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There are some bugs about backward scanning using

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indexes.

1. Index Scan using plural indexids never scan backward
   as to the order of indexids.
2. The cursor using Index scan is not usable after moving
   past the end.

This patch solves above bugs.
Moreover the change of _bt_first() would be useful to extend
ORDER BY patch by Jan Wieck for all descending order cases.

Hiroshi Inoue
This commit is contained in:
Bruce Momjian
1999-04-13 17:18:29 +00:00
parent df6e504437
commit 174b552e71
3 changed files with 102 additions and 22 deletions
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42
src/backend/executor/nodeIndexscan.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.33 1999/02/21 03:48:40 scrappy Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.34 1999/04/13 17:18:29 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -96,6 +96,8 @@ IndexNext(IndexScan *node)
Buffer buffer = InvalidBuffer;
int numIndices;
bool bBackward;
int indexNumber;
/* ----------------
* extract necessary information from index scan node
* ----------------
@ -151,8 +153,26 @@ IndexNext(IndexScan *node)
* appropriate heap tuple.. else return NULL.
* ----------------
*/
while (indexstate->iss_IndexPtr < numIndices)
{
bBackward = ScanDirectionIsBackward(direction);
if (bBackward)
{
indexNumber = numIndices - indexstate->iss_IndexPtr - 1;
if (indexNumber < 0)
{
indexNumber = 0;
indexstate->iss_IndexPtr = numIndices - 1;
}
}
else
{
if ((indexNumber = indexstate->iss_IndexPtr) < 0)
{
indexNumber = 0;
indexstate->iss_IndexPtr = 0;
}
}
while (indexNumber < numIndices)
{
scandesc = scanDescs[indexstate->iss_IndexPtr];
while ((result = index_getnext(scandesc, direction)) != NULL)
{
@ -204,8 +224,14 @@ IndexNext(IndexScan *node)
if (BufferIsValid(buffer))
ReleaseBuffer(buffer);
}
if (indexstate->iss_IndexPtr < numIndices)
indexstate->iss_IndexPtr++;
if (indexNumber < numIndices)
{
indexNumber++;
if (bBackward)
indexstate->iss_IndexPtr--;
else
indexstate->iss_IndexPtr++;
}
}
/* ----------------
* if we get here it means the index scan failed so we
@ -294,7 +320,7 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan *parent)
runtimeKeyInfo = (Pointer *) indexstate->iss_RuntimeKeyInfo;
indxqual = node->indxqual;
numScanKeys = indexstate->iss_NumScanKeys;
indexstate->iss_IndexPtr = 0;
indexstate->iss_IndexPtr = -1;
/* If this is re-scanning of PlanQual ... */
if (estate->es_evTuple != NULL &&
@ -611,7 +637,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
*/
indexstate = makeNode(IndexScanState);
indexstate->iss_NumIndices = 0;
indexstate->iss_IndexPtr = 0;
indexstate->iss_IndexPtr = -1;
indexstate->iss_ScanKeys = NULL;
indexstate->iss_NumScanKeys = NULL;
indexstate->iss_RuntimeKeyInfo = NULL;
@ -635,7 +661,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
indxid = node->indxid;
indxqual = node->indxqual;
numIndices = length(indxid);
indexPtr = 0;
indexPtr = -1;
CXT1_printf("ExecInitIndexScan: context is %d\n", CurrentMemoryContext);