsFlags = pNew->wsFlags; saved_prereq = pNew->prereq; saved_nOut = pNew->nOut; pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, saved_nEq, opMask, pProbe); pNew->rSetup = 0; rSize = pProbe->aiRowLogEst[0]; rLogSize = estLog(rSize); for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){ u16 eOp = pTerm->eOperator; /* Shorthand for pTerm->eOperator */ LogEst rCostIdx; LogEst nOutUnadjusted; /* nOut before IN() and WHERE adjustments */ int nIn = 0; #ifdef SQLITE_ENABLE_STAT4 int nRecValid = pBuilder->nRecValid; #endif if( (eOp==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0) && indexColumnNotNull(pProbe, saved_nEq) ){ continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */ } if( pTerm->prereqRight & pNew->maskSelf ) continue; /* Do not allow the upper bound of a LIKE optimization range constraint ** to mix with a lower range bound from some other source */ if( pTerm->wtFlags & TERM_LIKEOPT && pTerm->eOperator==WO_LT ) continue; if( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0 && !constraintCompatibleWithOuterJoin(pTerm,pSrc) ){ continue; } if( IsUniqueIndex(pProbe) && saved_nEq==pProbe->nKeyCol-1 ){ pBuilder->bldFlags1 |= SQLITE_BLDF1_UNIQUE; }else{ pBuilder->bldFlags1 |= SQLITE_BLDF1_INDEXED; } pNew->wsFlags = saved_wsFlags; pNew->u.btree.nEq = saved_nEq; pNew->u.btree.nBtm = saved_nBtm; pNew->u.btree.nTop = saved_nTop; pNew->nLTerm = saved_nLTerm; if( pNew->nLTerm>=pNew->nLSlot && whereLoopResize(db, pNew, pNew->nLTerm+1) ){ break; /* OOM while trying to enlarge the pNew->aLTerm array */ } pNew->aLTerm[pNew->nLTerm++] = pTerm; pNew->prereq = (saved_prereq | pTerm->prereqRight) & ~pNew->maskSelf; assert( nInMul==0 || (pNew->wsFlags & WHERE_COLUMN_NULL)!=0 || (pNew->wsFlags & WHERE_COLUMN_IN)!=0 || (pNew->wsFlags & WHERE_SKIPSCAN)!=0 ); if( eOp & WO_IN ){ Expr *pExpr = pTerm->pExpr; if( ExprUseXSelect(pExpr) ){ /* "x IN (SELECT ...)": TUNING: the SELECT returns 25 rows */ int i; nIn = 46; assert( 46==sqlite3LogEst(25) ); /* The expression may actually be of the form (x, y) IN (SELECT...). ** In this case there is a separate term for each of (x) and (y). ** However, the nIn multiplier should only be applied once, not once ** for each such term. The following loop checks that pTerm is the ** first such term in use, and sets nIn back to 0 if it is not. */ for(i=0; inLTerm-1; i++){ if( pNew->aLTerm[i] && pNew->aLTerm[i]->pExpr==pExpr ) nIn = 0; } }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){ /* "x IN (value, value, ...)" */ nIn = sqlite3LogEst(pExpr->x.pList->nExpr); } if( pProbe->hasStat1 && rLogSize>=10 ){ LogEst M, logK, x; /* Let: ** N = the total number of rows in the table ** K = the number of entries on the RHS of the IN operator ** M = the number of rows in the table that match terms to the ** to the left in the same index. If the IN operator is on ** the left-most index column, M==N. ** ** Given the definitions above, it is better to omit the IN operator ** from the index lookup and instead do a scan of the M elements, ** testing each scanned row against the IN operator separately, if: ** ** M*log(K) < K*log(N) ** ** Our estimates for M, K, and N might be inaccurate, so we build in ** a safety margin of 2 (LogEst: 10) that favors using the IN operator ** with the index, as using an index has better worst-case behavior. ** If we do not have real sqlite_stat1 data, always prefer to use ** the index. Do not bother with this optimization on very small ** tables (less than 2 rows) as it is pointless in that case. */ M = pProbe->aiRowLogEst[saved_nEq]; logK = estLog(nIn); /* TUNING v----- 10 to bias toward indexed IN */ x = M + logK + 10 - (nIn + rLogSize); if( x>=0 ){ WHERETRACE(0x40, ("IN operator (N=%d M=%d logK=%d nIn=%d rLogSize=%d x=%d) " "prefers indexed lookup\n", saved_nEq, M, logK, nIn, rLogSize, x)); }else if( nInMul<2 && OptimizationEnabled(db, SQLITE_SeekScan) ){ WHERETRACE(0x40, ("IN operator (N=%d M=%d logK=%d nIn=%d rLogSize=%d x=%d" " nInMul=%d) prefers skip-scan\n", saved_nEq, M, logK, nIn, rLogSize, x, nInMul)); pNew->wsFlags |= WHERE_IN_SEEKSCAN; }else{ WHERETRACE(0x40, ("IN operator (N=%d M=%d logK=%d nIn=%d rLogSize=%d x=%d" " nInMul=%d) prefers normal scan\n", saved_nEq, M, logK, nIn, rLogSize, x, nInMul)); continue; } } pNew->wsFlags |= WHERE_COLUMN_IN; }else if( eOp & (WO_EQ|WO_IS) ){ int iCol = pProbe->aiColumn[saved_nEq]; pNew->wsFlags |= WHERE_COLUMN_EQ; assert( saved_nEq==pNew->u.btree.nEq ); if( iCol==XN_ROWID || (iCol>=0 && nInMul==0 && saved_nEq==pProbe->nKeyCol-1) ){ if( iCol==XN_ROWID || pProbe->uniqNotNull || (pProbe->nKeyCol==1 && pProbe->onError && eOp==WO_EQ) ){ pNew->wsFlags |= WHERE_ONEROW; }else{ pNew->wsFlags |= WHERE_UNQ_WANTED; } } if( scan.iEquiv>1 ) pNew->wsFlags |= WHERE_TRANSCONS; }else if( eOp & WO_ISNULL ){ pNew->wsFlags |= WHERE_COLUMN_NULL; }else{ int nVecLen = whereRangeVectorLen( pParse, pSrc->iCursor, pProbe, saved_nEq, pTerm ); if( eOp & (WO_GT|WO_GE) ){ testcase( eOp & WO_GT ); testcase( eOp & WO_GE ); pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_BTM_LIMIT; pNew->u.btree.nBtm = nVecLen; pBtm = pTerm; pTop = 0; if( pTerm->wtFlags & TERM_LIKEOPT ){ /* Range constraints that come from the LIKE optimization are ** always used in pairs. */ pTop = &pTerm[1]; assert( (pTop-(pTerm->pWC->a))pWC->nTerm ); assert( pTop->wtFlags & TERM_LIKEOPT ); assert( pTop->eOperator==WO_LT ); if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */ pNew->aLTerm[pNew->nLTerm++] = pTop; pNew->wsFlags |= WHERE_TOP_LIMIT; pNew->u.btree.nTop = 1; } }else{ assert( eOp & (WO_LT|WO_LE) ); testcase( eOp & WO_LT ); testcase( eOp & WO_LE ); pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_TOP_LIMIT; pNew->u.btree.nTop = nVecLen; pTop = pTerm; pBtm = (pNew->wsFlags & WHERE_BTM_LIMIT)!=0 ? pNew->aLTerm[pNew->nLTerm-2] : 0; } } /* At this point pNew->nOut is set to the number of rows expected to ** be visited by the index scan before considering term pTerm, or the ** values of nIn and nInMul. In other words, assuming that all ** "x IN(...)" terms are replaced with "x = ?". This block updates ** the value of pNew->nOut to account for pTerm (but not nIn/nInMul). */ assert( pNew->nOut==saved_nOut ); if( pNew->wsFlags & WHERE_COLUMN_RANGE ){ /* Adjust nOut using stat4 data. Or, if there is no stat4 ** data, using some other estimate. */ whereRangeScanEst(pParse, pBuilder, pBtm, pTop, pNew); }else{ int nEq = ++pNew->u.btree.nEq; assert( eOp & (WO_ISNULL|WO_EQ|WO_IN|WO_IS) ); assert( pNew->nOut==saved_nOut ); if( pTerm->truthProb<=0 && pProbe->aiColumn[saved_nEq]>=0 ){ assert( (eOp & WO_IN) || nIn==0 ); testcase( eOp & WO_IN ); pNew->nOut += pTerm->truthProb; pNew->nOut -= nIn; }else{ #ifdef SQLITE_ENABLE_STAT4 tRowcnt nOut = 0; if( nInMul==0 && pProbe->nSample && ALWAYS(pNew->u.btree.nEq<=pProbe->nSampleCol) && ((eOp & WO_IN)==0 || ExprUseXList(pTerm->pExpr)) && OptimizationEnabled(db, SQLITE_Stat4) ){ Expr *pExpr = pTerm->pExpr; if( (eOp & (WO_EQ|WO_ISNULL|WO_IS))!=0 ){ testcase( eOp & WO_EQ ); testcase( eOp & WO_IS ); testcase( eOp & WO_ISNULL ); rc = whereEqualScanEst(pParse, pBuilder, pExpr->pRight, &nOut); }else{ rc = whereInScanEst(pParse, pBuilder, pExpr->x.pList, &nOut); } if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK; if( rc!=SQLITE_OK ) break; /* Jump out of the pTerm loop */ if( nOut ){ pNew->nOut = sqlite3LogEst(nOut); if( nEq==1 /* TUNING: Mark terms as "low selectivity" if they seem likely ** to be true for half or more of the rows in the table. ** See tag-202002240-1 */ && pNew->nOut+10 > pProbe->aiRowLogEst[0] ){ #if WHERETRACE_ENABLED /* 0x01 */ if( sqlite3WhereTrace & 0x01 ){ sqlite3DebugPrintf( "STAT4 determines term has low selectivity:\n"); sqlite3WhereTermPrint(pTerm, 999); } #endif pTerm->wtFlags |= TERM_HIGHTRUTH; if( pTerm->wtFlags & TERM_HEURTRUTH ){ /* If the term has previously been used with an assumption of ** higher selectivity, then set the flag to rerun the ** loop computations. */ pBuilder->bldFlags2 |= SQLITE_BLDF2_2NDPASS; } } if( pNew->nOut>saved_nOut ) pNew->nOut = saved_nOut; pNew->nOut -= nIn; } } if( nOut==0 ) #endif { pNew->nOut += (pProbe->aiRowLogEst[nEq] - pProbe->aiRowLogEst[nEq-1]); if( eOp & WO_ISNULL ){ /* TUNING: If there is no likelihood() value, assume that a ** "col IS NULL" expression matches twice as many rows ** as (col=?). */ pNew->nOut += 10; } } } } /* Set rCostIdx to the cost of visiting selected rows in index. Add ** it to pNew->rRun, which is currently set to the cost of the index ** seek only. Then, if this is a non-covering index, add the cost of ** visiting the rows in the main table. */ assert( pSrc->pTab->szTabRow>0 ); rCostIdx = pNew->nOut + 1 + (15*pProbe->szIdxRow)/pSrc->pTab->szTabRow; pNew->rRun = sqlite3LogEstAdd(rLogSize, rCostIdx); if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){ pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut + 16); } ApplyCostMultiplier(pNew->rRun, pProbe->pTable->costMult); nOutUnadjusted = pNew->nOut; pNew->rRun += nInMul + nIn; pNew->nOut += nInMul + nIn; whereLoopOutputAdjust(pBuilder->pWC, pNew, rSize); rc = whereLoopInsert(pBuilder, pNew); if( pNew->wsFlags & WHERE_COLUMN_RANGE ){ pNew->nOut = saved_nOut; }else{ pNew->nOut = nOutUnadjusted; } if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0 && pNew->u.btree.nEqnColumn && (pNew->u.btree.nEqnKeyCol || pProbe->idxType!=SQLITE_IDXTYPE_PRIMARYKEY) ){ whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn); } pNew->nOut = saved_nOut; #ifdef SQLITE_ENABLE_STAT4 pBuilder->nRecValid = nRecValid; #endif } pNew->prereq = saved_prereq; pNew->u.btree.nEq = saved_nEq; pNew->u.btree.nBtm = saved_nBtm; pNew->u.btree.nTop = saved_nTop; pNew->nSkip = saved_nSkip; pNew->wsFlags = saved_wsFlags; pNew->nOut = saved_nOut; pNew->nLTerm = saved_nLTerm; /* Consider using a skip-scan if there are no WHERE clause constraints ** available for the left-most terms of the index, and if the average ** number of repeats in the left-most terms is at least 18. ** ** The magic number 18 is selected on the basis that scanning 17 rows ** is almost always quicker than an index seek (even though if the index ** contains fewer than 2^17 rows we assume otherwise in other parts of ** the code). And, even if it is not, it should not be too much slower. ** On the other hand, the extra seeks could end up being significantly ** more expensive. */ assert( 42==sqlite3LogEst(18) ); if( saved_nEq==saved_nSkip && saved_nEq+1nKeyCol && saved_nEq==pNew->nLTerm && pProbe->noSkipScan==0 && pProbe->hasStat1!=0 && OptimizationEnabled(db, SQLITE_SkipScan) && pProbe->aiRowLogEst[saved_nEq+1]>=42 /* TUNING: Minimum for skip-scan */ && (rc = whereLoopResize(db, pNew, pNew->nLTerm+1))==SQLITE_OK ){ LogEst nIter; pNew->u.btree.nEq++; pNew->nSkip++; pNew->aLTerm[pNew->nLTerm++] = 0; pNew->wsFlags |= WHERE_SKIPSCAN; nIter = pProbe->aiRowLogEst[saved_nEq] - pProbe->aiRowLogEst[saved_nEq+1]; pNew->nOut -= nIter; /* TUNING: Because uncertainties in the estimates for skip-scan queries, ** add a 1.375 fudge factor to make skip-scan slightly less likely. */ nIter += 5; whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nIter + nInMul); pNew->nOut = saved_nOut; pNew->u.btree.nEq = saved_nEq; pNew->nSkip = saved_nSkip; pNew->wsFlags = saved_wsFlags; } WHERETRACE(0x800, ("END %s.addBtreeIdx(%s), nEq=%d, rc=%d\n", pProbe->pTable->zName, pProbe->zName, saved_nEq, rc)); return rc; } /* ** Return True if it is possible that pIndex might be useful in ** implementing the ORDER BY clause in pBuilder. ** ** Return False if pBuilder does not contain an ORDER BY clause or ** if there is no way for pIndex to be useful in implementing that ** ORDER BY clause. */ static int indexMightHelpWithOrderBy( WhereLoopBuilder *pBuilder, Index *pIndex, int iCursor ){ ExprList *pOB; ExprList *aColExpr; int ii, jj; if( pIndex->bUnordered ) return 0; if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0; for(ii=0; iinExpr; ii++){ Expr *pExpr = sqlite3ExprSkipCollateAndLikely(pOB->a[ii].pExpr); if( NEVER(pExpr==0) ) continue; if( pExpr->op==TK_COLUMN && pExpr->iTable==iCursor ){ if( pExpr->iColumn<0 ) return 1; for(jj=0; jjnKeyCol; jj++){ if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1; } }else if( (aColExpr = pIndex->aColExpr)!=0 ){ for(jj=0; jjnKeyCol; jj++){ if( pIndex->aiColumn[jj]!=XN_EXPR ) continue; if( sqlite3ExprCompareSkip(pExpr,aColExpr->a[jj].pExpr,iCursor)==0 ){ return 1; } } } } return 0; } /* Check to see if a partial index with pPartIndexWhere can be used ** in the current query. Return true if it can be and false if not. */ static int whereUsablePartialIndex( int iTab, /* The table for which we want an index */ u8 jointype, /* The JT_* flags on the join */ WhereClause *pWC, /* The WHERE clause of the query */ Expr *pWhere /* The WHERE clause from the partial index */ ){ int i; WhereTerm *pTerm; Parse *pParse; if( jointype & JT_LTORJ ) return 0; pParse = pWC->pWInfo->pParse; while( pWhere->op==TK_AND ){ if( !whereUsablePartialIndex(iTab,jointype,pWC,pWhere->pLeft) ) return 0; pWhere = pWhere->pRight; } if( pParse->db->flags & SQLITE_EnableQPSG ) pParse = 0; for(i=0, pTerm=pWC->a; inTerm; i++, pTerm++){ Expr *pExpr; pExpr = pTerm->pExpr; if( (!ExprHasProperty(pExpr, EP_OuterON) || pExpr->w.iJoin==iTab) && ((jointype & JT_OUTER)==0 || ExprHasProperty(pExpr, EP_OuterON)) && sqlite3ExprImpliesExpr(pParse, pExpr, pWhere, iTab) && (pTerm->wtFlags & TERM_VNULL)==0 ){ return 1; } } return 0; } /* ** Structure passed to the whereIsCoveringIndex Walker callback. */ struct CoveringIndexCheck { Index *pIdx; /* The index */ int iTabCur; /* Cursor number for the corresponding table */ }; /* ** Information passed in is pWalk->u.pCovIdxCk. Call is pCk. ** ** If the Expr node references the table with cursor pCk->iTabCur, then ** make sure that column is covered by the index pCk->pIdx. We know that ** all columns less than 63 (really BMS-1) are covered, so we don't need ** to check them. But we do need to check any column at 63 or greater. ** ** If the index does not cover the column, then set pWalk->eCode to ** non-zero and return WRC_Abort to stop the search. ** ** If this node does not disprove that the index can be a covering index, ** then just return WRC_Continue, to continue the search. */ static int whereIsCoveringIndexWalkCallback(Walker *pWalk, Expr *pExpr){ int i; /* Loop counter */ const Index *pIdx; /* The index of interest */ const i16 *aiColumn; /* Columns contained in the index */ u16 nColumn; /* Number of columns in the index */ if( pExpr->op!=TK_COLUMN && pExpr->op!=TK_AGG_COLUMN ) return WRC_Continue; if( pExpr->iColumn<(BMS-1) ) return WRC_Continue; if( pExpr->iTable!=pWalk->u.pCovIdxCk->iTabCur ) return WRC_Continue; pIdx = pWalk->u.pCovIdxCk->pIdx; aiColumn = pIdx->aiColumn; nColumn = pIdx->nColumn; for(i=0; iiColumn ) return WRC_Continue; } pWalk->eCode = 1; return WRC_Abort; } /* ** pIdx is an index that covers all of the low-number columns used by ** pWInfo->pSelect (columns from 0 through 62). But there are columns ** in pWInfo->pSelect beyond 62. This routine tries to answer the question ** of whether pIdx covers *all* columns in the query. ** ** Return 0 if pIdx is a covering index. Return non-zero if pIdx is ** not a covering index or if we are unable to determine if pIdx is a ** covering index. ** ** This routine is an optimization. It is always safe to return non-zero. ** But returning zero when non-zero should have been returned can lead to ** incorrect bytecode and assertion faults. */ static SQLITE_NOINLINE u32 whereIsCoveringIndex( WhereInfo *pWInfo, /* The WHERE clause context */ Index *pIdx, /* Index that is being tested */ int iTabCur /* Cursor for the table being indexed */ ){ int i; struct CoveringIndexCheck ck; Walker w; if( pWInfo->pSelect==0 ){ /* We don't have access to the full query, so we cannot check to see ** if pIdx is covering. Assume it is not. */ return 1; } for(i=0; inColumn; i++){ if( pIdx->aiColumn[i]>=BMS-1 ) break; } if( i>=pIdx->nColumn ){ /* pIdx does not index any columns greater than 62, but we know from ** colMask that columns greater than 62 are used, so this is not a ** covering index */ return 1; } ck.pIdx = pIdx; ck.iTabCur = iTabCur; memset(&w, 0, sizeof(w)); w.xExprCallback = whereIsCoveringIndexWalkCallback; w.xSelectCallback = sqlite3SelectWalkNoop; w.u.pCovIdxCk = &ck; w.eCode = 0; sqlite3WalkSelect(&w, pWInfo->pSelect); return w.eCode; } /* ** Add all WhereLoop objects for a single table of the join where the table ** is identified by pBuilder->pNew->iTab. That table is guaranteed to be ** a b-tree table, not a virtual table. ** ** The costs (WhereLoop.rRun) of the b-tree loops added by this function ** are calculated as follows: ** ** For a full scan, assuming the table (or index) contains nRow rows: ** ** cost = nRow * 3.0 // full-table scan ** cost = nRow * K // scan of covering index ** cost = nRow * (K+3.0) // scan of non-covering index ** ** where K is a value between 1.1 and 3.0 set based on the relative ** estimated average size of the index and table records. ** ** For an index scan, where nVisit is the number of index rows visited ** by the scan, and nSeek is the number of seek operations required on ** the index b-tree: ** ** cost = nSeek * (log(nRow) + K * nVisit) // covering index ** cost = nSeek * (log(nRow) + (K+3.0) * nVisit) // non-covering index ** ** Normally, nSeek is 1. nSeek values greater than 1 come about if the ** WHERE clause includes "x IN (....)" terms used in place of "x=?". Or when ** implicit "x IN (SELECT x FROM tbl)" terms are added for skip-scans. ** ** The estimated values (nRow, nVisit, nSeek) often contain a large amount ** of uncertainty. For this reason, scoring is designed to pick plans that ** "do the least harm" if the estimates are inaccurate. For example, a ** log(nRow) factor is omitted from a non-covering index scan in order to ** bias the scoring in favor of using an index, since the worst-case ** performance of using an index is far better than the worst-case performance ** of a full table scan. */ static int whereLoopAddBtree( WhereLoopBuilder *pBuilder, /* WHERE clause information */ Bitmask mPrereq /* Extra prerequesites for using this table */ ){ WhereInfo *pWInfo; /* WHERE analysis context */ Index *pProbe; /* An index we are evaluating */ Index sPk; /* A fake index object for the primary key */ LogEst aiRowEstPk[2]; /* The aiRowLogEst[] value for the sPk index */ i16 aiColumnPk = -1; /* The aColumn[] value for the sPk index */ SrcList *pTabList; /* The FROM clause */ SrcItem *pSrc; /* The FROM clause btree term to add */ WhereLoop *pNew; /* Template WhereLoop object */ int rc = SQLITE_OK; /* Return code */ int iSortIdx = 1; /* Index number */ int b; /* A boolean value */ LogEst rSize; /* number of rows in the table */ WhereClause *pWC; /* The parsed WHERE clause */ Table *pTab; /* Table being queried */ pNew = pBuilder->pNew; pWInfo = pBuilder->pWInfo; pTabList = pWInfo->pTabList; pSrc = pTabList->a + pNew->iTab; pTab = pSrc->pTab; pWC = pBuilder->pWC; assert( !IsVirtual(pSrc->pTab) ); if( pSrc->fg.isIndexedBy ){ assert( pSrc->fg.isCte==0 ); /* An INDEXED BY clause specifies a particular index to use */ pProbe = pSrc->u2.pIBIndex; }else if( !HasRowid(pTab) ){ pProbe = pTab->pIndex; }else{ /* There is no INDEXED BY clause. Create a fake Index object in local ** variable sPk to represent the rowid primary key index. Make this ** fake index the first in a chain of Index objects with all of the real ** indices to follow */ Index *pFirst; /* First of real indices on the table */ memset(&sPk, 0, sizeof(Index)); sPk.nKeyCol = 1; sPk.nColumn = 1; sPk.aiColumn = &aiColumnPk; sPk.aiRowLogEst = aiRowEstPk; sPk.onError = OE_Replace; sPk.pTable = pTab; sPk.szIdxRow = pTab->szTabRow; sPk.idxType = SQLITE_IDXTYPE_IPK; aiRowEstPk[0] = pTab->nRowLogEst; aiRowEstPk[1] = 0; pFirst = pSrc->pTab->pIndex; if( pSrc->fg.notIndexed==0 ){ /* The real indices of the table are only considered if the ** NOT INDEXED qualifier is omitted from the FROM clause */ sPk.pNext = pFirst; } pProbe = &sPk; } rSize = pTab->nRowLogEst; #ifndef SQLITE_OMIT_AUTOMATIC_INDEX /* Automatic indexes */ if( !pBuilder->pOrSet /* Not part of an OR optimization */ && (pWInfo->wctrlFlags & (WHERE_RIGHT_JOIN|WHERE_OR_SUBCLAUSE))==0 && (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0 && !pSrc->fg.isIndexedBy /* Has no INDEXED BY clause */ && !pSrc->fg.notIndexed /* Has no NOT INDEXED clause */ && HasRowid(pTab) /* Not WITHOUT ROWID table. (FIXME: Why not?) */ && !pSrc->fg.isCorrelated /* Not a correlated subquery */ && !pSrc->fg.isRecursive /* Not a recursive common table expression. */ && (pSrc->fg.jointype & JT_RIGHT)==0 /* Not the right tab of a RIGHT JOIN */ ){ /* Generate auto-index WhereLoops */ LogEst rLogSize; /* Logarithm of the number of rows in the table */ WhereTerm *pTerm; WhereTerm *pWCEnd = pWC->a + pWC->nTerm; rLogSize = estLog(rSize); for(pTerm=pWC->a; rc==SQLITE_OK && pTermprereqRight & pNew->maskSelf ) continue; if( termCanDriveIndex(pTerm, pSrc, 0) ){ pNew->u.btree.nEq = 1; pNew->nSkip = 0; pNew->u.btree.pIndex = 0; pNew->nLTerm = 1; pNew->aLTerm[0] = pTerm; /* TUNING: One-time cost for computing the automatic index is ** estimated to be X*N*log2(N) where N is the number of rows in ** the table being indexed and where X is 7 (LogEst=28) for normal ** tables or 0.5 (LogEst=-10) for views and subqueries. The value ** of X is smaller for views and subqueries so that the query planner ** will be more aggressive about generating automatic indexes for ** those objects, since there is no opportunity to add schema ** indexes on subqueries and views. */ pNew->rSetup = rLogSize + rSize; if( !IsView(pTab) && (pTab->tabFlags & TF_Ephemeral)==0 ){ pNew->rSetup += 28; }else{ pNew->rSetup -= 10; } ApplyCostMultiplier(pNew->rSetup, pTab->costMult); if( pNew->rSetup<0 ) pNew->rSetup = 0; /* TUNING: Each index lookup yields 20 rows in the table. This ** is more than the usual guess of 10 rows, since we have no way ** of knowing how selective the index will ultimately be. It would ** not be unreasonable to make this value much larger. */ pNew->nOut = 43; assert( 43==sqlite3LogEst(20) ); pNew->rRun = sqlite3LogEstAdd(rLogSize,pNew->nOut); pNew->wsFlags = WHERE_AUTO_INDEX; pNew->prereq = mPrereq | pTerm->prereqRight; rc = whereLoopInsert(pBuilder, pNew); } } } #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */ /* Loop over all indices. If there was an INDEXED BY clause, then only ** consider index pProbe. */ for(; rc==SQLITE_OK && pProbe; pProbe=(pSrc->fg.isIndexedBy ? 0 : pProbe->pNext), iSortIdx++ ){ if( pProbe->pPartIdxWhere!=0 && !whereUsablePartialIndex(pSrc->iCursor, pSrc->fg.jointype, pWC, pProbe->pPartIdxWhere) ){ testcase( pNew->iTab!=pSrc->iCursor ); /* See ticket [98d973b8f5] */ continue; /* Partial index inappropriate for this query */ } if( pProbe->bNoQuery ) continue; rSize = pProbe->aiRowLogEst[0]; pNew->u.btree.nEq = 0; pNew->u.btree.nBtm = 0; pNew->u.btree.nTop = 0; pNew->nSkip = 0; pNew->nLTerm = 0; pNew->iSortIdx = 0; pNew->rSetup = 0; pNew->prereq = mPrereq; pNew->nOut = rSize; pNew->u.btree.pIndex = pProbe; b = indexMightHelpWithOrderBy(pBuilder, pProbe, pSrc->iCursor); /* The ONEPASS_DESIRED flags never occurs together with ORDER BY */ assert( (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || b==0 ); if( pProbe->idxType==SQLITE_IDXTYPE_IPK ){ /* Integer primary key index */ pNew->wsFlags = WHERE_IPK; /* Full table scan */ pNew->iSortIdx = b ? iSortIdx : 0; /* TUNING: Cost of full table scan is 3.0*N. The 3.0 factor is an ** extra cost designed to discourage the use of full table scans, ** since index lookups have better worst-case performance if our ** stat guesses are wrong. Reduce the 3.0 penalty slightly ** (to 2.75) if we have valid STAT4 information for the table. ** At 2.75, a full table scan is preferred over using an index on ** a column with just two distinct values where each value has about ** an equal number of appearances. Without STAT4 data, we still want ** to use an index in that case, since the constraint might be for ** the scarcer of the two values, and in that case an index lookup is ** better. */ #ifdef SQLITE_ENABLE_STAT4 pNew->rRun = rSize + 16 - 2*((pTab->tabFlags & TF_HasStat4)!=0); #else pNew->rRun = rSize + 16; #endif if( IsView(pTab) || (pTab->tabFlags & TF_Ephemeral)!=0 ){ pNew->wsFlags |= WHERE_VIEWSCAN; } ApplyCostMultiplier(pNew->rRun, pTab->costMult); whereLoopOutputAdjust(pWC, pNew, rSize); rc = whereLoopInsert(pBuilder, pNew); pNew->nOut = rSize; if( rc ) break; }else{ Bitmask m; if( pProbe->isCovering ){ pNew->wsFlags = WHERE_IDX_ONLY | WHERE_INDEXED; m = 0; }else{ m = pSrc->colUsed & pProbe->colNotIdxed; if( m==TOPBIT ){ m = whereIsCoveringIndex(pWInfo, pProbe, pSrc->iCursor); } pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED; } /* Full scan via index */ if( b || !HasRowid(pTab) || pProbe->pPartIdxWhere!=0 || pSrc->fg.isIndexedBy || ( m==0 && pProbe->bUnordered==0 && (pProbe->szIdxRowszTabRow) && (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 && sqlite3GlobalConfig.bUseCis && OptimizationEnabled(pWInfo->pParse->db, SQLITE_CoverIdxScan) ) ){ pNew->iSortIdx = b ? iSortIdx : 0; /* The cost of visiting the index rows is N*K, where K is ** between 1.1 and 3.0, depending on the relative sizes of the ** index and table rows. */ pNew->rRun = rSize + 1 + (15*pProbe->szIdxRow)/pTab->szTabRow; if( m!=0 ){ /* If this is a non-covering index scan, add in the cost of ** doing table lookups. The cost will be 3x the number of ** lookups. Take into account WHERE clause terms that can be ** satisfied using just the index, and that do not require a ** table lookup. */ LogEst nLookup = rSize + 16; /* Base cost: N*3 */ int ii; int iCur = pSrc->iCursor; WhereClause *pWC2 = &pWInfo->sWC; for(ii=0; iinTerm; ii++){ WhereTerm *pTerm = &pWC2->a[ii]; if( !sqlite3ExprCoveredByIndex(pTerm->pExpr, iCur, pProbe) ){ break; } /* pTerm can be evaluated using just the index. So reduce ** the expected number of table lookups accordingly */ if( pTerm->truthProb<=0 ){ nLookup += pTerm->truthProb; }else{ nLookup--; if( pTerm->eOperator & (WO_EQ|WO_IS) ) nLookup -= 19; } } pNew->rRun = sqlite3LogEstAdd(pNew->rRun, nLookup); } ApplyCostMultiplier(pNew->rRun, pTab->costMult); whereLoopOutputAdjust(pWC, pNew, rSize); if( (pSrc->fg.jointype & JT_RIGHT)!=0 && pProbe->aColExpr ){ /* Do not do an SCAN of a index-on-expression in a RIGHT JOIN ** because the cursor used to access the index might not be ** positioned to the correct row during the right-join no-match ** loop. */ }else{ rc = whereLoopInsert(pBuilder, pNew); } pNew->nOut = rSize; if( rc ) break; } } pBuilder->bldFlags1 = 0; rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0); if( pBuilder->bldFlags1==SQLITE_BLDF1_INDEXED ){ /* If a non-unique index is used, or if a prefix of the key for ** unique index is used (making the index functionally non-unique) ** then the sqlite_stat1 data becomes important for scoring the ** plan */ pTab->tabFlags |= TF_StatsUsed; } #ifdef SQLITE_ENABLE_STAT4 sqlite3Stat4ProbeFree(pBuilder->pRec); pBuilder->nRecValid = 0; pBuilder->pRec = 0; #endif } return rc; } #ifndef SQLITE_OMIT_VIRTUALTABLE /* ** Return true if pTerm is a virtual table LIMIT or OFFSET term. */ static int isLimitTerm(WhereTerm *pTerm){ assert( pTerm->eOperator==WO_AUX || pTerm->eMatchOp==0 ); return pTerm->eMatchOp>=SQLITE_INDEX_CONSTRAINT_LIMIT && pTerm->eMatchOp<=SQLITE_INDEX_CONSTRAINT_OFFSET; } /* ** Argument pIdxInfo is already populated with all constraints that may ** be used by the virtual table identified by pBuilder->pNew->iTab. This ** function marks a subset of those constraints usable, invokes the ** xBestIndex method and adds the returned plan to pBuilder. ** ** A constraint is marked usable if: ** ** * Argument mUsable indicates that its prerequisites are available, and ** ** * It is not one of the operators specified in the mExclude mask passed ** as the fourth argument (which in practice is either WO_IN or 0). ** ** Argument mPrereq is a mask of tables that must be scanned before the ** virtual table in question. These are added to the plans prerequisites ** before it is added to pBuilder. ** ** Output parameter *pbIn is set to true if the plan added to pBuilder ** uses one or more WO_IN terms, or false otherwise. */ static int whereLoopAddVirtualOne( WhereLoopBuilder *pBuilder, Bitmask mPrereq, /* Mask of tables that must be used. */ Bitmask mUsable, /* Mask of usable tables */ u16 mExclude, /* Exclude terms using these operators */ sqlite3_index_info *pIdxInfo, /* Populated object for xBestIndex */ u16 mNoOmit, /* Do not omit these constraints */ int *pbIn, /* OUT: True if plan uses an IN(...) op */ int *pbRetryLimit /* OUT: Retry without LIMIT/OFFSET */ ){ WhereClause *pWC = pBuilder->pWC; HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; struct sqlite3_index_constraint *pIdxCons; struct sqlite3_index_constraint_usage *pUsage = pIdxInfo->aConstraintUsage; int i; int mxTerm; int rc = SQLITE_OK; WhereLoop *pNew = pBuilder->pNew; Parse *pParse = pBuilder->pWInfo->pParse; SrcItem *pSrc = &pBuilder->pWInfo->pTabList->a[pNew->iTab]; int nConstraint = pIdxInfo->nConstraint; assert( (mUsable & mPrereq)==mPrereq ); *pbIn = 0; pNew->prereq = mPrereq; /* Set the usable flag on the subset of constraints identified by ** arguments mUsable and mExclude. */ pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint; for(i=0; ia[pIdxCons->iTermOffset]; pIdxCons->usable = 0; if( (pTerm->prereqRight & mUsable)==pTerm->prereqRight && (pTerm->eOperator & mExclude)==0 && (pbRetryLimit || !isLimitTerm(pTerm)) ){ pIdxCons->usable = 1; } } /* Initialize the output fields of the sqlite3_index_info structure */ memset(pUsage, 0, sizeof(pUsage[0])*nConstraint); assert( pIdxInfo->needToFreeIdxStr==0 ); pIdxInfo->idxStr = 0; pIdxInfo->idxNum = 0; pIdxInfo->orderByConsumed = 0; pIdxInfo->estimatedCost = SQLITE_BIG_DBL / (double)2; pIdxInfo->estimatedRows = 25; pIdxInfo->idxFlags = 0; pIdxInfo->colUsed = (sqlite3_int64)pSrc->colUsed; pHidden->mHandleIn = 0; /* Invoke the virtual table xBestIndex() method */ rc = vtabBestIndex(pParse, pSrc->pTab, pIdxInfo); if( rc ){ if( rc==SQLITE_CONSTRAINT ){ /* If the xBestIndex method returns SQLITE_CONSTRAINT, that means ** that the particular combination of parameters provided is unusable. ** Make no entries in the loop table. */ WHERETRACE(0xffff, (" ^^^^--- non-viable plan rejected!\n")); return SQLITE_OK; } return rc; } mxTerm = -1; assert( pNew->nLSlot>=nConstraint ); memset(pNew->aLTerm, 0, sizeof(pNew->aLTerm[0])*nConstraint ); memset(&pNew->u.vtab, 0, sizeof(pNew->u.vtab)); pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint; for(i=0; i=0 ){ WhereTerm *pTerm; int j = pIdxCons->iTermOffset; if( iTerm>=nConstraint || j<0 || j>=pWC->nTerm || pNew->aLTerm[iTerm]!=0 || pIdxCons->usable==0 ){ sqlite3ErrorMsg(pParse,"%s.xBestIndex malfunction",pSrc->pTab->zName); testcase( pIdxInfo->needToFreeIdxStr ); return SQLITE_ERROR; } testcase( iTerm==nConstraint-1 ); testcase( j==0 ); testcase( j==pWC->nTerm-1 ); pTerm = &pWC->a[j]; pNew->prereq |= pTerm->prereqRight; assert( iTermnLSlot ); pNew->aLTerm[iTerm] = pTerm; if( iTerm>mxTerm ) mxTerm = iTerm; testcase( iTerm==15 ); testcase( iTerm==16 ); if( pUsage[i].omit ){ if( i<16 && ((1<u.vtab.omitMask |= 1<eMatchOp==SQLITE_INDEX_CONSTRAINT_OFFSET ){ pNew->u.vtab.bOmitOffset = 1; } } if( SMASKBIT32(i) & pHidden->mHandleIn ){ pNew->u.vtab.mHandleIn |= MASKBIT32(iTerm); }else if( (pTerm->eOperator & WO_IN)!=0 ){ /* A virtual table that is constrained by an IN clause may not ** consume the ORDER BY clause because (1) the order of IN terms ** is not necessarily related to the order of output terms and ** (2) Multiple outputs from a single IN value will not merge ** together. */ pIdxInfo->orderByConsumed = 0; pIdxInfo->idxFlags &= ~SQLITE_INDEX_SCAN_UNIQUE; *pbIn = 1; assert( (mExclude & WO_IN)==0 ); } assert( pbRetryLimit || !isLimitTerm(pTerm) ); if( isLimitTerm(pTerm) && *pbIn ){ /* If there is an IN(...) term handled as an == (separate call to ** xFilter for each value on the RHS of the IN) and a LIMIT or ** OFFSET term handled as well, the plan is unusable. Set output ** variable *pbRetryLimit to true to tell the caller to retry with ** LIMIT and OFFSET disabled. */ if( pIdxInfo->needToFreeIdxStr ){ sqlite3_free(pIdxInfo->idxStr); pIdxInfo->idxStr = 0; pIdxInfo->needToFreeIdxStr = 0; } *pbRetryLimit = 1; return SQLITE_OK; } } } pNew->nLTerm = mxTerm+1; for(i=0; i<=mxTerm; i++){ if( pNew->aLTerm[i]==0 ){ /* The non-zero argvIdx values must be contiguous. Raise an ** error if they are not */ sqlite3ErrorMsg(pParse,"%s.xBestIndex malfunction",pSrc->pTab->zName); testcase( pIdxInfo->needToFreeIdxStr ); return SQLITE_ERROR; } } assert( pNew->nLTerm<=pNew->nLSlot ); pNew->u.vtab.idxNum = pIdxInfo->idxNum; pNew->u.vtab.needFree = pIdxInfo->needToFreeIdxStr; pIdxInfo->needToFreeIdxStr = 0; pNew->u.vtab.idxStr = pIdxInfo->idxStr; pNew->u.vtab.isOrdered = (i8)(pIdxInfo->orderByConsumed ? pIdxInfo->nOrderBy : 0); pNew->rSetup = 0; pNew->rRun = sqlite3LogEstFromDouble(pIdxInfo->estimatedCost); pNew->nOut = sqlite3LogEst(pIdxInfo->estimatedRows); /* Set the WHERE_ONEROW flag if the xBestIndex() method indicated ** that the scan will visit at most one row. Clear it otherwise. */ if( pIdxInfo->idxFlags & SQLITE_INDEX_SCAN_UNIQUE ){ pNew->wsFlags |= WHERE_ONEROW; }else{ pNew->wsFlags &= ~WHERE_ONEROW; } rc = whereLoopInsert(pBuilder, pNew); if( pNew->u.vtab.needFree ){ sqlite3_free(pNew->u.vtab.idxStr); pNew->u.vtab.needFree = 0; } WHERETRACE(0xffff, (" bIn=%d prereqIn=%04llx prereqOut=%04llx\n", *pbIn, (sqlite3_uint64)mPrereq, (sqlite3_uint64)(pNew->prereq & ~mPrereq))); return rc; } /* ** Return the collating sequence for a constraint passed into xBestIndex. ** ** pIdxInfo must be an sqlite3_index_info structure passed into xBestIndex. ** This routine depends on there being a HiddenIndexInfo structure immediately ** following the sqlite3_index_info structure. ** ** Return a pointer to the collation name: ** ** 1. If there is an explicit COLLATE operator on the constaint, return it. ** ** 2. Else, if the column has an alternative collation, return that. ** ** 3. Otherwise, return "BINARY". */ const char *sqlite3_vtab_collation(sqlite3_index_info *pIdxInfo, int iCons){ HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; const char *zRet = 0; if( iCons>=0 && iConsnConstraint ){ CollSeq *pC = 0; int iTerm = pIdxInfo->aConstraint[iCons].iTermOffset; Expr *pX = pHidden->pWC->a[iTerm].pExpr; if( pX->pLeft ){ pC = sqlite3ExprCompareCollSeq(pHidden->pParse, pX); } zRet = (pC ? pC->zName : sqlite3StrBINARY); } return zRet; } /* ** Return true if constraint iCons is really an IN(...) constraint, or ** false otherwise. If iCons is an IN(...) constraint, set (if bHandle!=0) ** or clear (if bHandle==0) the flag to handle it using an iterator. */ int sqlite3_vtab_in(sqlite3_index_info *pIdxInfo, int iCons, int bHandle){ HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; u32 m = SMASKBIT32(iCons); if( m & pHidden->mIn ){ if( bHandle==0 ){ pHidden->mHandleIn &= ~m; }else if( bHandle>0 ){ pHidden->mHandleIn |= m; } return 1; } return 0; } /* ** This interface is callable from within the xBestIndex callback only. ** ** If possible, set (*ppVal) to point to an object containing the value ** on the right-hand-side of constraint iCons. */ int sqlite3_vtab_rhs_value( sqlite3_index_info *pIdxInfo, /* Copy of first argument to xBestIndex */ int iCons, /* Constraint for which RHS is wanted */ sqlite3_value **ppVal /* Write value extracted here */ ){ HiddenIndexInfo *pH = (HiddenIndexInfo*)&pIdxInfo[1]; sqlite3_value *pVal = 0; int rc = SQLITE_OK; if( iCons<0 || iCons>=pIdxInfo->nConstraint ){ rc = SQLITE_MISUSE; /* EV: R-30545-25046 */ }else{ if( pH->aRhs[iCons]==0 ){ WhereTerm *pTerm = &pH->pWC->a[pIdxInfo->aConstraint[iCons].iTermOffset]; rc = sqlite3ValueFromExpr( pH->pParse->db, pTerm->pExpr->pRight, ENC(pH->pParse->db), SQLITE_AFF_BLOB, &pH->aRhs[iCons] ); testcase( rc!=SQLITE_OK ); } pVal = pH->aRhs[iCons]; } *ppVal = pVal; if( rc==SQLITE_OK && pVal==0 ){ /* IMP: R-19933-32160 */ rc = SQLITE_NOTFOUND; /* IMP: R-36424-56542 */ } return rc; } /* ** Return true if ORDER BY clause may be handled as DISTINCT. */ int sqlite3_vtab_distinct(sqlite3_index_info *pIdxInfo){ HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; assert( pHidden->eDistinct>=0 && pHidden->eDistinct<=3 ); return pHidden->eDistinct; } #if (defined(SQLITE_ENABLE_DBPAGE_VTAB) || defined(SQLITE_TEST)) \ && !defined(SQLITE_OMIT_VIRTUALTABLE) /* ** Cause the prepared statement that is associated with a call to ** xBestIndex to potentiall use all schemas. If the statement being ** prepared is read-only, then just start read transactions on all ** schemas. But if this is a write operation, start writes on all ** schemas. ** ** This is used by the (built-in) sqlite_dbpage virtual table. */ void sqlite3VtabUsesAllSchemas(sqlite3_index_info *pIdxInfo){ HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; Parse *pParse = pHidden->pParse; int nDb = pParse->db->nDb; int i; for(i=0; iwriteMask ){ for(i=0; ipNew->iTab. That table is guaranteed to be a virtual table. ** ** If there are no LEFT or CROSS JOIN joins in the query, both mPrereq and ** mUnusable are set to 0. Otherwise, mPrereq is a mask of all FROM clause ** entries that occur before the virtual table in the FROM clause and are ** separated from it by at least one LEFT or CROSS JOIN. Similarly, the ** mUnusable mask contains all FROM clause entries that occur after the ** virtual table and are separated from it by at least one LEFT or ** CROSS JOIN. ** ** For example, if the query were: ** ** ... FROM t1, t2 LEFT JOIN t3, t4, vt CROSS JOIN t5, t6; ** ** then mPrereq corresponds to (t1, t2) and mUnusable to (t5, t6). ** ** All the tables in mPrereq must be scanned before the current virtual ** table. So any terms for which all prerequisites are satisfied by ** mPrereq may be specified as "usable" in all calls to xBestIndex. ** Conversely, all tables in mUnusable must be scanned after the current ** virtual table, so any terms for which the prerequisites overlap with ** mUnusable should always be configured as "not-usable" for xBestIndex. */ static int whereLoopAddVirtual( WhereLoopBuilder *pBuilder, /* WHERE clause information */ Bitmask mPrereq, /* Tables that must be scanned before this one */ Bitmask mUnusable /* Tables that must be scanned after this one */ ){ int rc = SQLITE_OK; /* Return code */ WhereInfo *pWInfo; /* WHERE analysis context */ Parse *pParse; /* The parsing context */ WhereClause *pWC; /* The WHERE clause */ SrcItem *pSrc; /* The FROM clause term to search */ sqlite3_index_info *p; /* Object to pass to xBestIndex() */ int nConstraint; /* Number of constraints in p */ int bIn; /* True if plan uses IN(...) operator */ WhereLoop *pNew; Bitmask mBest; /* Tables used by best possible plan */ u16 mNoOmit; int bRetry = 0; /* True to retry with LIMIT/OFFSET disabled */ assert( (mPrereq & mUnusable)==0 ); pWInfo = pBuilder->pWInfo; pParse = pWInfo->pParse; pWC = pBuilder->pWC; pNew = pBuilder->pNew; pSrc = &pWInfo->pTabList->a[pNew->iTab]; assert( IsVirtual(pSrc->pTab) ); p = allocateIndexInfo(pWInfo, pWC, mUnusable, pSrc, &mNoOmit); if( p==0 ) return SQLITE_NOMEM_BKPT; pNew->rSetup = 0; pNew->wsFlags = WHERE_VIRTUALTABLE; pNew->nLTerm = 0; pNew->u.vtab.needFree = 0; nConstraint = p->nConstraint; if( whereLoopResize(pParse->db, pNew, nConstraint) ){ freeIndexInfo(pParse->db, p); return SQLITE_NOMEM_BKPT; } /* First call xBestIndex() with all constraints usable. */ WHERETRACE(0x800, ("BEGIN %s.addVirtual()\n", pSrc->pTab->zName)); WHERETRACE(0x40, (" VirtualOne: all usable\n")); rc = whereLoopAddVirtualOne( pBuilder, mPrereq, ALLBITS, 0, p, mNoOmit, &bIn, &bRetry ); if( bRetry ){ assert( rc==SQLITE_OK ); rc = whereLoopAddVirtualOne( pBuilder, mPrereq, ALLBITS, 0, p, mNoOmit, &bIn, 0 ); } /* If the call to xBestIndex() with all terms enabled produced a plan ** that does not require any source tables (IOW: a plan with mBest==0) ** and does not use an IN(...) operator, then there is no point in making ** any further calls to xBestIndex() since they will all return the same ** result (if the xBestIndex() implementation is sane). */ if( rc==SQLITE_OK && ((mBest = (pNew->prereq & ~mPrereq))!=0 || bIn) ){ int seenZero = 0; /* True if a plan with no prereqs seen */ int seenZeroNoIN = 0; /* Plan with no prereqs and no IN(...) seen */ Bitmask mPrev = 0; Bitmask mBestNoIn = 0; /* If the plan produced by the earlier call uses an IN(...) term, call ** xBestIndex again, this time with IN(...) terms disabled. */ if( bIn ){ WHERETRACE(0x40, (" VirtualOne: all usable w/o IN\n")); rc = whereLoopAddVirtualOne( pBuilder, mPrereq, ALLBITS, WO_IN, p, mNoOmit, &bIn, 0); assert( bIn==0 ); mBestNoIn = pNew->prereq & ~mPrereq; if( mBestNoIn==0 ){ seenZero = 1; seenZeroNoIN = 1; } } /* Call xBestIndex once for each distinct value of (prereqRight & ~mPrereq) ** in the set of terms that apply to the current virtual table. */ while( rc==SQLITE_OK ){ int i; Bitmask mNext = ALLBITS; assert( mNext>0 ); for(i=0; ia[p->aConstraint[i].iTermOffset].prereqRight & ~mPrereq ); if( mThis>mPrev && mThisprereq==mPrereq ){ seenZero = 1; if( bIn==0 ) seenZeroNoIN = 1; } } /* If the calls to xBestIndex() in the above loop did not find a plan ** that requires no source tables at all (i.e. one guaranteed to be ** usable), make a call here with all source tables disabled */ if( rc==SQLITE_OK && seenZero==0 ){ WHERETRACE(0x40, (" VirtualOne: all disabled\n")); rc = whereLoopAddVirtualOne( pBuilder, mPrereq, mPrereq, 0, p, mNoOmit, &bIn, 0); if( bIn==0 ) seenZeroNoIN = 1; } /* If the calls to xBestIndex() have so far failed to find a plan ** that requires no source tables at all and does not use an IN(...) ** operator, make a final call to obtain one here. */ if( rc==SQLITE_OK && seenZeroNoIN==0 ){ WHERETRACE(0x40, (" VirtualOne: all disabled and w/o IN\n")); rc = whereLoopAddVirtualOne( pBuilder, mPrereq, mPrereq, WO_IN, p, mNoOmit, &bIn, 0); } } if( p->needToFreeIdxStr ) sqlite3_free(p->idxStr); freeIndexInfo(pParse->db, p); WHERETRACE(0x800, ("END %s.addVirtual(), rc=%d\n", pSrc->pTab->zName, rc)); return rc; } #endif /* SQLITE_OMIT_VIRTUALTABLE */ /* ** Add WhereLoop entries to handle OR terms. This works for either ** btrees or virtual tables. */ static int whereLoopAddOr( WhereLoopBuilder *pBuilder, Bitmask mPrereq, Bitmask mUnusable ){ WhereInfo *pWInfo = pBuilder->pWInfo; WhereClause *pWC; WhereLoop *pNew; WhereTerm *pTerm, *pWCEnd; int rc = SQLITE_OK; int iCur; WhereClause tempWC; WhereLoopBuilder sSubBuild; WhereOrSet sSum, sCur; SrcItem *pItem; pWC = pBuilder->pWC; pWCEnd = pWC->a + pWC->nTerm; pNew = pBuilder->pNew; memset(&sSum, 0, sizeof(sSum)); pItem = pWInfo->pTabList->a + pNew->iTab; iCur = pItem->iCursor; /* The multi-index OR optimization does not work for RIGHT and FULL JOIN */ if( pItem->fg.jointype & JT_RIGHT ) return SQLITE_OK; for(pTerm=pWC->a; pTermeOperator & WO_OR)!=0 && (pTerm->u.pOrInfo->indexable & pNew->maskSelf)!=0 ){ WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc; WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm]; WhereTerm *pOrTerm; int once = 1; int i, j; sSubBuild = *pBuilder; sSubBuild.pOrSet = &sCur; WHERETRACE(0x200, ("Begin processing OR-clause %p\n", pTerm)); for(pOrTerm=pOrWC->a; pOrTermeOperator & WO_AND)!=0 ){ sSubBuild.pWC = &pOrTerm->u.pAndInfo->wc; }else if( pOrTerm->leftCursor==iCur ){ tempWC.pWInfo = pWC->pWInfo; tempWC.pOuter = pWC; tempWC.op = TK_AND; tempWC.nTerm = 1; tempWC.nBase = 1; tempWC.a = pOrTerm; sSubBuild.pWC = &tempWC; }else{ continue; } sCur.n = 0; #ifdef WHERETRACE_ENABLED WHERETRACE(0x200, ("OR-term %d of %p has %d subterms:\n", (int)(pOrTerm-pOrWC->a), pTerm, sSubBuild.pWC->nTerm)); if( sqlite3WhereTrace & 0x400 ){ sqlite3WhereClausePrint(sSubBuild.pWC); } #endif #ifndef SQLITE_OMIT_VIRTUALTABLE if( IsVirtual(pItem->pTab) ){ rc = whereLoopAddVirtual(&sSubBuild, mPrereq, mUnusable); }else #endif { rc = whereLoopAddBtree(&sSubBuild, mPrereq); } if( rc==SQLITE_OK ){ rc = whereLoopAddOr(&sSubBuild, mPrereq, mUnusable); } assert( rc==SQLITE_OK || rc==SQLITE_DONE || sCur.n==0 || rc==SQLITE_NOMEM ); testcase( rc==SQLITE_NOMEM && sCur.n>0 ); testcase( rc==SQLITE_DONE ); if( sCur.n==0 ){ sSum.n = 0; break; }else if( once ){ whereOrMove(&sSum, &sCur); once = 0; }else{ WhereOrSet sPrev; whereOrMove(&sPrev, &sSum); sSum.n = 0; for(i=0; inLTerm = 1; pNew->aLTerm[0] = pTerm; pNew->wsFlags = WHERE_MULTI_OR; pNew->rSetup = 0; pNew->iSortIdx = 0; memset(&pNew->u, 0, sizeof(pNew->u)); for(i=0; rc==SQLITE_OK && irRun = sSum.a[i].rRun + 1; pNew->nOut = sSum.a[i].nOut; pNew->prereq = sSum.a[i].prereq; rc = whereLoopInsert(pBuilder, pNew); } WHERETRACE(0x200, ("End processing OR-clause %p\n", pTerm)); } } return rc; } /* ** Add all WhereLoop objects for all tables */ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){ WhereInfo *pWInfo = pBuilder->pWInfo; Bitmask mPrereq = 0; Bitmask mPrior = 0; int iTab; SrcList *pTabList = pWInfo->pTabList; SrcItem *pItem; SrcItem *pEnd = &pTabList->a[pWInfo->nLevel]; sqlite3 *db = pWInfo->pParse->db; int rc = SQLITE_OK; int bFirstPastRJ = 0; int hasRightJoin = 0; WhereLoop *pNew; /* Loop over the tables in the join, from left to right */ pNew = pBuilder->pNew; /* Verify that pNew has already been initialized */ assert( pNew->nLTerm==0 ); assert( pNew->wsFlags==0 ); assert( pNew->nLSlot>=ArraySize(pNew->aLTermSpace) ); assert( pNew->aLTerm!=0 ); pBuilder->iPlanLimit = SQLITE_QUERY_PLANNER_LIMIT; for(iTab=0, pItem=pTabList->a; pItemiTab = iTab; pBuilder->iPlanLimit += SQLITE_QUERY_PLANNER_LIMIT_INCR; pNew->maskSelf = sqlite3WhereGetMask(&pWInfo->sMaskSet, pItem->iCursor); if( bFirstPastRJ || (pItem->fg.jointype & (JT_OUTER|JT_CROSS|JT_LTORJ))!=0 ){ /* Add prerequisites to prevent reordering of FROM clause terms ** across CROSS joins and outer joins. The bFirstPastRJ boolean ** prevents the right operand of a RIGHT JOIN from being swapped with ** other elements even further to the right. ** ** The JT_LTORJ case and the hasRightJoin flag work together to ** prevent FROM-clause terms from moving from the right side of ** a LEFT JOIN over to the left side of that join if the LEFT JOIN ** is itself on the left side of a RIGHT JOIN. */ if( pItem->fg.jointype & JT_LTORJ ) hasRightJoin = 1; mPrereq |= mPrior; bFirstPastRJ = (pItem->fg.jointype & JT_RIGHT)!=0; }else if( !hasRightJoin ){ mPrereq = 0; } #ifndef SQLITE_OMIT_VIRTUALTABLE if( IsVirtual(pItem->pTab) ){ SrcItem *p; for(p=&pItem[1]; pfg.jointype & (JT_OUTER|JT_CROSS)) ){ mUnusable |= sqlite3WhereGetMask(&pWInfo->sMaskSet, p->iCursor); } } rc = whereLoopAddVirtual(pBuilder, mPrereq, mUnusable); }else #endif /* SQLITE_OMIT_VIRTUALTABLE */ { rc = whereLoopAddBtree(pBuilder, mPrereq); } if( rc==SQLITE_OK && pBuilder->pWC->hasOr ){ rc = whereLoopAddOr(pBuilder, mPrereq, mUnusable); } mPrior |= pNew->maskSelf; if( rc || db->mallocFailed ){ if( rc==SQLITE_DONE ){ /* We hit the query planner search limit set by iPlanLimit */ sqlite3_log(SQLITE_WARNING, "abbreviated query algorithm search"); rc = SQLITE_OK; }else{ break; } } } whereLoopClear(db, pNew); return rc; } /* ** Examine a WherePath (with the addition of the extra WhereLoop of the 6th ** parameters) to see if it outputs rows in the requested ORDER BY ** (or GROUP BY) without requiring a separate sort operation. Return N: ** ** N>0: N terms of the ORDER BY clause are satisfied ** N==0: No terms of the ORDER BY clause are satisfied ** N<0: Unknown yet how many terms of ORDER BY might be satisfied. ** ** Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as ** strict. With GROUP BY and DISTINCT the only requirement is that ** equivalent rows appear immediately adjacent to one another. GROUP BY ** and DISTINCT do not require rows to appear in any particular order as long ** as equivalent rows are grouped together. Thus for GROUP BY and DISTINCT ** the pOrderBy terms can be matched in any order. With ORDER BY, the ** pOrderBy terms must be matched in strict left-to-right order. */ static i8 wherePathSatisfiesOrderBy( WhereInfo *pWInfo, /* The WHERE clause */ ExprList *pOrderBy, /* ORDER BY or GROUP BY or DISTINCT clause to check */ WherePath *pPath, /* The WherePath to check */ u16 wctrlFlags, /* WHERE_GROUPBY or _DISTINCTBY or _ORDERBY_LIMIT */ u16 nLoop, /* Number of entries in pPath->aLoop[] */ WhereLoop *pLast, /* Add this WhereLoop to the end of pPath->aLoop[] */ Bitmask *pRevMask /* OUT: Mask of WhereLoops to run in reverse order */ ){ u8 revSet; /* True if rev is known */ u8 rev; /* Composite sort order */ u8 revIdx; /* Index sort order */ u8 isOrderDistinct; /* All prior WhereLoops are order-distinct */ u8 distinctColumns; /* True if the loop has UNIQUE NOT NULL columns */ u8 isMatch; /* iColumn matches a term of the ORDER BY clause */ u16 eqOpMask; /* Allowed equality operators */ u16 nKeyCol; /* Number of key columns in pIndex */ u16 nColumn; /* Total number of ordered columns in the index */ u16 nOrderBy; /* Number terms in the ORDER BY clause */ int iLoop; /* Index of WhereLoop in pPath being processed */ int i, j; /* Loop counters */ int iCur; /* Cursor number for current WhereLoop */ int iColumn; /* A column number within table iCur */ WhereLoop *pLoop = 0; /* Current WhereLoop being processed. */ WhereTerm *pTerm; /* A single term of the WHERE clause */ Expr *pOBExpr; /* An expression from the ORDER BY clause */ CollSeq *pColl; /* COLLATE function from an ORDER BY clause term */ Index *pIndex; /* The index associated with pLoop */ sqlite3 *db = pWInfo->pParse->db; /* Database connection */ Bitmask obSat = 0; /* Mask of ORDER BY terms satisfied so far */ Bitmask obDone; /* Mask of all ORDER BY terms */ Bitmask orderDistinctMask; /* Mask of all well-ordered loops */ Bitmask ready; /* Mask of inner loops */ /* ** We say the WhereLoop is "one-row" if it generates no more than one ** row of output. A WhereLoop is one-row if all of the following are true: ** (a) All index columns match with WHERE_COLUMN_EQ. ** (b) The index is unique ** Any WhereLoop with an WHERE_COLUMN_EQ constraint on the rowid is one-row. ** Every one-row WhereLoop will have the WHERE_ONEROW bit set in wsFlags. ** ** We say the WhereLoop is "order-distinct" if the set of columns from ** that WhereLoop that are in the ORDER BY clause are different for every ** row of the WhereLoop. Every one-row WhereLoop is automatically ** order-distinct. A WhereLoop that has no columns in the ORDER BY clause ** is not order-distinct. To be order-distinct is not quite the same as being ** UNIQUE since a UNIQUE column or index can have multiple rows that ** are NULL and NULL values are equivalent for the purpose of order-distinct. ** To be order-distinct, the columns must be UNIQUE and NOT NULL. ** ** The rowid for a table is always UNIQUE and NOT NULL so whenever the ** rowid appears in the ORDER BY clause, the corresponding WhereLoop is ** automatically order-distinct. */ assert( pOrderBy!=0 ); if( nLoop && OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ) return 0; nOrderBy = pOrderBy->nExpr; testcase( nOrderBy==BMS-1 ); if( nOrderBy>BMS-1 ) return 0; /* Cannot optimize overly large ORDER BYs */ isOrderDistinct = 1; obDone = MASKBIT(nOrderBy)-1; orderDistinctMask = 0; ready = 0; eqOpMask = WO_EQ | WO_IS | WO_ISNULL; if( wctrlFlags & (WHERE_ORDERBY_LIMIT|WHERE_ORDERBY_MAX|WHERE_ORDERBY_MIN) ){ eqOpMask |= WO_IN; } for(iLoop=0; isOrderDistinct && obSat0 ) ready |= pLoop->maskSelf; if( iLoopaLoop[iLoop]; if( wctrlFlags & WHERE_ORDERBY_LIMIT ) continue; }else{ pLoop = pLast; } if( pLoop->wsFlags & WHERE_VIRTUALTABLE ){ if( pLoop->u.vtab.isOrdered && ((wctrlFlags&(WHERE_DISTINCTBY|WHERE_SORTBYGROUP))!=WHERE_DISTINCTBY) ){ obSat = obDone; } break; }else if( wctrlFlags & WHERE_DISTINCTBY ){ pLoop->u.btree.nDistinctCol = 0; } iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor; /* Mark off any ORDER BY term X that is a column in the table of ** the current loop for which there is term in the WHERE ** clause of the form X IS NULL or X=? that reference only outer ** loops. */ for(i=0; ia[i].pExpr); if( NEVER(pOBExpr==0) ) continue; if( pOBExpr->op!=TK_COLUMN && pOBExpr->op!=TK_AGG_COLUMN ) continue; if( pOBExpr->iTable!=iCur ) continue; pTerm = sqlite3WhereFindTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn, ~ready, eqOpMask, 0); if( pTerm==0 ) continue; if( pTerm->eOperator==WO_IN ){ /* IN terms are only valid for sorting in the ORDER BY LIMIT ** optimization, and then only if they are actually used ** by the query plan */ assert( wctrlFlags & (WHERE_ORDERBY_LIMIT|WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX) ); for(j=0; jnLTerm && pTerm!=pLoop->aLTerm[j]; j++){} if( j>=pLoop->nLTerm ) continue; } if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){ Parse *pParse = pWInfo->pParse; CollSeq *pColl1 = sqlite3ExprNNCollSeq(pParse, pOrderBy->a[i].pExpr); CollSeq *pColl2 = sqlite3ExprCompareCollSeq(pParse, pTerm->pExpr); assert( pColl1 ); if( pColl2==0 || sqlite3StrICmp(pColl1->zName, pColl2->zName) ){ continue; } testcase( pTerm->pExpr->op==TK_IS ); } obSat |= MASKBIT(i); } if( (pLoop->wsFlags & WHERE_ONEROW)==0 ){ if( pLoop->wsFlags & WHERE_IPK ){ pIndex = 0; nKeyCol = 0; nColumn = 1; }else if( (pIndex = pLoop->u.btree.pIndex)==0 || pIndex->bUnordered ){ return 0; }else{ nKeyCol = pIndex->nKeyCol; nColumn = pIndex->nColumn; assert( nColumn==nKeyCol+1 || !HasRowid(pIndex->pTable) ); assert( pIndex->aiColumn[nColumn-1]==XN_ROWID || !HasRowid(pIndex->pTable)); /* All relevant terms of the index must also be non-NULL in order ** for isOrderDistinct to be true. So the isOrderDistint value ** computed here might be a false positive. Corrections will be ** made at tag-20210426-1 below */ isOrderDistinct = IsUniqueIndex(pIndex) && (pLoop->wsFlags & WHERE_SKIPSCAN)==0; } /* Loop through all columns of the index and deal with the ones ** that are not constrained by == or IN. */ rev = revSet = 0; distinctColumns = 0; for(j=0; j=pLoop->u.btree.nEq || (pLoop->aLTerm[j]==0)==(jnSkip) ); if( ju.btree.nEq && j>=pLoop->nSkip ){ u16 eOp = pLoop->aLTerm[j]->eOperator; /* Skip over == and IS and ISNULL terms. (Also skip IN terms when ** doing WHERE_ORDERBY_LIMIT processing). Except, IS and ISNULL ** terms imply that the index is not UNIQUE NOT NULL in which case ** the loop need to be marked as not order-distinct because it can ** have repeated NULL rows. ** ** If the current term is a column of an ((?,?) IN (SELECT...)) ** expression for which the SELECT returns more than one column, ** check that it is the only column used by this loop. Otherwise, ** if it is one of two or more, none of the columns can be ** considered to match an ORDER BY term. */ if( (eOp & eqOpMask)!=0 ){ if( eOp & (WO_ISNULL|WO_IS) ){ testcase( eOp & WO_ISNULL ); testcase( eOp & WO_IS ); testcase( isOrderDistinct ); isOrderDistinct = 0; } continue; }else if( ALWAYS(eOp & WO_IN) ){ /* ALWAYS() justification: eOp is an equality operator due to the ** ju.btree.nEq constraint above. Any equality other ** than WO_IN is captured by the previous "if". So this one ** always has to be WO_IN. */ Expr *pX = pLoop->aLTerm[j]->pExpr; for(i=j+1; iu.btree.nEq; i++){ if( pLoop->aLTerm[i]->pExpr==pX ){ assert( (pLoop->aLTerm[i]->eOperator & WO_IN) ); bOnce = 0; break; } } } } /* Get the column number in the table (iColumn) and sort order ** (revIdx) for the j-th column of the index. */ if( pIndex ){ iColumn = pIndex->aiColumn[j]; revIdx = pIndex->aSortOrder[j] & KEYINFO_ORDER_DESC; if( iColumn==pIndex->pTable->iPKey ) iColumn = XN_ROWID; }else{ iColumn = XN_ROWID; revIdx = 0; } /* An unconstrained column that might be NULL means that this ** WhereLoop is not well-ordered. tag-20210426-1 */ if( isOrderDistinct ){ if( iColumn>=0 && j>=pLoop->u.btree.nEq && pIndex->pTable->aCol[iColumn].notNull==0 ){ isOrderDistinct = 0; } if( iColumn==XN_EXPR ){ isOrderDistinct = 0; } } /* Find the ORDER BY term that corresponds to the j-th column ** of the index and mark that ORDER BY term off */ isMatch = 0; for(i=0; bOnce && ia[i].pExpr); testcase( wctrlFlags & WHERE_GROUPBY ); testcase( wctrlFlags & WHERE_DISTINCTBY ); if( NEVER(pOBExpr==0) ) continue; if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0; if( iColumn>=XN_ROWID ){ if( pOBExpr->op!=TK_COLUMN && pOBExpr->op!=TK_AGG_COLUMN ) continue; if( pOBExpr->iTable!=iCur ) continue; if( pOBExpr->iColumn!=iColumn ) continue; }else{ Expr *pIdxExpr = pIndex->aColExpr->a[j].pExpr; if( sqlite3ExprCompareSkip(pOBExpr, pIdxExpr, iCur) ){ continue; } } if( iColumn!=XN_ROWID ){ pColl = sqlite3ExprNNCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr); if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue; } if( wctrlFlags & WHERE_DISTINCTBY ){ pLoop->u.btree.nDistinctCol = j+1; } isMatch = 1; break; } if( isMatch && (wctrlFlags & WHERE_GROUPBY)==0 ){ /* Make sure the sort order is compatible in an ORDER BY clause. ** Sort order is irrelevant for a GROUP BY clause. */ if( revSet ){ if( (rev ^ revIdx) != (pOrderBy->a[i].fg.sortFlags&KEYINFO_ORDER_DESC) ){ isMatch = 0; } }else{ rev = revIdx ^ (pOrderBy->a[i].fg.sortFlags & KEYINFO_ORDER_DESC); if( rev ) *pRevMask |= MASKBIT(iLoop); revSet = 1; } } if( isMatch && (pOrderBy->a[i].fg.sortFlags & KEYINFO_ORDER_BIGNULL) ){ if( j==pLoop->u.btree.nEq ){ pLoop->wsFlags |= WHERE_BIGNULL_SORT; }else{ isMatch = 0; } } if( isMatch ){ if( iColumn==XN_ROWID ){ testcase( distinctColumns==0 ); distinctColumns = 1; } obSat |= MASKBIT(i); }else{ /* No match found */ if( j==0 || jmaskSelf; for(i=0; ia[i].pExpr; mTerm = sqlite3WhereExprUsage(&pWInfo->sMaskSet,p); if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue; if( (mTerm&~orderDistinctMask)==0 ){ obSat |= MASKBIT(i); } } } } /* End the loop over all WhereLoops from outer-most down to inner-most */ if( obSat==obDone ) return (i8)nOrderBy; if( !isOrderDistinct ){ for(i=nOrderBy-1; i>0; i--){ Bitmask m = ALWAYS(iwctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY) ); assert( pWInfo->wctrlFlags & WHERE_SORTBYGROUP ); return pWInfo->sorted; } #ifdef WHERETRACE_ENABLED /* For debugging use only: */ static const char *wherePathName(WherePath *pPath, int nLoop, WhereLoop *pLast){ static char zName[65]; int i; for(i=0; iaLoop[i]->cId; } if( pLast ) zName[i++] = pLast->cId; zName[i] = 0; return zName; } #endif /* ** Return the cost of sorting nRow rows, assuming that the keys have ** nOrderby columns and that the first nSorted columns are already in ** order. */ static LogEst whereSortingCost( WhereInfo *pWInfo, LogEst nRow, int nOrderBy, int nSorted ){ /* TUNING: Estimated cost of a full external sort, where N is ** the number of rows to sort is: ** ** cost = (3.0 * N * log(N)). ** ** Or, if the order-by clause has X terms but only the last Y ** terms are out of order, then block-sorting will reduce the ** sorting cost to: ** ** cost = (3.0 * N * log(N)) * (Y/X) ** ** The (Y/X) term is implemented using stack variable rScale ** below. */ LogEst rScale, rSortCost; assert( nOrderBy>0 && 66==sqlite3LogEst(100) ); rScale = sqlite3LogEst((nOrderBy-nSorted)*100/nOrderBy) - 66; rSortCost = nRow + rScale + 16; /* Multiple by log(M) where M is the number of output rows. ** Use the LIMIT for M if it is smaller. Or if this sort is for ** a DISTINCT operator, M will be the number of distinct output ** rows, so fudge it downwards a bit. */ if( (pWInfo->wctrlFlags & WHERE_USE_LIMIT)!=0 && pWInfo->iLimitiLimit; }else if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT) ){ /* TUNING: In the sort for a DISTINCT operator, assume that the DISTINCT ** reduces the number of output rows by a factor of 2 */ if( nRow>10 ){ nRow -= 10; assert( 10==sqlite3LogEst(2) ); } } rSortCost += estLog(nRow); return rSortCost; } /* ** Given the list of WhereLoop objects at pWInfo->pLoops, this routine ** attempts to find the lowest cost path that visits each WhereLoop ** once. This path is then loaded into the pWInfo->a[].pWLoop fields. ** ** Assume that the total number of output rows that will need to be sorted ** will be nRowEst (in the 10*log2 representation). Or, ignore sorting ** costs if nRowEst==0. ** ** Return SQLITE_OK on success or SQLITE_NOMEM of a memory allocation ** error occurs. */ static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){ int mxChoice; /* Maximum number of simultaneous paths tracked */ int nLoop; /* Number of terms in the join */ Parse *pParse; /* Parsing context */ int iLoop; /* Loop counter over the terms of the join */ int ii, jj; /* Loop counters */ int mxI = 0; /* Index of next entry to replace */ int nOrderBy; /* Number of ORDER BY clause terms */ LogEst mxCost = 0; /* Maximum cost of a set of paths */ LogEst mxUnsorted = 0; /* Maximum unsorted cost of a set of path */ int nTo, nFrom; /* Number of valid entries in aTo[] and aFrom[] */ WherePath *aFrom; /* All nFrom paths at the previous level */ WherePath *aTo; /* The nTo best paths at the current level */ WherePath *pFrom; /* An element of aFrom[] that we are working on */ WherePath *pTo; /* An element of aTo[] that we are working on */ WhereLoop *pWLoop; /* One of the WhereLoop objects */ WhereLoop **pX; /* Used to divy up the pSpace memory */ LogEst *aSortCost = 0; /* Sorting and partial sorting costs */ char *pSpace; /* Temporary memory used by this routine */ int nSpace; /* Bytes of space allocated at pSpace */ pParse = pWInfo->pParse; nLoop = pWInfo->nLevel; /* TUNING: For simple queries, only the best path is tracked. ** For 2-way joins, the 5 best paths are followed. ** For joins of 3 or more tables, track the 10 best paths */ mxChoice = (nLoop<=1) ? 1 : (nLoop==2 ? 5 : 10); assert( nLoop<=pWInfo->pTabList->nSrc ); WHERETRACE(0x002, ("---- begin solver. (nRowEst=%d)\n", nRowEst)); /* If nRowEst is zero and there is an ORDER BY clause, ignore it. In this ** case the purpose of this call is to estimate the number of rows returned ** by the overall query. Once this estimate has been obtained, the caller ** will invoke this function a second time, passing the estimate as the ** nRowEst parameter. */ if( pWInfo->pOrderBy==0 || nRowEst==0 ){ nOrderBy = 0; }else{ nOrderBy = pWInfo->pOrderBy->nExpr; } /* Allocate and initialize space for aTo, aFrom and aSortCost[] */ nSpace = (sizeof(WherePath)+sizeof(WhereLoop*)*nLoop)*mxChoice*2; nSpace += sizeof(LogEst) * nOrderBy; pSpace = sqlite3StackAllocRawNN(pParse->db, nSpace); if( pSpace==0 ) return SQLITE_NOMEM_BKPT; aTo = (WherePath*)pSpace; aFrom = aTo+mxChoice; memset(aFrom, 0, sizeof(aFrom[0])); pX = (WhereLoop**)(aFrom+mxChoice); for(ii=mxChoice*2, pFrom=aTo; ii>0; ii--, pFrom++, pX += nLoop){ pFrom->aLoop = pX; } if( nOrderBy ){ /* If there is an ORDER BY clause and it is not being ignored, set up ** space for the aSortCost[] array. Each element of the aSortCost array ** is either zero - meaning it has not yet been initialized - or the ** cost of sorting nRowEst rows of data where the first X terms of ** the ORDER BY clause are already in order, where X is the array ** index. */ aSortCost = (LogEst*)pX; memset(aSortCost, 0, sizeof(LogEst) * nOrderBy); } assert( aSortCost==0 || &pSpace[nSpace]==(char*)&aSortCost[nOrderBy] ); assert( aSortCost!=0 || &pSpace[nSpace]==(char*)pX ); /* Seed the search with a single WherePath containing zero WhereLoops. ** ** TUNING: Do not let the number of iterations go above 28. If the cost ** of computing an automatic index is not paid back within the first 28 ** rows, then do not use the automatic index. */ aFrom[0].nRow = MIN(pParse->nQueryLoop, 48); assert( 48==sqlite3LogEst(28) ); nFrom = 1; assert( aFrom[0].isOrdered==0 ); if( nOrderBy ){ /* If nLoop is zero, then there are no FROM terms in the query. Since ** in this case the query may return a maximum of one row, the results ** are already in the requested order. Set isOrdered to nOrderBy to ** indicate this. Or, if nLoop is greater than zero, set isOrdered to ** -1, indicating that the result set may or may not be ordered, ** depending on the loops added to the current plan. */ aFrom[0].isOrdered = nLoop>0 ? -1 : nOrderBy; } /* Compute successively longer WherePaths using the previous generation ** of WherePaths as the basis for the next. Keep track of the mxChoice ** best paths at each generation */ for(iLoop=0; iLooppLoops; pWLoop; pWLoop=pWLoop->pNextLoop){ LogEst nOut; /* Rows visited by (pFrom+pWLoop) */ LogEst rCost; /* Cost of path (pFrom+pWLoop) */ LogEst rUnsorted; /* Unsorted cost of (pFrom+pWLoop) */ i8 isOrdered; /* isOrdered for (pFrom+pWLoop) */ Bitmask maskNew; /* Mask of src visited by (..) */ Bitmask revMask; /* Mask of rev-order loops for (..) */ if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue; if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) continue; if( (pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 && pFrom->nRow<3 ){ /* Do not use an automatic index if the this loop is expected ** to run less than 1.25 times. It is tempting to also exclude ** automatic index usage on an outer loop, but sometimes an automatic ** index is useful in the outer loop of a correlated subquery. */ assert( 10==sqlite3LogEst(2) ); continue; } /* At this point, pWLoop is a candidate to be the next loop. ** Compute its cost */ rUnsorted = sqlite3LogEstAdd(pWLoop->rSetup,pWLoop->rRun + pFrom->nRow); rUnsorted = sqlite3LogEstAdd(rUnsorted, pFrom->rUnsorted); nOut = pFrom->nRow + pWLoop->nOut; maskNew = pFrom->maskLoop | pWLoop->maskSelf; isOrdered = pFrom->isOrdered; if( isOrdered<0 ){ revMask = 0; isOrdered = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags, iLoop, pWLoop, &revMask); }else{ revMask = pFrom->revLoop; } if( isOrdered>=0 && isOrderedwsFlags & WHERE_VIEWSCAN)!=0 ){ rCost += -10; nOut += -30; } /* Check to see if pWLoop should be added to the set of ** mxChoice best-so-far paths. ** ** First look for an existing path among best-so-far paths ** that covers the same set of loops and has the same isOrdered ** setting as the current path candidate. ** ** The term "((pTo->isOrdered^isOrdered)&0x80)==0" is equivalent ** to (pTo->isOrdered==(-1))==(isOrdered==(-1))" for the range ** of legal values for isOrdered, -1..64. */ for(jj=0, pTo=aTo; jjmaskLoop==maskNew && ((pTo->isOrdered^isOrdered)&0x80)==0 ){ testcase( jj==nTo-1 ); break; } } if( jj>=nTo ){ /* None of the existing best-so-far paths match the candidate. */ if( nTo>=mxChoice && (rCost>mxCost || (rCost==mxCost && rUnsorted>=mxUnsorted)) ){ /* The current candidate is no better than any of the mxChoice ** paths currently in the best-so-far buffer. So discard ** this candidate as not viable. */ #ifdef WHERETRACE_ENABLED /* 0x4 */ if( sqlite3WhereTrace&0x4 ){ sqlite3DebugPrintf("Skip %s cost=%-3d,%3d,%3d order=%c\n", wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted, isOrdered>=0 ? isOrdered+'0' : '?'); } #endif continue; } /* If we reach this points it means that the new candidate path ** needs to be added to the set of best-so-far paths. */ if( nTo=0 ? isOrdered+'0' : '?'); } #endif }else{ /* Control reaches here if best-so-far path pTo=aTo[jj] covers the ** same set of loops and has the same isOrdered setting as the ** candidate path. Check to see if the candidate should replace ** pTo or if the candidate should be skipped. ** ** The conditional is an expanded vector comparison equivalent to: ** (pTo->rCost,pTo->nRow,pTo->rUnsorted) <= (rCost,nOut,rUnsorted) */ if( pTo->rCostrCost==rCost && (pTo->nRownRow==nOut && pTo->rUnsorted<=rUnsorted) ) ) ){ #ifdef WHERETRACE_ENABLED /* 0x4 */ if( sqlite3WhereTrace&0x4 ){ sqlite3DebugPrintf( "Skip %s cost=%-3d,%3d,%3d order=%c", wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted, isOrdered>=0 ? isOrdered+'0' : '?'); sqlite3DebugPrintf(" vs %s cost=%-3d,%3d,%3d order=%c\n", wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow, pTo->rUnsorted, pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?'); } #endif /* Discard the candidate path from further consideration */ testcase( pTo->rCost==rCost ); continue; } testcase( pTo->rCost==rCost+1 ); /* Control reaches here if the candidate path is better than the ** pTo path. Replace pTo with the candidate. */ #ifdef WHERETRACE_ENABLED /* 0x4 */ if( sqlite3WhereTrace&0x4 ){ sqlite3DebugPrintf( "Update %s cost=%-3d,%3d,%3d order=%c", wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted, isOrdered>=0 ? isOrdered+'0' : '?'); sqlite3DebugPrintf(" was %s cost=%-3d,%3d,%3d order=%c\n", wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow, pTo->rUnsorted, pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?'); } #endif } /* pWLoop is a winner. Add it to the set of best so far */ pTo->maskLoop = pFrom->maskLoop | pWLoop->maskSelf; pTo->revLoop = revMask; pTo->nRow = nOut; pTo->rCost = rCost; pTo->rUnsorted = rUnsorted; pTo->isOrdered = isOrdered; memcpy(pTo->aLoop, pFrom->aLoop, sizeof(WhereLoop*)*iLoop); pTo->aLoop[iLoop] = pWLoop; if( nTo>=mxChoice ){ mxI = 0; mxCost = aTo[0].rCost; mxUnsorted = aTo[0].nRow; for(jj=1, pTo=&aTo[1]; jjrCost>mxCost || (pTo->rCost==mxCost && pTo->rUnsorted>mxUnsorted) ){ mxCost = pTo->rCost; mxUnsorted = pTo->rUnsorted; mxI = jj; } } } } } #ifdef WHERETRACE_ENABLED /* >=2 */ if( sqlite3WhereTrace & 0x02 ){ sqlite3DebugPrintf("---- after round %d ----\n", iLoop); for(ii=0, pTo=aTo; iirCost, pTo->nRow, pTo->isOrdered>=0 ? (pTo->isOrdered+'0') : '?'); if( pTo->isOrdered>0 ){ sqlite3DebugPrintf(" rev=0x%llx\n", pTo->revLoop); }else{ sqlite3DebugPrintf("\n"); } } } #endif /* Swap the roles of aFrom and aTo for the next generation */ pFrom = aTo; aTo = aFrom; aFrom = pFrom; nFrom = nTo; } if( nFrom==0 ){ sqlite3ErrorMsg(pParse, "no query solution"); sqlite3StackFreeNN(pParse->db, pSpace); return SQLITE_ERROR; } /* Find the lowest cost path. pFrom will be left pointing to that path */ pFrom = aFrom; for(ii=1; iirCost>aFrom[ii].rCost ) pFrom = &aFrom[ii]; } assert( pWInfo->nLevel==nLoop ); /* Load the lowest cost path into pWInfo */ for(iLoop=0; iLoopa + iLoop; pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop]; pLevel->iFrom = pWLoop->iTab; pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor; } if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)!=0 && (pWInfo->wctrlFlags & WHERE_DISTINCTBY)==0 && pWInfo->eDistinct==WHERE_DISTINCT_NOOP && nRowEst ){ Bitmask notUsed; int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pResultSet, pFrom, WHERE_DISTINCTBY, nLoop-1, pFrom->aLoop[nLoop-1], ¬Used); if( rc==pWInfo->pResultSet->nExpr ){ pWInfo->eDistinct = WHERE_DISTINCT_ORDERED; } } pWInfo->bOrderedInnerLoop = 0; if( pWInfo->pOrderBy ){ pWInfo->nOBSat = pFrom->isOrdered; if( pWInfo->wctrlFlags & WHERE_DISTINCTBY ){ if( pFrom->isOrdered==pWInfo->pOrderBy->nExpr ){ pWInfo->eDistinct = WHERE_DISTINCT_ORDERED; } }else{ pWInfo->revMask = pFrom->revLoop; if( pWInfo->nOBSat<=0 ){ pWInfo->nOBSat = 0; if( nLoop>0 ){ u32 wsFlags = pFrom->aLoop[nLoop-1]->wsFlags; if( (wsFlags & WHERE_ONEROW)==0 && (wsFlags&(WHERE_IPK|WHERE_COLUMN_IN))!=(WHERE_IPK|WHERE_COLUMN_IN) ){ Bitmask m = 0; int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, pFrom, WHERE_ORDERBY_LIMIT, nLoop-1, pFrom->aLoop[nLoop-1], &m); testcase( wsFlags & WHERE_IPK ); testcase( wsFlags & WHERE_COLUMN_IN ); if( rc==pWInfo->pOrderBy->nExpr ){ pWInfo->bOrderedInnerLoop = 1; pWInfo->revMask = m; } } } }else if( nLoop && pWInfo->nOBSat==1 && (pWInfo->wctrlFlags & (WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX))!=0 ){ pWInfo->bOrderedInnerLoop = 1; } } if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP) && pWInfo->nOBSat==pWInfo->pOrderBy->nExpr && nLoop>0 ){ Bitmask revMask = 0; int nOrder = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, pFrom, 0, nLoop-1, pFrom->aLoop[nLoop-1], &revMask ); assert( pWInfo->sorted==0 ); if( nOrder==pWInfo->pOrderBy->nExpr ){ pWInfo->sorted = 1; pWInfo->revMask = revMask; } } } pWInfo->nRowOut = pFrom->nRow; /* Free temporary memory and return success */ sqlite3StackFreeNN(pParse->db, pSpace); return SQLITE_OK; } /* ** Most queries use only a single table (they are not joins) and have ** simple == constraints against indexed fields. This routine attempts ** to plan those simple cases using much less ceremony than the ** general-purpose query planner, and thereby yield faster sqlite3_prepare() ** times for the common case. ** ** Return non-zero on success, if this query can be handled by this ** no-frills query planner. Return zero if this query needs the ** general-purpose query planner. */ static int whereShortCut(WhereLoopBuilder *pBuilder){ WhereInfo *pWInfo; SrcItem *pItem; WhereClause *pWC; WhereTerm *pTerm; WhereLoop *pLoop; int iCur; int j; Table *pTab; Index *pIdx; WhereScan scan; pWInfo = pBuilder->pWInfo; if( pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE ) return 0; assert( pWInfo->pTabList->nSrc>=1 ); pItem = pWInfo->pTabList->a; pTab = pItem->pTab; if( IsVirtual(pTab) ) return 0; if( pItem->fg.isIndexedBy || pItem->fg.notIndexed ){ testcase( pItem->fg.isIndexedBy ); testcase( pItem->fg.notIndexed ); return 0; } iCur = pItem->iCursor; pWC = &pWInfo->sWC; pLoop = pBuilder->pNew; pLoop->wsFlags = 0; pLoop->nSkip = 0; pTerm = whereScanInit(&scan, pWC, iCur, -1, WO_EQ|WO_IS, 0); while( pTerm && pTerm->prereqRight ) pTerm = whereScanNext(&scan); if( pTerm ){ testcase( pTerm->eOperator & WO_IS ); pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW; pLoop->aLTerm[0] = pTerm; pLoop->nLTerm = 1; pLoop->u.btree.nEq = 1; /* TUNING: Cost of a rowid lookup is 10 */ pLoop->rRun = 33; /* 33==sqlite3LogEst(10) */ }else{ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ int opMask; assert( pLoop->aLTermSpace==pLoop->aLTerm ); if( !IsUniqueIndex(pIdx) || pIdx->pPartIdxWhere!=0 || pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace) ) continue; opMask = pIdx->uniqNotNull ? (WO_EQ|WO_IS) : WO_EQ; for(j=0; jnKeyCol; j++){ pTerm = whereScanInit(&scan, pWC, iCur, j, opMask, pIdx); while( pTerm && pTerm->prereqRight ) pTerm = whereScanNext(&scan); if( pTerm==0 ) break; testcase( pTerm->eOperator & WO_IS ); pLoop->aLTerm[j] = pTerm; } if( j!=pIdx->nKeyCol ) continue; pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED; if( pIdx->isCovering || (pItem->colUsed & pIdx->colNotIdxed)==0 ){ pLoop->wsFlags |= WHERE_IDX_ONLY; } pLoop->nLTerm = j; pLoop->u.btree.nEq = j; pLoop->u.btree.pIndex = pIdx; /* TUNING: Cost of a unique index lookup is 15 */ pLoop->rRun = 39; /* 39==sqlite3LogEst(15) */ break; } } if( pLoop->wsFlags ){ pLoop->nOut = (LogEst)1; pWInfo->a[0].pWLoop = pLoop; assert( pWInfo->sMaskSet.n==1 && iCur==pWInfo->sMaskSet.ix[0] ); pLoop->maskSelf = 1; /* sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur); */ pWInfo->a[0].iTabCur = iCur; pWInfo->nRowOut = 1; if( pWInfo->pOrderBy ) pWInfo->nOBSat = pWInfo->pOrderBy->nExpr; if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){ pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE; } if( scan.iEquiv>1 ) pLoop->wsFlags |= WHERE_TRANSCONS; #ifdef SQLITE_DEBUG pLoop->cId = '0'; #endif #ifdef WHERETRACE_ENABLED if( sqlite3WhereTrace ){ sqlite3DebugPrintf("whereShortCut() used to compute solution\n"); } #endif return 1; } return 0; } /* ** Helper function for exprIsDeterministic(). */ static int exprNodeIsDeterministic(Walker *pWalker, Expr *pExpr){ if( pExpr->op==TK_FUNCTION && ExprHasProperty(pExpr, EP_ConstFunc)==0 ){ pWalker->eCode = 0; return WRC_Abort; } return WRC_Continue; } /* ** Return true if the expression contains no non-deterministic SQL ** functions. Do not consider non-deterministic SQL functions that are ** part of sub-select statements. */ static int exprIsDeterministic(Expr *p){ Walker w; memset(&w, 0, sizeof(w)); w.eCode = 1; w.xExprCallback = exprNodeIsDeterministic; w.xSelectCallback = sqlite3SelectWalkFail; sqlite3WalkExpr(&w, p); return w.eCode; } #ifdef WHERETRACE_ENABLED /* ** Display all WhereLoops in pWInfo */ static void showAllWhereLoops(WhereInfo *pWInfo, WhereClause *pWC){ if( sqlite3WhereTrace ){ /* Display all of the WhereLoop objects */ WhereLoop *p; int i; static const char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz" "ABCDEFGHIJKLMNOPQRSTUVWYXZ"; for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){ p->cId = zLabel[i%(sizeof(zLabel)-1)]; sqlite3WhereLoopPrint(p, pWC); } } } # define WHERETRACE_ALL_LOOPS(W,C) showAllWhereLoops(W,C) #else # define WHERETRACE_ALL_LOOPS(W,C) #endif /* Attempt to omit tables from a join that do not affect the result. ** For a table to not affect the result, the following must be true: ** ** 1) The query must not be an aggregate. ** 2) The table must be the RHS of a LEFT JOIN. ** 3) Either the query must be DISTINCT, or else the ON or USING clause ** must contain a constraint that limits the scan of the table to ** at most a single row. ** 4) The table must not be referenced by any part of the query apart ** from its own USING or ON clause. ** ** For example, given: ** ** CREATE TABLE t1(ipk INTEGER PRIMARY KEY, v1); ** CREATE TABLE t2(ipk INTEGER PRIMARY KEY, v2); ** CREATE TABLE t3(ipk INTEGER PRIMARY KEY, v3); ** ** then table t2 can be omitted from the following: ** ** SELECT v1, v3 FROM t1 ** LEFT JOIN t2 ON (t1.ipk=t2.ipk) ** LEFT JOIN t3 ON (t1.ipk=t3.ipk) ** ** or from: ** ** SELECT DISTINCT v1, v3 FROM t1 ** LEFT JOIN t2 ** LEFT JOIN t3 ON (t1.ipk=t3.ipk) */ static SQLITE_NOINLINE Bitmask whereOmitNoopJoin( WhereInfo *pWInfo, Bitmask notReady ){ int i; Bitmask tabUsed; /* Preconditions checked by the caller */ assert( pWInfo->nLevel>=2 ); assert( OptimizationEnabled(pWInfo->pParse->db, SQLITE_OmitNoopJoin) ); /* These two preconditions checked by the caller combine to guarantee ** condition (1) of the header comment */ assert( pWInfo->pResultSet!=0 ); assert( 0==(pWInfo->wctrlFlags & WHERE_AGG_DISTINCT) ); tabUsed = sqlite3WhereExprListUsage(&pWInfo->sMaskSet, pWInfo->pResultSet); if( pWInfo->pOrderBy ){ tabUsed |= sqlite3WhereExprListUsage(&pWInfo->sMaskSet, pWInfo->pOrderBy); } for(i=pWInfo->nLevel-1; i>=1; i--){ WhereTerm *pTerm, *pEnd; SrcItem *pItem; WhereLoop *pLoop; pLoop = pWInfo->a[i].pWLoop; pItem = &pWInfo->pTabList->a[pLoop->iTab]; if( (pItem->fg.jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ) continue; if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)==0 && (pLoop->wsFlags & WHERE_ONEROW)==0 ){ continue; } if( (tabUsed & pLoop->maskSelf)!=0 ) continue; pEnd = pWInfo->sWC.a + pWInfo->sWC.nTerm; for(pTerm=pWInfo->sWC.a; pTermprereqAll & pLoop->maskSelf)!=0 ){ if( !ExprHasProperty(pTerm->pExpr, EP_OuterON) || pTerm->pExpr->w.iJoin!=pItem->iCursor ){ break; } } } if( pTerm drop loop %c not used\n", pLoop->cId)); notReady &= ~pLoop->maskSelf; for(pTerm=pWInfo->sWC.a; pTermprereqAll & pLoop->maskSelf)!=0 ){ pTerm->wtFlags |= TERM_CODED; } } if( i!=pWInfo->nLevel-1 ){ int nByte = (pWInfo->nLevel-1-i) * sizeof(WhereLevel); memmove(&pWInfo->a[i], &pWInfo->a[i+1], nByte); } pWInfo->nLevel--; assert( pWInfo->nLevel>0 ); } return notReady; } /* ** Check to see if there are any SEARCH loops that might benefit from ** using a Bloom filter. Consider a Bloom filter if: ** ** (1) The SEARCH happens more than N times where N is the number ** of rows in the table that is being considered for the Bloom ** filter. ** (2) Some searches are expected to find zero rows. (This is determined ** by the WHERE_SELFCULL flag on the term.) ** (3) Bloom-filter processing is not disabled. (Checked by the ** caller.) ** (4) The size of the table being searched is known by ANALYZE. ** ** This block of code merely checks to see if a Bloom filter would be ** appropriate, and if so sets the WHERE_BLOOMFILTER flag on the ** WhereLoop. The implementation of the Bloom filter comes further ** down where the code for each WhereLoop is generated. */ static SQLITE_NOINLINE void whereCheckIfBloomFilterIsUseful( const WhereInfo *pWInfo ){ int i; LogEst nSearch; assert( pWInfo->nLevel>=2 ); assert( OptimizationEnabled(pWInfo->pParse->db, SQLITE_BloomFilter) ); nSearch = pWInfo->a[0].pWLoop->nOut; for(i=1; inLevel; i++){ WhereLoop *pLoop = pWInfo->a[i].pWLoop; const unsigned int reqFlags = (WHERE_SELFCULL|WHERE_COLUMN_EQ); if( (pLoop->wsFlags & reqFlags)==reqFlags /* vvvvvv--- Always the case if WHERE_COLUMN_EQ is defined */ && ALWAYS((pLoop->wsFlags & (WHERE_IPK|WHERE_INDEXED))!=0) ){ SrcItem *pItem = &pWInfo->pTabList->a[pLoop->iTab]; Table *pTab = pItem->pTab; pTab->tabFlags |= TF_StatsUsed; if( nSearch > pTab->nRowLogEst && (pTab->tabFlags & TF_HasStat1)!=0 ){ testcase( pItem->fg.jointype & JT_LEFT ); pLoop->wsFlags |= WHERE_BLOOMFILTER; pLoop->wsFlags &= ~WHERE_IDX_ONLY; WHERETRACE(0xffff, ( "-> use Bloom-filter on loop %c because there are ~%.1e " "lookups into %s which has only ~%.1e rows\n", pLoop->cId, (double)sqlite3LogEstToInt(nSearch), pTab->zName, (double)sqlite3LogEstToInt(pTab->nRowLogEst))); } } nSearch += pLoop->nOut; } } /* ** This is an sqlite3ParserAddCleanup() callback that is invoked to ** free the Parse->pIdxExpr list when the Parse object is destroyed. */ static void whereIndexedExprCleanup(sqlite3 *db, void *pObject){ Parse *pParse = (Parse*)pObject; while( pParse->pIdxExpr!=0 ){ IndexedExpr *p = pParse->pIdxExpr; pParse->pIdxExpr = p->pIENext; sqlite3ExprDelete(db, p->pExpr); sqlite3DbFreeNN(db, p); } } /* ** The index pIdx is used by a query and contains one or more expressions. ** In other words pIdx is an index on an expression. iIdxCur is the cursor ** number for the index and iDataCur is the cursor number for the corresponding ** table. ** ** This routine adds IndexedExpr entries to the Parse->pIdxExpr field for ** each of the expressions in the index so that the expression code generator ** will know to replace occurrences of the indexed expression with ** references to the corresponding column of the index. */ static SQLITE_NOINLINE void whereAddIndexedExpr( Parse *pParse, /* Add IndexedExpr entries to pParse->pIdxExpr */ Index *pIdx, /* The index-on-expression that contains the expressions */ int iIdxCur, /* Cursor number for pIdx */ SrcItem *pTabItem /* The FROM clause entry for the table */ ){ int i; IndexedExpr *p; Table *pTab; assert( pIdx->bHasExpr ); pTab = pIdx->pTable; for(i=0; inColumn; i++){ Expr *pExpr; int j = pIdx->aiColumn[i]; int bMaybeNullRow; if( j==XN_EXPR ){ pExpr = pIdx->aColExpr->a[i].pExpr; testcase( pTabItem->fg.jointype & JT_LEFT ); testcase( pTabItem->fg.jointype & JT_RIGHT ); testcase( pTabItem->fg.jointype & JT_LTORJ ); bMaybeNullRow = (pTabItem->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0; }else if( j>=0 && (pTab->aCol[j].colFlags & COLFLAG_VIRTUAL)!=0 ){ pExpr = sqlite3ColumnExpr(pTab, &pTab->aCol[j]); bMaybeNullRow = 0; }else{ continue; } if( sqlite3ExprIsConstant(pExpr) ) continue; p = sqlite3DbMallocRaw(pParse->db, sizeof(IndexedExpr)); if( p==0 ) break; p->pIENext = pParse->pIdxExpr; p->pExpr = sqlite3ExprDup(pParse->db, pExpr, 0); p->iDataCur = pTabItem->iCursor; p->iIdxCur = iIdxCur; p->iIdxCol = i; p->bMaybeNullRow = bMaybeNullRow; #ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS p->zIdxName = pIdx->zName; #endif pParse->pIdxExpr = p; if( p->pIENext==0 ){ sqlite3ParserAddCleanup(pParse, whereIndexedExprCleanup, pParse); } } } /* ** Generate the beginning of the loop used for WHERE clause processing. ** The return value is a pointer to an opaque structure that contains ** information needed to terminate the loop. Later, the calling routine ** should invoke sqlite3WhereEnd() with the return value of this function ** in order to complete the WHERE clause processing. ** ** If an error occurs, this routine returns NULL. ** ** The basic idea is to do a nested loop, one loop for each table in ** the FROM clause of a select. (INSERT and UPDATE statements are the ** same as a SELECT with only a single table in the FROM clause.) For ** example, if the SQL is this: ** ** SELECT * FROM t1, t2, t3 WHERE ...; ** ** Then the code generated is conceptually like the following: ** ** foreach row1 in t1 do \ Code generated ** foreach row2 in t2 do |-- by sqlite3WhereBegin() ** foreach row3 in t3 do / ** ... ** end \ Code generated ** end |-- by sqlite3WhereEnd() ** end / ** ** Note that the loops might not be nested in the order in which they ** appear in the FROM clause if a different order is better able to make ** use of indices. Note also that when the IN operator appears in ** the WHERE clause, it might result in additional nested loops for ** scanning through all values on the right-hand side of the IN. ** ** There are Btree cursors associated with each table. t1 uses cursor ** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor. ** And so forth. This routine generates code to open those VDBE cursors ** and sqlite3WhereEnd() generates the code to close them. ** ** The code that sqlite3WhereBegin() generates leaves the cursors named ** in pTabList pointing at their appropriate entries. The [...] code ** can use OP_Column and OP_Rowid opcodes on these cursors to extract ** data from the various tables of the loop. ** ** If the WHERE clause is empty, the foreach loops must each scan their ** entire tables. Thus a three-way join is an O(N^3) operation. But if ** the tables have indices and there are terms in the WHERE clause that ** refer to those indices, a complete table scan can be avoided and the ** code will run much faster. Most of the work of this routine is checking ** to see if there are indices that can be used to speed up the loop. ** ** Terms of the WHERE clause are also used to limit which rows actually ** make it to the "..." in the middle of the loop. After each "foreach", ** terms of the WHERE clause that use only terms in that loop and outer ** loops are evaluated and if false a jump is made around all subsequent ** inner loops (or around the "..." if the test occurs within the inner- ** most loop) ** ** OUTER JOINS ** ** An outer join of tables t1 and t2 is conceptally coded as follows: ** ** foreach row1 in t1 do ** flag = 0 ** foreach row2 in t2 do ** start: ** ... ** flag = 1 ** end ** if flag==0 then ** move the row2 cursor to a null row ** goto start ** fi ** end ** ** ORDER BY CLAUSE PROCESSING ** ** pOrderBy is a pointer to the ORDER BY clause (or the GROUP BY clause ** if the WHERE_GROUPBY flag is set in wctrlFlags) of a SELECT statement ** if there is one. If there is no ORDER BY clause or if this routine ** is called from an UPDATE or DELETE statement, then pOrderBy is NULL. ** ** The iIdxCur parameter is the cursor number of an index. If ** WHERE_OR_SUBCLAUSE is set, iIdxCur is the cursor number of an index ** to use for OR clause processing. The WHERE clause should use this ** specific cursor. If WHERE_ONEPASS_DESIRED is set, then iIdxCur is ** the first cursor in an array of cursors for all indices. iIdxCur should ** be used to compute the appropriate cursor depending on which index is ** used. */ WhereInfo *sqlite3WhereBegin( Parse *pParse, /* The parser context */ SrcList *pTabList, /* FROM clause: A list of all tables to be scanned */ Expr *pWhere, /* The WHERE clause */ ExprList *pOrderBy, /* An ORDER BY (or GROUP BY) clause, or NULL */ ExprList *pResultSet, /* Query result set. Req'd for DISTINCT */ Select *pSelect, /* The entire SELECT statement */ u16 wctrlFlags, /* The WHERE_* flags defined in sqliteInt.h */ int iAuxArg /* If WHERE_OR_SUBCLAUSE is set, index cursor number ** If WHERE_USE_LIMIT, then the limit amount */ ){ int nByteWInfo; /* Num. bytes allocated for WhereInfo struct */ int nTabList; /* Number of elements in pTabList */ WhereInfo *pWInfo; /* Will become the return value of this function */ Vdbe *v = pParse->pVdbe; /* The virtual database engine */ Bitmask notReady; /* Cursors that are not yet positioned */ WhereLoopBuilder sWLB; /* The WhereLoop builder */ WhereMaskSet *pMaskSet; /* The expression mask set */ WhereLevel *pLevel; /* A single level in pWInfo->a[] */ WhereLoop *pLoop; /* Pointer to a single WhereLoop object */ int ii; /* Loop counter */ sqlite3 *db; /* Database connection */ int rc; /* Return code */ u8 bFordelete = 0; /* OPFLAG_FORDELETE or zero, as appropriate */ assert( (wctrlFlags & WHERE_ONEPASS_MULTIROW)==0 || ( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 && (wctrlFlags & WHERE_OR_SUBCLAUSE)==0 )); /* Only one of WHERE_OR_SUBCLAUSE or WHERE_USE_LIMIT */ assert( (wctrlFlags & WHERE_OR_SUBCLAUSE)==0 || (wctrlFlags & WHERE_USE_LIMIT)==0 ); /* Variable initialization */ db = pParse->db; memset(&sWLB, 0, sizeof(sWLB)); /* An ORDER/GROUP BY clause of more than 63 terms cannot be optimized */ testcase( pOrderBy && pOrderBy->nExpr==BMS-1 ); if( pOrderBy && pOrderBy->nExpr>=BMS ) pOrderBy = 0; /* The number of tables in the FROM clause is limited by the number of ** bits in a Bitmask */ testcase( pTabList->nSrc==BMS ); if( pTabList->nSrc>BMS ){ sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS); return 0; } /* This function normally generates a nested loop for all tables in ** pTabList. But if the WHERE_OR_SUBCLAUSE flag is set, then we should ** only generate code for the first table in pTabList and assume that ** any cursors associated with subsequent tables are uninitialized. */ nTabList = (wctrlFlags & WHERE_OR_SUBCLAUSE) ? 1 : pTabList->nSrc; /* Allocate and initialize the WhereInfo structure that will become the ** return value. A single allocation is used to store the WhereInfo ** struct, the contents of WhereInfo.a[], the WhereClause structure ** and the WhereMaskSet structure. Since WhereClause contains an 8-byte ** field (type Bitmask) it must be aligned on an 8-byte boundary on ** some architectures. Hence the ROUND8() below. */ nByteWInfo = ROUND8P(sizeof(WhereInfo)+(nTabList-1)*sizeof(WhereLevel)); pWInfo = sqlite3DbMallocRawNN(db, nByteWInfo + sizeof(WhereLoop)); if( db->mallocFailed ){ sqlite3DbFree(db, pWInfo); pWInfo = 0; goto whereBeginError; } pWInfo->pParse = pParse; pWInfo->pTabList = pTabList; pWInfo->pOrderBy = pOrderBy; #if WHERETRACE_ENABLED pWInfo->pWhere = pWhere; #endif pWInfo->pResultSet = pResultSet; pWInfo->aiCurOnePass[0] = pWInfo->aiCurOnePass[1] = -1; pWInfo->nLevel = nTabList; pWInfo->iBreak = pWInfo->iContinue = sqlite3VdbeMakeLabel(pParse); pWInfo->wctrlFlags = wctrlFlags; pWInfo->iLimit = iAuxArg; pWInfo->savedNQueryLoop = pParse->nQueryLoop; pWInfo->pSelect = pSelect; memset(&pWInfo->nOBSat, 0, offsetof(WhereInfo,sWC) - offsetof(WhereInfo,nOBSat)); memset(&pWInfo->a[0], 0, sizeof(WhereLoop)+nTabList*sizeof(WhereLevel)); assert( pWInfo->eOnePass==ONEPASS_OFF ); /* ONEPASS defaults to OFF */ pMaskSet = &pWInfo->sMaskSet; pMaskSet->n = 0; pMaskSet->ix[0] = -99; /* Initialize ix[0] to a value that can never be ** a valid cursor number, to avoid an initial ** test for pMaskSet->n==0 in sqlite3WhereGetMask() */ sWLB.pWInfo = pWInfo; sWLB.pWC = &pWInfo->sWC; sWLB.pNew = (WhereLoop*)(((char*)pWInfo)+nByteWInfo); assert( EIGHT_BYTE_ALIGNMENT(sWLB.pNew) ); whereLoopInit(sWLB.pNew); #ifdef SQLITE_DEBUG sWLB.pNew->cId = '*'; #endif /* Split the WHERE clause into separate subexpressions where each ** subexpression is separated by an AND operator. */ sqlite3WhereClauseInit(&pWInfo->sWC, pWInfo); sqlite3WhereSplit(&pWInfo->sWC, pWhere, TK_AND); /* Special case: No FROM clause */ if( nTabList==0 ){ if( pOrderBy ) pWInfo->nOBSat = pOrderBy->nExpr; if( (wctrlFlags & WHERE_WANT_DISTINCT)!=0 && OptimizationEnabled(db, SQLITE_DistinctOpt) ){ pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE; } ExplainQueryPlan((pParse, 0, "SCAN CONSTANT ROW")); }else{ /* Assign a bit from the bitmask to every term in the FROM clause. ** ** The N-th term of the FROM clause is assigned a bitmask of 1<nSrc tables in ** pTabList, not just the first nTabList tables. nTabList is normally ** equal to pTabList->nSrc but might be shortened to 1 if the ** WHERE_OR_SUBCLAUSE flag is set. */ ii = 0; do{ createMask(pMaskSet, pTabList->a[ii].iCursor); sqlite3WhereTabFuncArgs(pParse, &pTabList->a[ii], &pWInfo->sWC); }while( (++ii)nSrc ); #ifdef SQLITE_DEBUG { Bitmask mx = 0; for(ii=0; iinSrc; ii++){ Bitmask m = sqlite3WhereGetMask(pMaskSet, pTabList->a[ii].iCursor); assert( m>=mx ); mx = m; } } #endif } /* Analyze all of the subexpressions. */ sqlite3WhereExprAnalyze(pTabList, &pWInfo->sWC); if( pSelect && pSelect->pLimit ){ sqlite3WhereAddLimit(&pWInfo->sWC, pSelect); } if( pParse->nErr ) goto whereBeginError; /* Special case: WHERE terms that do not refer to any tables in the join ** (constant expressions). Evaluate each such term, and jump over all the ** generated code if the result is not true. ** ** Do not do this if the expression contains non-deterministic functions ** that are not within a sub-select. This is not strictly required, but ** preserves SQLite's legacy behaviour in the following two cases: ** ** FROM ... WHERE random()>0; -- eval random() once per row ** FROM ... WHERE (SELECT random())>0; -- eval random() once overall */ for(ii=0; iinBase; ii++){ WhereTerm *pT = &sWLB.pWC->a[ii]; if( pT->wtFlags & TERM_VIRTUAL ) continue; if( pT->prereqAll==0 && (nTabList==0 || exprIsDeterministic(pT->pExpr)) ){ sqlite3ExprIfFalse(pParse, pT->pExpr, pWInfo->iBreak, SQLITE_JUMPIFNULL); pT->wtFlags |= TERM_CODED; } } if( wctrlFlags & WHERE_WANT_DISTINCT ){ if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){ /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */ wctrlFlags &= ~WHERE_WANT_DISTINCT; pWInfo->wctrlFlags &= ~WHERE_WANT_DISTINCT; }else if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){ /* The DISTINCT marking is pointless. Ignore it. */ pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE; }else if( pOrderBy==0 ){ /* Try to ORDER BY the result set to make distinct processing easier */ pWInfo->wctrlFlags |= WHERE_DISTINCTBY; pWInfo->pOrderBy = pResultSet; } } /* Construct the WhereLoop objects */ #if defined(WHERETRACE_ENABLED) if( sqlite3WhereTrace & 0xffff ){ sqlite3DebugPrintf("*** Optimizer Start *** (wctrlFlags: 0x%x",wctrlFlags); if( wctrlFlags & WHERE_USE_LIMIT ){ sqlite3DebugPrintf(", limit: %d", iAuxArg); } sqlite3DebugPrintf(")\n"); if( sqlite3WhereTrace & 0x100 ){ Select sSelect; memset(&sSelect, 0, sizeof(sSelect)); sSelect.selFlags = SF_WhereBegin; sSelect.pSrc = pTabList; sSelect.pWhere = pWhere; sSelect.pOrderBy = pOrderBy; sSelect.pEList = pResultSet; sqlite3TreeViewSelect(0, &sSelect, 0); } } if( sqlite3WhereTrace & 0x100 ){ /* Display all terms of the WHERE clause */ sqlite3DebugPrintf("---- WHERE clause at start of analysis:\n"); sqlite3WhereClausePrint(sWLB.pWC); } #endif if( nTabList!=1 || whereShortCut(&sWLB)==0 ){ rc = whereLoopAddAll(&sWLB); if( rc ) goto whereBeginError; #ifdef SQLITE_ENABLE_STAT4 /* If one or more WhereTerm.truthProb values were used in estimating ** loop parameters, but then those truthProb values were subsequently ** changed based on STAT4 information while computing subsequent loops, ** then we need to rerun the whole loop building process so that all ** loops will be built using the revised truthProb values. */ if( sWLB.bldFlags2 & SQLITE_BLDF2_2NDPASS ){ WHERETRACE_ALL_LOOPS(pWInfo, sWLB.pWC); WHERETRACE(0xffff, ("**** Redo all loop computations due to" " TERM_HIGHTRUTH changes ****\n")); while( pWInfo->pLoops ){ WhereLoop *p = pWInfo->pLoops; pWInfo->pLoops = p->pNextLoop; whereLoopDelete(db, p); } rc = whereLoopAddAll(&sWLB); if( rc ) goto whereBeginError; } #endif WHERETRACE_ALL_LOOPS(pWInfo, sWLB.pWC); wherePathSolver(pWInfo, 0); if( db->mallocFailed ) goto whereBeginError; if( pWInfo->pOrderBy ){ wherePathSolver(pWInfo, pWInfo->nRowOut+1); if( db->mallocFailed ) goto whereBeginError; } } if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){ pWInfo->revMask = ALLBITS; } if( pParse->nErr ){ goto whereBeginError; } assert( db->mallocFailed==0 ); #ifdef WHERETRACE_ENABLED if( sqlite3WhereTrace ){ sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo->nRowOut); if( pWInfo->nOBSat>0 ){ sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo->nOBSat, pWInfo->revMask); } switch( pWInfo->eDistinct ){ case WHERE_DISTINCT_UNIQUE: { sqlite3DebugPrintf(" DISTINCT=unique"); break; } case WHERE_DISTINCT_ORDERED: { sqlite3DebugPrintf(" DISTINCT=ordered"); break; } case WHERE_DISTINCT_UNORDERED: { sqlite3DebugPrintf(" DISTINCT=unordered"); break; } } sqlite3DebugPrintf("\n"); for(ii=0; iinLevel; ii++){ sqlite3WhereLoopPrint(pWInfo->a[ii].pWLoop, sWLB.pWC); } } #endif /* Attempt to omit tables from a join that do not affect the result. ** See the comment on whereOmitNoopJoin() for further information. ** ** This query optimization is factored out into a separate "no-inline" ** procedure to keep the sqlite3WhereBegin() procedure from becoming ** too large. If sqlite3WhereBegin() becomes too large, that prevents ** some C-compiler optimizers from in-lining the ** sqlite3WhereCodeOneLoopStart() procedure, and it is important to ** in-line sqlite3WhereCodeOneLoopStart() for performance reasons. */ notReady = ~(Bitmask)0; if( pWInfo->nLevel>=2 && pResultSet!=0 /* these two combine to guarantee */ && 0==(wctrlFlags & WHERE_AGG_DISTINCT) /* condition (1) above */ && OptimizationEnabled(db, SQLITE_OmitNoopJoin) ){ notReady = whereOmitNoopJoin(pWInfo, notReady); nTabList = pWInfo->nLevel; assert( nTabList>0 ); } /* Check to see if there are any SEARCH loops that might benefit from ** using a Bloom filter. */ if( pWInfo->nLevel>=2 && OptimizationEnabled(db, SQLITE_BloomFilter) ){ whereCheckIfBloomFilterIsUseful(pWInfo); } #if defined(WHERETRACE_ENABLED) if( sqlite3WhereTrace & 0x100 ){ /* Display all terms of the WHERE clause */ sqlite3DebugPrintf("---- WHERE clause at end of analysis:\n"); sqlite3WhereClausePrint(sWLB.pWC); } WHERETRACE(0xffff,("*** Optimizer Finished ***\n")); #endif pWInfo->pParse->nQueryLoop += pWInfo->nRowOut; /* If the caller is an UPDATE or DELETE statement that is requesting ** to use a one-pass algorithm, determine if this is appropriate. ** ** A one-pass approach can be used if the caller has requested one ** and either (a) the scan visits at most one row or (b) each ** of the following are true: ** ** * the caller has indicated that a one-pass approach can be used ** with multiple rows (by setting WHERE_ONEPASS_MULTIROW), and ** * the table is not a virtual table, and ** * either the scan does not use the OR optimization or the caller ** is a DELETE operation (WHERE_DUPLICATES_OK is only specified ** for DELETE). ** ** The last qualification is because an UPDATE statement uses ** WhereInfo.aiCurOnePass[1] to determine whether or not it really can ** use a one-pass approach, and this is not set accurately for scans ** that use the OR optimization. */ assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 ); if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 ){ int wsFlags = pWInfo->a[0].pWLoop->wsFlags; int bOnerow = (wsFlags & WHERE_ONEROW)!=0; assert( !(wsFlags & WHERE_VIRTUALTABLE) || IsVirtual(pTabList->a[0].pTab) ); if( bOnerow || ( 0!=(wctrlFlags & WHERE_ONEPASS_MULTIROW) && !IsVirtual(pTabList->a[0].pTab) && (0==(wsFlags & WHERE_MULTI_OR) || (wctrlFlags & WHERE_DUPLICATES_OK)) )){ pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI; if( HasRowid(pTabList->a[0].pTab) && (wsFlags & WHERE_IDX_ONLY) ){ if( wctrlFlags & WHERE_ONEPASS_MULTIROW ){ bFordelete = OPFLAG_FORDELETE; } pWInfo->a[0].pWLoop->wsFlags = (wsFlags & ~WHERE_IDX_ONLY); } } } /* Open all tables in the pTabList and any indices selected for ** searching those tables. */ for(ii=0, pLevel=pWInfo->a; iia[pLevel->iFrom]; pTab = pTabItem->pTab; iDb = sqlite3SchemaToIndex(db, pTab->pSchema); pLoop = pLevel->pWLoop; if( (pTab->tabFlags & TF_Ephemeral)!=0 || IsView(pTab) ){ /* Do nothing */ }else #ifndef SQLITE_OMIT_VIRTUALTABLE if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){ const char *pVTab = (const char *)sqlite3GetVTable(db, pTab); int iCur = pTabItem->iCursor; sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0, pVTab, P4_VTAB); }else if( IsVirtual(pTab) ){ /* noop */ }else #endif if( ((pLoop->wsFlags & WHERE_IDX_ONLY)==0 && (wctrlFlags & WHERE_OR_SUBCLAUSE)==0) || (pTabItem->fg.jointype & (JT_LTORJ|JT_RIGHT))!=0 ){ int op = OP_OpenRead; if( pWInfo->eOnePass!=ONEPASS_OFF ){ op = OP_OpenWrite; pWInfo->aiCurOnePass[0] = pTabItem->iCursor; }; sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op); assert( pTabItem->iCursor==pLevel->iTabCur ); testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS-1 ); testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS ); if( pWInfo->eOnePass==ONEPASS_OFF && pTab->nColtabFlags & (TF_HasGenerated|TF_WithoutRowid))==0 && (pLoop->wsFlags & (WHERE_AUTO_INDEX|WHERE_BLOOMFILTER))==0 ){ /* If we know that only a prefix of the record will be used, ** it is advantageous to reduce the "column count" field in ** the P4 operand of the OP_OpenRead/Write opcode. */ Bitmask b = pTabItem->colUsed; int n = 0; for(; b; b=b>>1, n++){} sqlite3VdbeChangeP4(v, -1, SQLITE_INT_TO_PTR(n), P4_INT32); assert( n<=pTab->nCol ); } #ifdef SQLITE_ENABLE_CURSOR_HINTS if( pLoop->u.btree.pIndex!=0 ){ sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ|bFordelete); }else #endif { sqlite3VdbeChangeP5(v, bFordelete); } #ifdef SQLITE_ENABLE_COLUMN_USED_MASK sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, pTabItem->iCursor, 0, 0, (const u8*)&pTabItem->colUsed, P4_INT64); #endif }else{ sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName); } if( pLoop->wsFlags & WHERE_INDEXED ){ Index *pIx = pLoop->u.btree.pIndex; int iIndexCur; int op = OP_OpenRead; /* iAuxArg is always set to a positive value if ONEPASS is possible */ assert( iAuxArg!=0 || (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 ); if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIx) && (wctrlFlags & WHERE_OR_SUBCLAUSE)!=0 ){ /* This is one term of an OR-optimization using the PRIMARY KEY of a ** WITHOUT ROWID table. No need for a separate index */ iIndexCur = pLevel->iTabCur; op = 0; }else if( pWInfo->eOnePass!=ONEPASS_OFF ){ Index *pJ = pTabItem->pTab->pIndex; iIndexCur = iAuxArg; assert( wctrlFlags & WHERE_ONEPASS_DESIRED ); while( ALWAYS(pJ) && pJ!=pIx ){ iIndexCur++; pJ = pJ->pNext; } op = OP_OpenWrite; pWInfo->aiCurOnePass[1] = iIndexCur; }else if( iAuxArg && (wctrlFlags & WHERE_OR_SUBCLAUSE)!=0 ){ iIndexCur = iAuxArg; op = OP_ReopenIdx; }else{ iIndexCur = pParse->nTab++; if( pIx->bHasExpr && OptimizationEnabled(db, SQLITE_IndexedExpr) ){ whereAddIndexedExpr(pParse, pIx, iIndexCur, pTabItem); } } pLevel->iIdxCur = iIndexCur; assert( pIx!=0 ); assert( pIx->pSchema==pTab->pSchema ); assert( iIndexCur>=0 ); if( op ){ sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb); sqlite3VdbeSetP4KeyInfo(pParse, pIx); if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0 && (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0 && (pLoop->wsFlags & WHERE_BIGNULL_SORT)==0 && (pLoop->wsFlags & WHERE_IN_SEEKSCAN)==0 && (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0 && pWInfo->eDistinct!=WHERE_DISTINCT_ORDERED ){ sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); } VdbeComment((v, "%s", pIx->zName)); #ifdef SQLITE_ENABLE_COLUMN_USED_MASK { u64 colUsed = 0; int ii, jj; for(ii=0; iinColumn; ii++){ jj = pIx->aiColumn[ii]; if( jj<0 ) continue; if( jj>63 ) jj = 63; if( (pTabItem->colUsed & MASKBIT(jj))==0 ) continue; colUsed |= ((u64)1)<<(ii<63 ? ii : 63); } sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, iIndexCur, 0, 0, (u8*)&colUsed, P4_INT64); } #endif /* SQLITE_ENABLE_COLUMN_USED_MASK */ } } if( iDb>=0 ) sqlite3CodeVerifySchema(pParse, iDb); if( (pTabItem->fg.jointype & JT_RIGHT)!=0 && (pLevel->pRJ = sqlite3WhereMalloc(pWInfo, sizeof(WhereRightJoin)))!=0 ){ WhereRightJoin *pRJ = pLevel->pRJ; pRJ->iMatch = pParse->nTab++; pRJ->regBloom = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Blob, 65536, pRJ->regBloom); pRJ->regReturn = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Null, 0, pRJ->regReturn); assert( pTab==pTabItem->pTab ); if( HasRowid(pTab) ){ KeyInfo *pInfo; sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pRJ->iMatch, 1); pInfo = sqlite3KeyInfoAlloc(pParse->db, 1, 0); if( pInfo ){ pInfo->aColl[0] = 0; pInfo->aSortFlags[0] = 0; sqlite3VdbeAppendP4(v, pInfo, P4_KEYINFO); } }else{ Index *pPk = sqlite3PrimaryKeyIndex(pTab); sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pRJ->iMatch, pPk->nKeyCol); sqlite3VdbeSetP4KeyInfo(pParse, pPk); } pLoop->wsFlags &= ~WHERE_IDX_ONLY; /* The nature of RIGHT JOIN processing is such that it messes up ** the output order. So omit any ORDER BY/GROUP BY elimination ** optimizations. We need to do an actual sort for RIGHT JOIN. */ pWInfo->nOBSat = 0; pWInfo->eDistinct = WHERE_DISTINCT_UNORDERED; } } pWInfo->iTop = sqlite3VdbeCurrentAddr(v); if( db->mallocFailed ) goto whereBeginError; /* Generate the code to do the search. Each iteration of the for ** loop below generates code for a single nested loop of the VM ** program. */ for(ii=0; iinErr ) goto whereBeginError; pLevel = &pWInfo->a[ii]; wsFlags = pLevel->pWLoop->wsFlags; pSrc = &pTabList->a[pLevel->iFrom]; if( pSrc->fg.isMaterialized ){ if( pSrc->fg.isCorrelated ){ sqlite3VdbeAddOp2(v, OP_Gosub, pSrc->regReturn, pSrc->addrFillSub); }else{ int iOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v); sqlite3VdbeAddOp2(v, OP_Gosub, pSrc->regReturn, pSrc->addrFillSub); sqlite3VdbeJumpHere(v, iOnce); } } if( (wsFlags & (WHERE_AUTO_INDEX|WHERE_BLOOMFILTER))!=0 ){ if( (wsFlags & WHERE_AUTO_INDEX)!=0 ){ #ifndef SQLITE_OMIT_AUTOMATIC_INDEX constructAutomaticIndex(pParse, &pWInfo->sWC, &pTabList->a[pLevel->iFrom], notReady, pLevel); #endif }else{ sqlite3ConstructBloomFilter(pWInfo, ii, pLevel, notReady); } if( db->mallocFailed ) goto whereBeginError; } addrExplain = sqlite3WhereExplainOneScan( pParse, pTabList, pLevel, wctrlFlags ); pLevel->addrBody = sqlite3VdbeCurrentAddr(v); notReady = sqlite3WhereCodeOneLoopStart(pParse,v,pWInfo,ii,pLevel,notReady); pWInfo->iContinue = pLevel->addrCont; if( (wsFlags&WHERE_MULTI_OR)==0 && (wctrlFlags&WHERE_OR_SUBCLAUSE)==0 ){ sqlite3WhereAddScanStatus(v, pTabList, pLevel, addrExplain); } } /* Done. */ VdbeModuleComment((v, "Begin WHERE-core")); pWInfo->iEndWhere = sqlite3VdbeCurrentAddr(v); return pWInfo; /* Jump here if malloc fails */ whereBeginError: if( pWInfo ){ pParse->nQueryLoop = pWInfo->savedNQueryLoop; whereInfoFree(db, pWInfo); } return 0; } /* ** Part of sqlite3WhereEnd() will rewrite opcodes to reference the ** index rather than the main table. In SQLITE_DEBUG mode, we want ** to trace those changes if PRAGMA vdbe_addoptrace=on. This routine ** does that. */ #ifndef SQLITE_DEBUG # define OpcodeRewriteTrace(D,K,P) /* no-op */ #else # define OpcodeRewriteTrace(D,K,P) sqlite3WhereOpcodeRewriteTrace(D,K,P) static void sqlite3WhereOpcodeRewriteTrace( sqlite3 *db, int pc, VdbeOp *pOp ){ if( (db->flags & SQLITE_VdbeAddopTrace)==0 ) return; sqlite3VdbePrintOp(0, pc, pOp); } #endif #ifdef SQLITE_DEBUG /* ** Return true if cursor iCur is opened by instruction k of the ** bytecode. Used inside of assert() only. */ static int cursorIsOpen(Vdbe *v, int iCur, int k){ while( k>=0 ){ VdbeOp *pOp = sqlite3VdbeGetOp(v,k--); if( pOp->p1!=iCur ) continue; if( pOp->opcode==OP_Close ) return 0; if( pOp->opcode==OP_OpenRead ) return 1; if( pOp->opcode==OP_OpenWrite ) return 1; if( pOp->opcode==OP_OpenDup ) return 1; if( pOp->opcode==OP_OpenAutoindex ) return 1; if( pOp->opcode==OP_OpenEphemeral ) return 1; } return 0; } #endif /* SQLITE_DEBUG */ /* ** Generate the end of the WHERE loop. See comments on ** sqlite3WhereBegin() for additional information. */ void sqlite3WhereEnd(WhereInfo *pWInfo){ Parse *pParse = pWInfo->pParse; Vdbe *v = pParse->pVdbe; int i; WhereLevel *pLevel; WhereLoop *pLoop; SrcList *pTabList = pWInfo->pTabList; sqlite3 *db = pParse->db; int iEnd = sqlite3VdbeCurrentAddr(v); int nRJ = 0; /* Generate loop termination code. */ VdbeModuleComment((v, "End WHERE-core")); for(i=pWInfo->nLevel-1; i>=0; i--){ int addr; pLevel = &pWInfo->a[i]; if( pLevel->pRJ ){ /* Terminate the subroutine that forms the interior of the loop of ** the RIGHT JOIN table */ WhereRightJoin *pRJ = pLevel->pRJ; sqlite3VdbeResolveLabel(v, pLevel->addrCont); pLevel->addrCont = 0; pRJ->endSubrtn = sqlite3VdbeCurrentAddr(v); sqlite3VdbeAddOp3(v, OP_Return, pRJ->regReturn, pRJ->addrSubrtn, 1); VdbeCoverage(v); nRJ++; } pLoop = pLevel->pWLoop; if( pLevel->op!=OP_Noop ){ #ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT int addrSeek = 0; Index *pIdx; int n; if( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED && i==pWInfo->nLevel-1 /* Ticket [ef9318757b152e3] 2017-10-21 */ && (pLoop->wsFlags & WHERE_INDEXED)!=0 && (pIdx = pLoop->u.btree.pIndex)->hasStat1 && (n = pLoop->u.btree.nDistinctCol)>0 && pIdx->aiRowLogEst[n]>=36 ){ int r1 = pParse->nMem+1; int j, op; for(j=0; jiIdxCur, j, r1+j); } pParse->nMem += n+1; op = pLevel->op==OP_Prev ? OP_SeekLT : OP_SeekGT; addrSeek = sqlite3VdbeAddOp4Int(v, op, pLevel->iIdxCur, 0, r1, n); VdbeCoverageIf(v, op==OP_SeekLT); VdbeCoverageIf(v, op==OP_SeekGT); sqlite3VdbeAddOp2(v, OP_Goto, 1, pLevel->p2); } #endif /* SQLITE_DISABLE_SKIPAHEAD_DISTINCT */ /* The common case: Advance to the next row */ if( pLevel->addrCont ) sqlite3VdbeResolveLabel(v, pLevel->addrCont); sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3); sqlite3VdbeChangeP5(v, pLevel->p5); VdbeCoverage(v); VdbeCoverageIf(v, pLevel->op==OP_Next); VdbeCoverageIf(v, pLevel->op==OP_Prev); VdbeCoverageIf(v, pLevel->op==OP_VNext); if( pLevel->regBignull ){ sqlite3VdbeResolveLabel(v, pLevel->addrBignull); sqlite3VdbeAddOp2(v, OP_DecrJumpZero, pLevel->regBignull, pLevel->p2-1); VdbeCoverage(v); } #ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT if( addrSeek ) sqlite3VdbeJumpHere(v, addrSeek); #endif }else if( pLevel->addrCont ){ sqlite3VdbeResolveLabel(v, pLevel->addrCont); } if( (pLoop->wsFlags & WHERE_IN_ABLE)!=0 && pLevel->u.in.nIn>0 ){ struct InLoop *pIn; int j; sqlite3VdbeResolveLabel(v, pLevel->addrNxt); for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){ assert( sqlite3VdbeGetOp(v, pIn->addrInTop+1)->opcode==OP_IsNull || pParse->db->mallocFailed ); sqlite3VdbeJumpHere(v, pIn->addrInTop+1); if( pIn->eEndLoopOp!=OP_Noop ){ if( pIn->nPrefix ){ int bEarlyOut = (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 && (pLoop->wsFlags & WHERE_IN_EARLYOUT)!=0; if( pLevel->iLeftJoin ){ /* For LEFT JOIN queries, cursor pIn->iCur may not have been ** opened yet. This occurs for WHERE clauses such as ** "a = ? AND b IN (...)", where the index is on (a, b). If ** the RHS of the (a=?) is NULL, then the "b IN (...)" may ** never have been coded, but the body of the loop run to ** return the null-row. So, if the cursor is not open yet, ** jump over the OP_Next or OP_Prev instruction about to ** be coded. */ sqlite3VdbeAddOp2(v, OP_IfNotOpen, pIn->iCur, sqlite3VdbeCurrentAddr(v) + 2 + bEarlyOut); VdbeCoverage(v); } if( bEarlyOut ){ sqlite3VdbeAddOp4Int(v, OP_IfNoHope, pLevel->iIdxCur, sqlite3VdbeCurrentAddr(v)+2, pIn->iBase, pIn->nPrefix); VdbeCoverage(v); /* Retarget the OP_IsNull against the left operand of IN so ** it jumps past the OP_IfNoHope. This is because the ** OP_IsNull also bypasses the OP_Affinity opcode that is ** required by OP_IfNoHope. */ sqlite3VdbeJumpHere(v, pIn->addrInTop+1); } } sqlite3VdbeAddOp2(v, pIn->eEndLoopOp, pIn->iCur, pIn->addrInTop); VdbeCoverage(v); VdbeCoverageIf(v, pIn->eEndLoopOp==OP_Prev); VdbeCoverageIf(v, pIn->eEndLoopOp==OP_Next); } sqlite3VdbeJumpHere(v, pIn->addrInTop-1); } } sqlite3VdbeResolveLabel(v, pLevel->addrBrk); if( pLevel->pRJ ){ sqlite3VdbeAddOp3(v, OP_Return, pLevel->pRJ->regReturn, 0, 1); VdbeCoverage(v); } if( pLevel->addrSkip ){ sqlite3VdbeGoto(v, pLevel->addrSkip); VdbeComment((v, "next skip-scan on %s", pLoop->u.btree.pIndex->zName)); sqlite3VdbeJumpHere(v, pLevel->addrSkip); sqlite3VdbeJumpHere(v, pLevel->addrSkip-2); } #ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS if( pLevel->addrLikeRep ){ sqlite3VdbeAddOp2(v, OP_DecrJumpZero, (int)(pLevel->iLikeRepCntr>>1), pLevel->addrLikeRep); VdbeCoverage(v); } #endif if( pLevel->iLeftJoin ){ int ws = pLoop->wsFlags; addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin); VdbeCoverage(v); assert( (ws & WHERE_IDX_ONLY)==0 || (ws & WHERE_INDEXED)!=0 ); if( (ws & WHERE_IDX_ONLY)==0 ){ assert( pLevel->iTabCur==pTabList->a[pLevel->iFrom].iCursor ); sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iTabCur); } if( (ws & WHERE_INDEXED) || ((ws & WHERE_MULTI_OR) && pLevel->u.pCoveringIdx) ){ if( ws & WHERE_MULTI_OR ){ Index *pIx = pLevel->u.pCoveringIdx; int iDb = sqlite3SchemaToIndex(db, pIx->pSchema); sqlite3VdbeAddOp3(v, OP_ReopenIdx, pLevel->iIdxCur, pIx->tnum, iDb); sqlite3VdbeSetP4KeyInfo(pParse, pIx); } sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur); } if( pLevel->op==OP_Return ){ sqlite3VdbeAddOp2(v, OP_Gosub, pLevel->p1, pLevel->addrFirst); }else{ sqlite3VdbeGoto(v, pLevel->addrFirst); } sqlite3VdbeJumpHere(v, addr); } VdbeModuleComment((v, "End WHERE-loop%d: %s", i, pWInfo->pTabList->a[pLevel->iFrom].pTab->zName)); } assert( pWInfo->nLevel<=pTabList->nSrc ); for(i=0, pLevel=pWInfo->a; inLevel; i++, pLevel++){ int k, last; VdbeOp *pOp, *pLastOp; Index *pIdx = 0; SrcItem *pTabItem = &pTabList->a[pLevel->iFrom]; Table *pTab = pTabItem->pTab; assert( pTab!=0 ); pLoop = pLevel->pWLoop; /* Do RIGHT JOIN processing. Generate code that will output the ** unmatched rows of the right operand of the RIGHT JOIN with ** all of the columns of the left operand set to NULL. */ if( pLevel->pRJ ){ sqlite3WhereRightJoinLoop(pWInfo, i, pLevel); continue; } /* For a co-routine, change all OP_Column references to the table of ** the co-routine into OP_Copy of result contained in a register. ** OP_Rowid becomes OP_Null. */ if( pTabItem->fg.viaCoroutine ){ testcase( pParse->db->mallocFailed ); translateColumnToCopy(pParse, pLevel->addrBody, pLevel->iTabCur, pTabItem->regResult, 0); continue; } /* If this scan uses an index, make VDBE code substitutions to read data ** from the index instead of from the table where possible. In some cases ** this optimization prevents the table from ever being read, which can ** yield a significant performance boost. ** ** Calls to the code generator in between sqlite3WhereBegin and ** sqlite3WhereEnd will have created code that references the table ** directly. This loop scans all that code looking for opcodes ** that reference the table and converts them into opcodes that ** reference the index. */ if( pLoop->wsFlags & (WHERE_INDEXED|WHERE_IDX_ONLY) ){ pIdx = pLoop->u.btree.pIndex; }else if( pLoop->wsFlags & WHERE_MULTI_OR ){ pIdx = pLevel->u.pCoveringIdx; } if( pIdx && !db->mallocFailed ){ if( pWInfo->eOnePass==ONEPASS_OFF || !HasRowid(pIdx->pTable) ){ last = iEnd; }else{ last = pWInfo->iEndWhere; } if( pIdx->bHasExpr ){ IndexedExpr *p = pParse->pIdxExpr; while( p ){ if( p->iIdxCur==pLevel->iIdxCur ){ p->iDataCur = -1; p->iIdxCur = -1; } p = p->pIENext; } } k = pLevel->addrBody + 1; #ifdef SQLITE_DEBUG if( db->flags & SQLITE_VdbeAddopTrace ){ printf("TRANSLATE opcodes in range %d..%d\n", k, last-1); } /* Proof that the "+1" on the k value above is safe */ pOp = sqlite3VdbeGetOp(v, k - 1); assert( pOp->opcode!=OP_Column || pOp->p1!=pLevel->iTabCur ); assert( pOp->opcode!=OP_Rowid || pOp->p1!=pLevel->iTabCur ); assert( pOp->opcode!=OP_IfNullRow || pOp->p1!=pLevel->iTabCur ); #endif pOp = sqlite3VdbeGetOp(v, k); pLastOp = pOp + (last - k); assert( pOp<=pLastOp ); do{ if( pOp->p1!=pLevel->iTabCur ){ /* no-op */ }else if( pOp->opcode==OP_Column #ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC || pOp->opcode==OP_Offset #endif ){ int x = pOp->p2; assert( pIdx->pTable==pTab ); #ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC if( pOp->opcode==OP_Offset ){ /* Do not need to translate the column number */ }else #endif if( !HasRowid(pTab) ){ Index *pPk = sqlite3PrimaryKeyIndex(pTab); x = pPk->aiColumn[x]; assert( x>=0 ); }else{ testcase( x!=sqlite3StorageColumnToTable(pTab,x) ); x = sqlite3StorageColumnToTable(pTab,x); } x = sqlite3TableColumnToIndex(pIdx, x); if( x>=0 ){ pOp->p2 = x; pOp->p1 = pLevel->iIdxCur; OpcodeRewriteTrace(db, k, pOp); }else{ /* Unable to translate the table reference into an index ** reference. Verify that this is harmless - that the ** table being referenced really is open. */ #ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 || cursorIsOpen(v,pOp->p1,k) || pOp->opcode==OP_Offset ); #else assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 || cursorIsOpen(v,pOp->p1,k) ); #endif } }else if( pOp->opcode==OP_Rowid ){ pOp->p1 = pLevel->iIdxCur; pOp->opcode = OP_IdxRowid; OpcodeRewriteTrace(db, k, pOp); }else if( pOp->opcode==OP_IfNullRow ){ pOp->p1 = pLevel->iIdxCur; OpcodeRewriteTrace(db, k, pOp); } #ifdef SQLITE_DEBUG k++; #endif }while( (++pOp)flags & SQLITE_VdbeAddopTrace ) printf("TRANSLATE complete\n"); #endif } } /* The "break" point is here, just past the end of the outer loop. ** Set it. */ sqlite3VdbeResolveLabel(v, pWInfo->iBreak); /* Final cleanup */ pParse->nQueryLoop = pWInfo->savedNQueryLoop; whereInfoFree(db, pWInfo); pParse->withinRJSubrtn -= nRJ; return; }