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> > Prevent sorting if result is already sorted

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> >
> > was implemented by Jan Wieck.
> > His work is for ascending order cases.
> >
> > Here is a patch to prevent sorting also in descending
> > order cases.
> > Because I had already changed _bt_first() to position
> > backward correctly before v6.5,this patch would work.
> >
Hiroshi Inoue
Inoue@tpf.co.jp
This commit is contained in:
Bruce Momjian
1999-08-09 06:20:27 +00:00
parent 5efe31214a
commit 158fd5f1c4
9 changed files with 78 additions and 28 deletions
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13
src/backend/executor/nodeIndexscan.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.40 1999/07/16 04:58:50 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.41 1999/08/09 06:20:22 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -99,6 +99,13 @@ IndexNext(IndexScan *node)
*/
estate = node->scan.plan.state;
direction = estate->es_direction;
if (ScanDirectionIsBackward(node->indxorderdir))
{
if (ScanDirectionIsForward(direction))
direction = BackwardScanDirection;
else if (ScanDirectionIsBackward(direction))
direction = ForwardScanDirection;
}
snapshot = estate->es_snapshot;
scanstate = node->scan.scanstate;
indexstate = node->indxstate;
@ -316,6 +323,8 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan *parent)
indxqual = node->indxqual;
numScanKeys = indexstate->iss_NumScanKeys;
indexstate->iss_IndexPtr = -1;
if (ScanDirectionIsBackward(node->indxorderdir))
indexstate->iss_IndexPtr = numIndices;
/* If this is re-scanning of PlanQual ... */
if (estate->es_evTuple != NULL &&
@ -966,6 +975,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
}
indexstate->iss_NumIndices = numIndices;
if (ScanDirectionIsBackward(node->indxorderdir))
indexPtr = numIndices;
indexstate->iss_IndexPtr = indexPtr;
indexstate->iss_ScanKeys = scanKeys;
indexstate->iss_NumScanKeys = numScanKeys;