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Further refinement of the idea of multiplying run-time cost estimates by

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the estimated row size.

FossilOrigin-Name: 18bd6ba96d19de6047baebfa15b1f739577c9ec4
This commit is contained in:
drh
2013-10-08 18:40:37 +00:00
parent 3495d20dbe
commit 186ad8cc32
7 changed files with 51 additions and 60 deletions
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21
src/select.c
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@@ -1424,8 +1424,7 @@ static int selectColumnsFromExprList(
*/
static void selectAddColumnTypeAndCollation(
Parse *pParse, /* Parsing contexts */
int nCol, /* Number of columns */
Column *aCol, /* List of columns */
Table *pTab, /* Add column type information to this table */
Select *pSelect /* SELECT used to determine types and collations */
){
sqlite3 *db = pParse->db;
@@ -1435,17 +1434,20 @@ static void selectAddColumnTypeAndCollation(
int i;
Expr *p;
struct ExprList_item *a;
u64 szAll = 0;
assert( pSelect!=0 );
assert( (pSelect->selFlags & SF_Resolved)!=0 );
assert( nCol==pSelect->pEList->nExpr || db->mallocFailed );
assert( pTab->nCol==pSelect->pEList->nExpr || db->mallocFailed );
if( db->mallocFailed ) return;
memset(&sNC, 0, sizeof(sNC));
sNC.pSrcList = pSelect->pSrc;
a = pSelect->pEList->a;
for(i=0, pCol=aCol; i<nCol; i++, pCol++){
for(i=0, pCol=pTab->aCol; i<pTab->nCol; i++, pCol++){
p = a[i].pExpr;
pCol->zType = sqlite3DbStrDup(db, columnType(&sNC, p, 0, 0, 0));
sqlite3AffinityType(pCol->zType, &pCol->szEst);
szAll += pCol->szEst;
pCol->affinity = sqlite3ExprAffinity(p);
if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_NONE;
pColl = sqlite3ExprCollSeq(pParse, p);
@@ -1453,6 +1455,7 @@ static void selectAddColumnTypeAndCollation(
pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
}
}
pTab->szTabRow = sqlite3LogEst(szAll*4);
}
/*
@@ -1480,9 +1483,9 @@ Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){
assert( db->lookaside.bEnabled==0 );
pTab->nRef = 1;
pTab->zName = 0;
pTab->nRowEst = 1000000;
pTab->nRowEst = 1048576;
selectColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol);
selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSelect);
selectAddColumnTypeAndCollation(pParse, pTab, pSelect);
pTab->iPKey = -1;
if( db->mallocFailed ){
sqlite3DeleteTable(db, pTab);
@@ -3394,11 +3397,11 @@ static int selectExpander(Walker *pWalker, Select *p){
pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
if( pTab==0 ) return WRC_Abort;
pTab->nRef = 1;
pTab->zName = sqlite3MPrintf(db, "sqlite_subquery_%p_", (void*)pTab);
pTab->zName = sqlite3MPrintf(db, "sqlite_sq_%p", (void*)pTab);
while( pSel->pPrior ){ pSel = pSel->pPrior; }
selectColumnsFromExprList(pParse, pSel->pEList, &pTab->nCol, &pTab->aCol);
pTab->iPKey = -1;
pTab->nRowEst = 1000000;
pTab->nRowEst = 1048576;
pTab->tabFlags |= TF_Ephemeral;
#endif
}else{
@@ -3682,7 +3685,7 @@ static int selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){
Select *pSel = pFrom->pSelect;
assert( pSel );
while( pSel->pPrior ) pSel = pSel->pPrior;
selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSel);
selectAddColumnTypeAndCollation(pParse, pTab, pSel);
}
}
}