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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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

72
src/backend/access/nbtree/nbtsearch.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.42 1999/03/28 20:31:58 vadim Exp $
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.43 1999/04/13 17:18:28 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -733,7 +733,8 @@ _bt_next(IndexScanDesc scan, ScanDirection dir)
return res;
}
} while (keysok >= so->numberOfFirstKeys);
} while (keysok >= so->numberOfFirstKeys ||
(keysok == -1 && ScanDirectionIsBackward(dir)));
ItemPointerSetInvalid(current);
so->btso_curbuf = InvalidBuffer;
@ -775,6 +776,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
BTScanOpaque so;
ScanKeyData skdata;
Size keysok;
int i;
int nKeyIndex = -1;
rel = scan->relation;
so = (BTScanOpaque) scan->opaque;
@ -790,11 +793,34 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
{
_bt_orderkeys(rel, so);
strat = _bt_getstrat(rel, 1, so->keyData[0].sk_procedure);
if (ScanDirectionIsBackward(dir))
{
for (i=0; i<so->numberOfKeys; i++)
{
if (so->keyData[i].sk_attno != 1)
break;
strat = _bt_getstrat(rel, so->keyData[i].sk_attno,
so->keyData[i].sk_procedure);
if (strat == BTLessStrategyNumber ||
strat == BTLessEqualStrategyNumber||
strat == BTEqualStrategyNumber)
{
nKeyIndex = i;
break;
}
}
}
else
{
strat = _bt_getstrat(rel, 1, so->keyData[0].sk_procedure);
/* NOTE: it assumes ForwardScanDirection */
if (strat == BTLessStrategyNumber ||
strat == BTLessEqualStrategyNumber)
if (strat == BTLessStrategyNumber ||
strat == BTLessEqualStrategyNumber)
;
else
nKeyIndex = 0;
}
if (nKeyIndex < 0)
scan->scanFromEnd = true;
}
else
@ -823,8 +849,8 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
return (RetrieveIndexResult) NULL;
}
proc = index_getprocid(rel, 1, BTORDER_PROC);
ScanKeyEntryInitialize(&skdata, so->keyData[0].sk_flags, 1, proc,
so->keyData[0].sk_argument);
ScanKeyEntryInitialize(&skdata, so->keyData[nKeyIndex].sk_flags,
1, proc, so->keyData[nKeyIndex].sk_argument);
stack = _bt_search(rel, 1, &skdata, &buf);
_bt_freestack(stack);
@ -897,7 +923,7 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
/* it's yet other place to add some code latter for is(not)null */
strat = _bt_getstrat(rel, 1, so->keyData[0].sk_procedure);
strat = _bt_getstrat(rel, 1, so->keyData[nKeyIndex].sk_procedure);
switch (strat)
{
@ -914,9 +940,6 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
result = _bt_compare(rel, itupdesc, page, 1, &skdata, offnum);
} while (result <= 0);
/* if this is true, the key we just looked at is gone */
if (result > 0)
_bt_twostep(scan, &buf, ForwardScanDirection);
}
break;
@ -946,6 +969,21 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
ItemPointerSetInvalid(&(scan->currentItemData));
return (RetrieveIndexResult) NULL;
}
else if (ScanDirectionIsBackward(dir))
{
do
{
if (!_bt_twostep(scan, &buf, ForwardScanDirection))
break;
offnum = ItemPointerGetOffsetNumber(current);
page = BufferGetPage(buf);
result = _bt_compare(rel, itupdesc, page, 1, &skdata, offnum);
} while (result == 0);
if (result < 0)
_bt_twostep(scan, &buf, BackwardScanDirection);
}
break;
case BTGreaterEqualStrategyNumber:
@ -1026,6 +1064,11 @@ _bt_first(IndexScanDesc scan, ScanDirection dir)
so->btso_curbuf = buf;
return _bt_next(scan, dir);
}
else if (keysok == -1 && ScanDirectionIsBackward(dir))
{
so->btso_curbuf = buf;
return _bt_next(scan, dir);
}
else
{
ItemPointerSetInvalid(current);
@ -1495,6 +1538,11 @@ _bt_endpoint(IndexScanDesc scan, ScanDirection dir)
so->btso_curbuf = buf;
return _bt_next(scan, dir);
}
else if (keysok == -1 && ScanDirectionIsBackward(dir))
{
so->btso_curbuf = buf;
return _bt_next(scan, dir);
}
else
{
ItemPointerSetInvalid(current);

10
src/backend/access/nbtree/nbtutils.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.25 1999/02/13 23:14:37 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.26 1999/04/13 17:18:29 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -367,8 +367,14 @@ _bt_checkkeys(IndexScanDesc scan, IndexTuple tuple, Size *keysok)
&isNull);
/* btree doesn't support 'A is null' clauses, yet */
if (isNull || key[0].sk_flags & SK_ISNULL)
if (key[0].sk_flags & SK_ISNULL)
return false;
if (isNull)
{
if (*keysok < so->numberOfFirstKeys)
*keysok = -1;
return false;
}
if (key[0].sk_flags & SK_COMMUTE)
{

42
src/backend/executor/nodeIndexscan.c
View File

@ -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);