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Refactor the SrcItem object so that information about subqueries is stored

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in a separately allocated Subquery object.  This reduces the memory requirements
for SrcItem and makes the code run faster.  It also provides an expansion path
for subquery processing that does not burden simple queries.  The current
checking mostly works, but there are still issues that need to be tracked
down and fixed.

FossilOrigin-Name: 8ff5dda8448d7e1a533d7f27db2573ce68fa9956b9d9847ced45e83c1f06bab0
This commit is contained in:
drh
2024-08-19 22:48:30 +00:00
parent b204b6aa7b
commit 1521ca4c20
18 changed files with 419 additions and 204 deletions
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18
src/window.c
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@@ -1077,9 +1077,10 @@ int sqlite3WindowRewrite(Parse *pParse, Select *p){
assert( pSub!=0 || p->pSrc==0 ); /* Due to db->mallocFailed test inside
** of sqlite3DbMallocRawNN() called from
** sqlite3SrcListAppend() */
if( p->pSrc ){
if( p->pSrc==0 ){
sqlite3SelectDelete(db, pSub);
}else if( sqlite3SrcItemAttachSubquery(pParse, &p->pSrc->a[0], pSub, 0) ){
Table *pTab2;
p->pSrc->a[0].sq.pSelect = pSub;
p->pSrc->a[0].fg.isCorrelated = 1;
sqlite3SrcListAssignCursors(pParse, p->pSrc);
pSub->selFlags |= SF_Expanded|SF_OrderByReqd;
@@ -1101,8 +1102,6 @@ int sqlite3WindowRewrite(Parse *pParse, Select *p){
w.xSelectCallback2 = sqlite3WalkerDepthDecrease;
sqlite3WalkSelect(&w, pSub);
}
}else{
sqlite3SelectDelete(db, pSub);
}
if( db->mallocFailed ) rc = SQLITE_NOMEM;
@@ -1389,10 +1388,15 @@ int sqlite3WindowCompare(
** and initialize registers and cursors used by sqlite3WindowCodeStep().
*/
void sqlite3WindowCodeInit(Parse *pParse, Select *pSelect){
int nEphExpr = pSelect->pSrc->a[0].sq.pSelect->pEList->nExpr;
Window *pMWin = pSelect->pWin;
Window *pWin;
Vdbe *v = sqlite3GetVdbe(pParse);
int nEphExpr;
Window *pMWin;
Vdbe *v;
assert( pSelect->pSrc->a[0].fg.isSubquery );
nEphExpr = pSelect->pSrc->a[0].u4.pSubq->pSelect->pEList->nExpr;
pMWin = pSelect->pWin;
v = sqlite3GetVdbe(pParse);
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pMWin->iEphCsr, nEphExpr);
sqlite3VdbeAddOp2(v, OP_OpenDup, pMWin->iEphCsr+1, pMWin->iEphCsr);