diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/select.c | 44 | ||||
| -rw-r--r-- | src/sqliteInt.h | 1 | ||||
| -rw-r--r-- | src/test1.c | 1 |
3 files changed, 32 insertions, 14 deletions
diff --git a/src/select.c b/src/select.c index 7f15c2acb..b89f09a95 100644 --- a/src/select.c +++ b/src/select.c @@ -3296,6 +3296,8 @@ static int multiSelectOrderBy( ){ int i, j; /* Loop counters */ Select *pPrior; /* Another SELECT immediately to our left */ + Select *pSplit; /* Left-most SELECT in the right-hand group */ + int nSelect; /* Number of SELECT statements in the compound */ Vdbe *v; /* Generate code to this VDBE */ SelectDest destA; /* Destination for coroutine A */ SelectDest destB; /* Destination for coroutine B */ @@ -3341,8 +3343,7 @@ static int multiSelectOrderBy( /* Patch up the ORDER BY clause */ op = p->op; - pPrior = p->pPrior; - assert( pPrior->pOrderBy==0 ); + assert( p->pPrior->pOrderBy==0 ); pOrderBy = p->pOrderBy; assert( pOrderBy ); nOrderBy = pOrderBy->nExpr; @@ -3392,11 +3393,6 @@ static int multiSelectOrderBy( pKeyMerge = 0; } - /* Reattach the ORDER BY clause to the query. - */ - p->pOrderBy = pOrderBy; - pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0); - /* Allocate a range of temporary registers and the KeyInfo needed ** for the logic that removes duplicate result rows when the ** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL). @@ -3421,9 +3417,30 @@ static int multiSelectOrderBy( /* Separate the left and the right query from one another */ - p->pPrior = 0; + nSelect = 1; + if( (op==TK_ALL || op==TK_UNION) + && OptimizationEnabled(db, SQLITE_BalancedMerge) + ){ + for(pSplit=p; pSplit->pPrior!=0 && pSplit->op==op; pSplit=pSplit->pPrior){ + nSelect++; + assert( pSplit->pPrior->pNext==pSplit ); + } + } + if( nSelect<=3 ){ + pSplit = p; + }else{ + pSplit = p; + for(i=2; i<nSelect; i+=2){ pSplit = pSplit->pPrior; } + } + pPrior = pSplit->pPrior; + pSplit->pPrior = 0; pPrior->pNext = 0; - sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER"); + assert( p->pOrderBy == pOrderBy ); + assert( pOrderBy!=0 || db->mallocFailed ); + pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0); + if( p->pPrior==0 ){ + sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER"); + } if( pPrior->pPrior==0 ){ sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER"); } @@ -3577,12 +3594,11 @@ static int multiSelectOrderBy( /* Reassembly the compound query so that it will be freed correctly ** by the calling function */ - if( p->pPrior ){ - sqlite3SelectDelete(db, p->pPrior); + if( pSplit->pPrior ){ + sqlite3SelectDelete(db, pSplit->pPrior); } - p->pPrior = pPrior; - pPrior->pNext = p; - + pSplit->pPrior = pPrior; + pPrior->pNext = pSplit; sqlite3ExprListDelete(db, pPrior->pOrderBy); pPrior->pOrderBy = 0; diff --git a/src/sqliteInt.h b/src/sqliteInt.h index 092bbccdc..ac2414a24 100644 --- a/src/sqliteInt.h +++ b/src/sqliteInt.h @@ -1764,6 +1764,7 @@ struct sqlite3 { /* TH3 expects this value ^^^^^^^^^^ to be 0x40000. Coordinate any change */ #define SQLITE_BloomFilter 0x00080000 /* Use a Bloom filter on searches */ #define SQLITE_BloomPulldown 0x00100000 /* Run Bloom filters early */ +#define SQLITE_BalancedMerge 0x00200000 /* Balance multi-way merges */ #define SQLITE_AllOpts 0xffffffff /* All optimizations */ /* diff --git a/src/test1.c b/src/test1.c index 520f4145e..b7fdd2a4b 100644 --- a/src/test1.c +++ b/src/test1.c @@ -7512,6 +7512,7 @@ static int SQLITE_TCLAPI optimization_control( { "stat4", SQLITE_Stat4 }, { "skip-scan", SQLITE_SkipScan }, { "push-down", SQLITE_PushDown }, + { "balanced-merge", SQLITE_BalancedMerge }, }; if( objc!=4 ){ |