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Overview
| Comment: | Avoid a performance problem when very large "VALUES(..), (..), (..)" terms are used in queries. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | recursive-selectdup |
| Files: | files | file ages | folders |
| SHA1: |
f5306ad6816cc377036685cdae227e76 |
| User & Date: | dan 2017-02-03 19:16:39 |
Context
|
2017-02-03
| ||
| 20:54 | Improved performance and stack usage when processing VALUES clauses with a very large number of rows. check-in: 5706d470 user: drh tags: trunk | |
| 19:16 | Avoid a performance problem when very large "VALUES(..), (..), (..)" terms are used in queries. Closed-Leaf check-in: f5306ad6 user: dan tags: recursive-selectdup | |
| 14:44 | Modify the sqlite3SelectDup() routine to avoid recursing on Select.pPrior. check-in: a7674ead user: dan tags: recursive-selectdup | |
Changes
Changes to src/select.c.
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return SQLITE_ERROR;
}
assert( pTab->nTabRef==1 || ((pSel->selFlags&SF_Recursive) && pTab->nTabRef==2 ));
pCte->zCteErr = "circular reference: %s";
pSavedWith = pParse->pWith;
pParse->pWith = pWith;
sqlite3WalkSelect(pWalker, bMayRecursive ? pSel->pPrior : pSel);
pParse->pWith = pWith;
for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior);
pEList = pLeft->pEList;
if( pCte->pCols ){
if( pEList && pEList->nExpr!=pCte->pCols->nExpr ){
sqlite3ErrorMsg(pParse, "table %s has %d values for %d columns",
................................................................................
**
** This function is used as the xSelectCallback2() callback by
** sqlite3SelectExpand() when walking a SELECT tree to resolve table
** names and other FROM clause elements.
*/
static void selectPopWith(Walker *pWalker, Select *p){
Parse *pParse = pWalker->pParse;
With *pWith = findRightmost(p)->pWith;
if( pWith!=0 ){
assert( pParse->pWith==pWith );
pParse->pWith = pWith->pOuter;
}
}
#else
#define selectPopWith 0
#endif
/*
................................................................................
return WRC_Abort;
}
if( NEVER(p->pSrc==0) || (selFlags & SF_Expanded)!=0 ){
return WRC_Prune;
}
pTabList = p->pSrc;
pEList = p->pEList;
if( pWalker->xSelectCallback2==selectPopWith ){
sqlite3WithPush(pParse, findRightmost(p)->pWith, 0);
}
/* Make sure cursor numbers have been assigned to all entries in
** the FROM clause of the SELECT statement.
*/
sqlite3SrcListAssignCursors(pParse, pTabList);
................................................................................
w.xExprCallback = sqlite3ExprWalkNoop;
w.pParse = pParse;
if( pParse->hasCompound ){
w.xSelectCallback = convertCompoundSelectToSubquery;
sqlite3WalkSelect(&w, pSelect);
}
w.xSelectCallback = selectExpander;
if( (pSelect->selFlags & SF_MultiValue)==0 ){
w.xSelectCallback2 = selectPopWith;
}
sqlite3WalkSelect(&w, pSelect);
}
#ifndef SQLITE_OMIT_SUBQUERY
/*
** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()
|
> > > > > > > | > > | | | | > | | < | < |
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return SQLITE_ERROR;
}
assert( pTab->nTabRef==1 || ((pSel->selFlags&SF_Recursive) && pTab->nTabRef==2 ));
pCte->zCteErr = "circular reference: %s";
pSavedWith = pParse->pWith;
pParse->pWith = pWith;
if( bMayRecursive ){
Select *pPrior = pSel->pPrior;
assert( pPrior->pWith==0 );
pPrior->pWith = pSel->pWith;
sqlite3WalkSelect(pWalker, pPrior);
pPrior->pWith = 0;
}else{
sqlite3WalkSelect(pWalker, pSel);
}
pParse->pWith = pWith;
for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior);
pEList = pLeft->pEList;
if( pCte->pCols ){
if( pEList && pEList->nExpr!=pCte->pCols->nExpr ){
sqlite3ErrorMsg(pParse, "table %s has %d values for %d columns",
................................................................................
**
** This function is used as the xSelectCallback2() callback by
** sqlite3SelectExpand() when walking a SELECT tree to resolve table
** names and other FROM clause elements.
*/
static void selectPopWith(Walker *pWalker, Select *p){
Parse *pParse = pWalker->pParse;
if( pParse->pWith && p->pPrior==0 ){
With *pWith = findRightmost(p)->pWith;
if( pWith!=0 ){
assert( pParse->pWith==pWith );
pParse->pWith = pWith->pOuter;
}
}
}
#else
#define selectPopWith 0
#endif
/*
................................................................................
return WRC_Abort;
}
if( NEVER(p->pSrc==0) || (selFlags & SF_Expanded)!=0 ){
return WRC_Prune;
}
pTabList = p->pSrc;
pEList = p->pEList;
if( p->pWith ){
sqlite3WithPush(pParse, p->pWith, 0);
}
/* Make sure cursor numbers have been assigned to all entries in
** the FROM clause of the SELECT statement.
*/
sqlite3SrcListAssignCursors(pParse, pTabList);
................................................................................
w.xExprCallback = sqlite3ExprWalkNoop;
w.pParse = pParse;
if( pParse->hasCompound ){
w.xSelectCallback = convertCompoundSelectToSubquery;
sqlite3WalkSelect(&w, pSelect);
}
w.xSelectCallback = selectExpander;
w.xSelectCallback2 = selectPopWith;
sqlite3WalkSelect(&w, pSelect);
}
#ifndef SQLITE_OMIT_SUBQUERY
/*
** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()
|