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There are some bugs about backward scanning using

Browse Source 
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
REL6_5_PATCHES
Bruce Momjian 27 years ago
parent df6e504437
commit 174b552e71
3 changed files with 102 additions and 22 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 72
      src/backend/access/nbtree/nbtsearch.c
  2. 10
      src/backend/access/nbtree/nbtutils.c
  3. 42
      src/backend/executor/nodeIndexscan.c

72
src/backend/access/nbtree/nbtsearch.c
Unescape 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
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@ -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
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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);

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