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Initial implementation of an optimization that attempts to reuse the same

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materialization of a view on a self-join of the view.

FossilOrigin-Name: 478c34b9a8b5127d13024e10307aa832f160b89720c46424dd17555bd36f590d
This commit is contained in:
drh
2017-05-01 15:15:41 +00:00
parent 7555581fc1
commit e08e8d6b61
5 changed files with 69 additions and 13 deletions
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28
src/vdbe.c
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@@ -3540,6 +3540,34 @@ open_cursor_set_hints:
break;
}
/* Opcode: OpenDup P1 P2 * * *
**
** Open a new cursor P1 that points to the same ephemeral table as
** cursor P2. The P2 cursor must have been opened by a prior OP_OpenEphemeral
** opcode. Only ephemeral cursors may be duplicated.
**
** Duplicate ephemeral cursors are used for self-joins of materialized views.
*/
case OP_OpenDup: {
VdbeCursor *pOrig; /* The original cursor to be duplicated */
VdbeCursor *pCx; /* The new cursor */
pOrig = p->apCsr[pOp->p2];
assert( pOrig->pBtx!=0 ); /* Only ephemeral cursors can be duplicated */
pCx = allocateCursor(p, pOp->p1, pOrig->nField, -1, CURTYPE_BTREE);
if( pCx==0 ) goto no_mem;
pCx->nullRow = 1;
pCx->isEphemeral = 1;
pCx->pKeyInfo = pOrig->pKeyInfo;
pCx->isTable = pOrig->isTable;
rc = sqlite3BtreeCursor(pOrig->pBtx, MASTER_ROOT, BTREE_WRCSR,
pCx->pKeyInfo, pCx->uc.pCursor);
if( rc ) goto abort_due_to_error;
break;
}
/* Opcode: OpenEphemeral P1 P2 * P4 P5
** Synopsis: nColumn=P2
**