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Add an optimization that attempts to run a subquery as a coroutine rather

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than manifesting it into a temporary table.

FossilOrigin-Name: 7af3acbbd49a2114fcdada9ec907c68ba9b053bd
This commit is contained in:
drh
2012-10-30 00:29:07 +00:00
parent 6e227bf3e0
commit 21172c4cc0
13 changed files with 104 additions and 40 deletions
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18
src/vdbe.c
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@@ -2207,7 +2207,10 @@ case OP_Column: {
** the number of columns is stored in the VdbeCursor.nField element.
*/
pC = p->apCsr[p1];
assert( pC!=0 );
if( pC==0 ){
sqlite3VdbeMemSetNull(pDest);
goto op_column_out;
}
#ifndef SQLITE_OMIT_VIRTUALTABLE
assert( pC->pVtabCursor==0 );
#endif
@@ -2237,6 +2240,11 @@ case OP_Column: {
}
}else if( ALWAYS(pC->pseudoTableReg>0) ){
pReg = &aMem[pC->pseudoTableReg];
if( pC->multiPseudo ){
sqlite3VdbeMemShallowCopy(pDest, pReg+p2, MEM_Ephem);
Deephemeralize(pDest);
goto op_column_out;
}
assert( pReg->flags & MEM_Blob );
assert( memIsValid(pReg) );
payloadSize = pReg->n;
@@ -3322,8 +3330,9 @@ case OP_SorterOpen: {
**
** Open a new cursor that points to a fake table that contains a single
** row of data. The content of that one row in the content of memory
** register P2. In other words, cursor P1 becomes an alias for the
** MEM_Blob content contained in register P2.
** register P2 when P5==0. In other words, cursor P1 becomes an alias for the
** MEM_Blob content contained in register P2. When P5==1, then the
** row is represented by P3 consecutive registers beginning with P2.
**
** A pseudo-table created by this opcode is used to hold a single
** row output from the sorter so that the row can be decomposed into
@@ -3343,6 +3352,7 @@ case OP_OpenPseudo: {
pCx->pseudoTableReg = pOp->p2;
pCx->isTable = 1;
pCx->isIndex = 0;
pCx->multiPseudo = pOp->p5;
break;
}
@@ -4307,7 +4317,7 @@ case OP_Rowid: { /* out2-prerelease */
assert( pOp->p1>=0 && pOp->p1<p->nCursor );
pC = p->apCsr[pOp->p1];
assert( pC!=0 );
assert( pC->pseudoTableReg==0 );
assert( pC->pseudoTableReg==0 || pC->nullRow );
if( pC->nullRow ){
pOut->flags = MEM_Null;
break;