Improved detection of unnecessary ORDER BY clauses.
FossilOrigin-Name: 58805eb36b9975706e2c4e382689519454e9a504
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drh
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53b52f7f2e
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12
manifest
12
manifest
@ -1,5 +1,5 @@
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C Fix\sthe\sconstructAutomaticIndex()\sroutine\sso\sthat\sit\sworks\swith\sNGQP.
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D 2013-05-31T11:57:39.405
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C Improved\sdetection\sof\sunnecessary\sORDER\sBY\sclauses.
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D 2013-05-31T12:43:55.143
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F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
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F Makefile.in 5e41da95d92656a5004b03d3576e8b226858a28e
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F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
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@ -289,7 +289,7 @@ F src/vtab.c b05e5f1f4902461ba9f5fc49bb7eb7c3a0741a83
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F src/wal.c 436bfceb141b9423c45119e68e444358ee0ed35d
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F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
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F src/walker.c 4fa43583d0a84b48f93b1e88f11adf2065be4e73
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F src/where.c 530dd22d4f803747e964edcb052d699c4c92e1a1
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F src/where.c 0e1c41804f89dbfd48fbe8dfa68adc6b6d682a75
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F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
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F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
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F test/aggnested.test 45c0201e28045ad38a530b5a144b73cd4aa2cfd6
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@ -1093,7 +1093,7 @@ F tool/vdbe-compress.tcl f12c884766bd14277f4fcedcae07078011717381
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F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
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F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
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F tool/win/sqlite.vsix 97894c2790eda7b5bce3cc79cb2a8ec2fde9b3ac
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P 24a2e9ddcecd3926817d77abbb75d068ee7140ad
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R 92deaa75392a3f586cae6bde8f65a470
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P 5e1e61399513b4a95fd93df2377a2603f1670063
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R 17288f799b200fcc6199a08359305634
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U drh
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Z 293d3cdab228aa747c73a2994c326e63
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Z 9542ccfa5fa5ec11248b1f41f8b389ee
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@ -1 +1 @@
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5e1e61399513b4a95fd93df2377a2603f1670063
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58805eb36b9975706e2c4e382689519454e9a504
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35
src/where.c
35
src/where.c
@ -3832,7 +3832,7 @@ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
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** is better and has fewer dependencies. Or the template will be ignored
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** and no insert will occur if an existing WhereLoop is faster and has
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** fewer dependencies than the template. Otherwise a new WhereLoop is
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** added based no the template.
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** added based on the template.
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**
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** If pBuilder->pBest is not NULL then we only care about the very
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** best template and that template should be stored in pBuilder->pBest.
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@ -3848,6 +3848,8 @@ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
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** (2) They have the same iSortIdx.
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** (3) The template has same or fewer dependencies than the current loop
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** (4) The template has the same or lower cost than the current loop
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** (5) The template uses more terms of the same index but has no additional
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** dependencies
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*/
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static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){
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WhereLoop **ppPrev, *p, *pNext = 0, *pToFree = 0;
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@ -4100,7 +4102,7 @@ static int whereLoopAddBtree(
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struct SrcList_item *pSrc; /* The FROM clause btree term to add */
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WhereLoop *pNew; /* Template WhereLoop object */
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int rc = SQLITE_OK; /* Return code */
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int iSortIdx = 0; /* Index number */
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int iSortIdx = 1; /* Index number */
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int b; /* A boolean value */
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double rSize; /* number of rows in the table */
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double rLogSize; /* Logarithm of the number of rows in the table */
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@ -4179,6 +4181,7 @@ static int whereLoopAddBtree(
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pNew->wsFlags = WHERE_IPK;
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/* Full table scan */
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pNew->iSortIdx = b ? iSortIdx : 0;
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pNew->nOut = rSize;
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pNew->rRun = (rSize + rLogSize)*(3+b); /* 4x penalty for a full-scan */
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rc = whereLoopInsert(pBuilder, pNew);
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@ -4513,8 +4516,9 @@ static int wherePathSatisfiesOrderBy(
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u8 revSet; /* True if rev is known */
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u8 rev; /* Composite sort order */
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u8 revIdx; /* Index sort order */
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u8 isUnique;
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u8 requireUnique = 0;
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u8 isOneRow; /* Current WhereLoop is a one-row loop */
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u8 requireOneRow = 0; /* All subsequent loops must be one-row */
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u8 isUniqueIdx; /* Current WhereLoop uses a unique index */
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u16 nColumn;
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u16 nOrderBy;
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int i, j;
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@ -4547,6 +4551,10 @@ static int wherePathSatisfiesOrderBy(
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** of the index.
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**
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** (4) Index columns past nEq must match ORDER BY terms one-for-one.
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**
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** (5) If all columns of a UNIQUE index have been matched against ORDER BY
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** terms, then any subsequent entries in the ORDER BY clause against the
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** same table can be skipped.
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*/
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assert( pOrderBy!=0 );
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@ -4569,10 +4577,10 @@ static int wherePathSatisfiesOrderBy(
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for(i=0; i<=nLoop && nUsed<nOrderBy; i++){
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pLoop = i<nLoop ? pPath->aLoop[i] : pLast;
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assert( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 );
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isUnique = 1;
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isOneRow = isUniqueIdx = 1;
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if( pLoop->wsFlags & WHERE_IPK ){
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if( (pLoop->wsFlags & WHERE_COLUMN_IN)!=0 ) isUnique = 0;
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if( pLoop->u.btree.nEq!=1 ) isUnique = 0;
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if( (pLoop->wsFlags & WHERE_COLUMN_IN)!=0 ) isOneRow = 0;
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if( pLoop->u.btree.nEq!=1 ) isOneRow = 0;
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pIndex = 0;
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nColumn = 0;
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}else if( (pIndex = pLoop->u.btree.pIndex)==0 || pIndex->bUnordered ){
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@ -4580,16 +4588,16 @@ static int wherePathSatisfiesOrderBy(
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}else{
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nColumn = pIndex->nColumn;
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if( pIndex->onError==OE_None ){
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isUnique = 0;
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isOneRow = isUniqueIdx = 0;
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}else if( (pLoop->wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_RANGE
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|WHERE_COLUMN_NULL))!=0 ){
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isUnique = 0;
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isOneRow = 0;
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}else if( pLoop->u.btree.nEq < pIndex->nColumn ){
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isUnique = 0;
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isOneRow = 0;
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}
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}
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if( !isUnique && requireUnique ) return 0;
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requireUnique = !isUnique;
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if( !isOneRow && requireOneRow ) return 0;
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requireOneRow = !isOneRow;
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iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor;
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j = 0;
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revSet = rev = 0;
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@ -4598,7 +4606,7 @@ static int wherePathSatisfiesOrderBy(
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pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[nUsed].pExpr);
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assert( pOBExpr->op==TK_COLUMN );
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if( pOBExpr->iTable!=iCur ) break;
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if( isUnique ) continue;
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if( isOneRow ){ j--; continue; }
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if( j<nColumn ){
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/* Normal index columns */
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iColumn = pIndex->aiColumn[j];
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@ -4629,6 +4637,7 @@ static int wherePathSatisfiesOrderBy(
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revSet = 1;
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}
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}
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if( j>=nColumn-1 && isUniqueIdx ){ j--; isOneRow = 1; }
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}
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if( rev ) revMask |= ((Bitmask)1)<<i;
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}
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