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Add code to handle recursive CTEs.

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FossilOrigin-Name: a5c2a54a07d35166911abc792008c05dea897742
This commit is contained in:
dan
2014-01-14 20:14:09 +00:00
parent a9f5c13d0c
commit 8ce7184bc2
9 changed files with 262 additions and 33 deletions
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47
src/vdbe.c
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@@ -3369,6 +3369,53 @@ case OP_OpenEphemeral: {
break;
}
/* Opcode: OpenEphreader P1 P2 * * *
**
** P2 is a cursor opened by the OpenEphemeral opcode. This opcode opens
** a new read-only cursor named P1 that accesses the same epheremal table
** as P2.
*/
case OP_OpenEphreader: {
VdbeCursor *pEph;
VdbeCursor *pCx;
Pgno pgno;
pEph = p->apCsr[pOp->p2];
pCx = allocateCursor(p, pOp->p1, pEph->nField, -1, 1);
if( pCx==0 ) goto no_mem;
pCx->nullRow = 1;
pCx->pKeyInfo = pEph->pKeyInfo;
pCx->isTable = pEph->isTable;
pCx->isOrdered = pEph->isOrdered;
pgno = MASTER_ROOT + !pCx->isTable;
rc = sqlite3BtreeCursor(pEph->pBt, pgno, 0, pCx->pKeyInfo, pCx->pCursor);
break;
}
/* Opcode: SwapCursors P1 P2 * * *
**
** Parameters P1 and P2 are both cursors opened by the OpenEphemeral
** opcode. This opcode deletes the contents of epheremal table P1,
** then renames P2 to P1 and P1 to P2. In other words, following this
** opcode cursor P2 is open on an empty table and P1 is open on the
** table that was initially accessed by P2.
*/
case OP_SwapCursors: {
Mem tmp;
VdbeCursor *pTmp;
tmp = p->aMem[p->nMem - pOp->p1];
p->aMem[p->nMem - pOp->p1] = p->aMem[p->nMem - pOp->p2];
p->aMem[p->nMem - pOp->p2] = tmp;
pTmp = p->apCsr[pOp->p1];
p->apCsr[pOp->p1] = p->apCsr[pOp->p2];
p->apCsr[pOp->p2] = pTmp;
rc = sqlite3BtreeClearTable(pTmp->pBt, MASTER_ROOT + !pTmp->isTable, 0);
break;
}
/* Opcode: SorterOpen P1 * * P4 *
**
** This opcode works like OP_OpenEphemeral except that it opens