diff options
Diffstat (limited to 'src/where.c')
| -rw-r--r-- | src/where.c | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/src/where.c b/src/where.c index 7d2f1f73b..4ddb37012 100644 --- a/src/where.c +++ b/src/where.c @@ -45,7 +45,13 @@ typedef struct WherePath WherePath; typedef struct WhereTerm WhereTerm; typedef struct WhereLoopBuilder WhereLoopBuilder; typedef struct WhereScan WhereScan; -typedef unsigned short int WhereCost; /* 10 times log2() of run-time */ + +/* +** Cost X is tracked as 10*log2(X) stored in a 16-bit integer. The +** maximum cost is 64*(2**63) which becomes 6900. So all costs can be +** be stored in a 16-bit unsigned integer without risk of overflow. +*/ +typedef unsigned short int WhereCost; /* ** For each nested loop in a WHERE clause implementation, the WhereInfo @@ -401,11 +407,25 @@ struct WhereInfo { #define WHERE_TEMP_INDEX 0x00004000 /* Uses an ephemeral index */ #define WHERE_COVER_SCAN 0x00008000 /* Full scan of a covering index */ + +/* Convert a WhereCost value (10 times log2(X)) into its integer value X. +*/ +static u64 whereCostToInt(WhereCost x){ + u64 n; + if( x<=10 ) return 1; + n = x%10; + x /= 10; + if( n>=5 ) n -= 2; + else if( n>=1 ) n -= 1; + if( x>=3 ) return (n+8)<<(x-3); + return (n+8)>>(3-x); +} + /* ** Return the estimated number of output rows from a WHERE clause */ -double sqlite3WhereOutputRowCount(WhereInfo *pWInfo){ - return (double)pWInfo->nRowOut; +u64 sqlite3WhereOutputRowCount(WhereInfo *pWInfo){ + return whereCostToInt(pWInfo->nRowOut); } /* @@ -4716,6 +4736,7 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){ sqlite3 *db = pWInfo->pParse->db; int nTabList = pWInfo->nLevel; int rc = SQLITE_OK; + u8 priorJoinType = 0; WhereLoop *pNew; /* Loop over the tables in the join, from left to right */ @@ -4724,9 +4745,10 @@ static int whereLoopAddAll(WhereLoopBuilder *pBuilder){ for(iTab=0, pItem=pTabList->a; iTab<nTabList; iTab++, pItem++){ pNew->iTab = iTab; pNew->maskSelf = getMask(&pWInfo->sMaskSet, pItem->iCursor); - if( (pItem->jointype & (JT_LEFT|JT_CROSS))!=0 ){ + if( ((pItem->jointype|priorJoinType) & (JT_LEFT|JT_CROSS))!=0 ){ mExtra = mPrior; } + priorJoinType = pItem->jointype; if( IsVirtual(pItem->pTab) ){ rc = whereLoopAddVirtual(pBuilder, mExtra); }else{ |