diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/where.c | 44 |
1 files changed, 36 insertions, 8 deletions
diff --git a/src/where.c b/src/where.c index 9b64fd72f..bd8a7541f 100644 --- a/src/where.c +++ b/src/where.c @@ -262,6 +262,8 @@ struct WhereCost { #define WHERE_REVERSE 0x01000000 /* Scan in reverse order */ #define WHERE_UNIQUE 0x02000000 /* Selects no more than one row */ #define WHERE_ALL_UNIQUE 0x04000000 /* This and all prior have one row */ +#define WHERE_OB_UNIQUE 0x00004000 /* Values in ORDER BY columns are + ** different for every output row */ #define WHERE_VIRTUALTABLE 0x08000000 /* Use virtual-table processing */ #define WHERE_MULTI_OR 0x10000000 /* OR using multiple indices */ #define WHERE_TEMP_INDEX 0x20000000 /* Uses an ephemeral index */ @@ -2903,7 +2905,8 @@ static int isSortingIndex( WhereBestIdx *p, /* Best index search context */ Index *pIdx, /* The index we are testing */ int base, /* Cursor number for the table to be sorted */ - int *pbRev /* Set to 1 for reverse-order scan of pIdx */ + int *pbRev, /* Set to 1 for reverse-order scan of pIdx */ + int *pbObUnique /* ORDER BY column values will different in every row */ ){ int i; /* Number of pIdx terms used */ int j; /* Number of ORDER BY terms satisfied */ @@ -2917,12 +2920,16 @@ static int isSortingIndex( int nPriorSat; /* ORDER BY terms satisfied by outer loops */ int seenRowid = 0; /* True if an ORDER BY rowid term is seen */ int uniqueNotNull; /* pIdx is UNIQUE with all terms are NOT NULL */ + int outerObUnique; /* Outer loops generate different values in + ** every row for the ORDER BY columns */ if( p->i==0 ){ nPriorSat = 0; + outerObUnique = 1; }else{ + u32 wsFlags = p->aLevel[p->i-1].plan.wsFlags; nPriorSat = p->aLevel[p->i-1].plan.nOBSat; - if( (p->aLevel[p->i-1].plan.wsFlags & WHERE_ORDERED)==0 ){ + if( (wsFlags & WHERE_ORDERED)==0 ){ /* This loop cannot be ordered unless the next outer loop is ** also ordered */ return nPriorSat; @@ -2932,6 +2939,9 @@ static int isSortingIndex( ** optimization is disabled */ return nPriorSat; } + testcase( wsFlags & WHERE_OB_UNIQUE ); + testcase( wsFlags & WHERE_ALL_UNIQUE ); + outerObUnique = (wsFlags & (WHERE_OB_UNIQUE|WHERE_ALL_UNIQUE))!=0; } pOrderBy = p->pOrderBy; assert( pOrderBy!=0 ); @@ -3073,11 +3083,26 @@ static int isSortingIndex( uniqueNotNull = 0; } } + if( seenRowid ){ + uniqueNotNull = 1; + }else if( uniqueNotNull==0 || i<pIdx->nColumn ){ + uniqueNotNull = 0; + } /* If we have not found at least one ORDER BY term that matches the ** index, then show no progress. */ if( pOBItem==&pOrderBy->a[nPriorSat] ) return nPriorSat; + /* Either the outer queries must generate rows where there are no two + ** rows with the same values in all ORDER BY columns, or else this + ** loop must generate just a single row of output. Example: Suppose + ** the outer loops generate A=1 and A=1, and this loop generates B=3 + ** and B=4. Then without the following test, ORDER BY A,B would + ** generate the wrong order output: 1,3 1,4 1,3 1,4 + */ + if( outerObUnique==0 && uniqueNotNull==0 ) return nPriorSat; + *pbObUnique = uniqueNotNull; + /* Return the necessary scan order back to the caller */ *pbRev = sortOrder & 1; @@ -3085,7 +3110,7 @@ static int isSortingIndex( ** possible for a single row from this table to match, then skip over ** any additional ORDER BY terms dealing with this table. */ - if( seenRowid || (uniqueNotNull && i>=pIdx->nColumn) ){ + if( uniqueNotNull ){ /* Advance j over additional ORDER BY terms associated with base */ WhereMaskSet *pMS = p->pWC->pMaskSet; Bitmask m = ~getMask(pMS, base); @@ -3369,12 +3394,14 @@ static void bestBtreeIndex(WhereBestIdx *p){ ** variable. */ if( bSort && (pSrc->jointype & JT_LEFT)==0 ){ int bRev = 2; - WHERETRACE((" --> before isSortingIndex: nPriorSat=%d\n",nPriorSat)); - pc.plan.nOBSat = isSortingIndex(p, pProbe, iCur, &bRev); - WHERETRACE((" --> after isSortingIndex: bRev=%d nOBSat=%d\n", - bRev, pc.plan.nOBSat)); + int bObUnique = 0; + WHERETRACE((" --> before isSortIndex: nPriorSat=%d\n",nPriorSat)); + pc.plan.nOBSat = isSortingIndex(p, pProbe, iCur, &bRev, &bObUnique); + WHERETRACE((" --> after isSortIndex: bRev=%d bObU=%d nOBSat=%d\n", + bRev, bObUnique, pc.plan.nOBSat)); if( nPriorSat<pc.plan.nOBSat || (pc.plan.wsFlags & WHERE_ALL_UNIQUE)!=0 ){ pc.plan.wsFlags |= WHERE_ORDERED; + if( bObUnique ) pc.plan.wsFlags |= WHERE_OB_UNIQUE; } if( nOrderBy==pc.plan.nOBSat ){ bSort = 0; @@ -3468,7 +3495,8 @@ static void bestBtreeIndex(WhereBestIdx *p){ ** So this computation assumes table records are about twice as big ** as index records */ - if( (pc.plan.wsFlags&~(WHERE_REVERSE|WHERE_ORDERED))==WHERE_IDX_ONLY + if( (pc.plan.wsFlags&~(WHERE_REVERSE|WHERE_ORDERED|WHERE_OB_UNIQUE)) + ==WHERE_IDX_ONLY && (pWC->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 && sqlite3GlobalConfig.bUseCis && OptimizationEnabled(pParse->db, SQLITE_CoverIdxScan) |