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Separate TBM[Shared|Private]Iterator and TBMIterateResult

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Remove the TBMIterateResult member from the TBMPrivateIterator and
TBMSharedIterator and make tbm_[shared|private_]iterate() take a
TBMIterateResult as a parameter.

This allows tidbitmap API users to manage multiple TBMIterateResults per
scan. This is required for bitmap heap scan to use the read stream API,
with which there may be multiple I/Os in flight at once, each one with a
TBMIterateResult.

Reviewed-by: Tomas Vondra <tomas@vondra.me>
Discussion: https://postgr.es/m/d4bb26c9-fe07-439e-ac53-c0e244387e01%40vondra.me
This commit is contained in:
Melanie Plageman
2025-03-15 10:10:51 -04:00
parent 799959dc7c
commit 944e81bf99
7 changed files with 110 additions and 101 deletions
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39
src/backend/executor/nodeBitmapHeapscan.c
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@@ -317,7 +317,7 @@ BitmapAdjustPrefetchIterator(BitmapHeapScanState *node)
{
#ifdef USE_PREFETCH
ParallelBitmapHeapState *pstate = node->pstate;
TBMIterateResult *tbmpre;
TBMIterateResult tbmpre;
if (pstate == NULL)
{
@@ -330,9 +330,8 @@ BitmapAdjustPrefetchIterator(BitmapHeapScanState *node)
}
else if (!tbm_exhausted(prefetch_iterator))
{
tbmpre = tbm_iterate(prefetch_iterator);
node->prefetch_blockno = tbmpre ? tbmpre->blockno :
InvalidBlockNumber;
tbm_iterate(prefetch_iterator, &tbmpre);
node->prefetch_blockno = tbmpre.blockno;
}
return;
}
@@ -371,9 +370,8 @@ BitmapAdjustPrefetchIterator(BitmapHeapScanState *node)
*/
if (!tbm_exhausted(prefetch_iterator))
{
tbmpre = tbm_iterate(prefetch_iterator);
node->prefetch_blockno = tbmpre ? tbmpre->blockno :
InvalidBlockNumber;
tbm_iterate(prefetch_iterator, &tbmpre);
node->prefetch_blockno = tbmpre.blockno;
}
}
}
@@ -441,17 +439,18 @@ BitmapPrefetch(BitmapHeapScanState *node, TableScanDesc scan)
{
while (node->prefetch_pages < node->prefetch_target)
{
TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);
TBMIterateResult tbmpre;
bool skip_fetch;
if (tbmpre == NULL)
if (!tbm_iterate(prefetch_iterator, &tbmpre))
{
/* No more pages to prefetch */
Assert(!BlockNumberIsValid(tbmpre.blockno));
tbm_end_iterate(prefetch_iterator);
break;
}
node->prefetch_pages++;
node->prefetch_blockno = tbmpre->blockno;
node->prefetch_blockno = tbmpre.blockno;
/*
* If we expect not to have to actually read this heap page,
@@ -460,13 +459,13 @@ BitmapPrefetch(BitmapHeapScanState *node, TableScanDesc scan)
* prefetch_pages?)
*/
skip_fetch = (!(scan->rs_flags & SO_NEED_TUPLES) &&
!tbmpre->recheck &&
!tbmpre.recheck &&
VM_ALL_VISIBLE(node->ss.ss_currentRelation,
tbmpre->blockno,
tbmpre.blockno,
&node->pvmbuffer));
if (!skip_fetch)
PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre->blockno);
PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre.blockno);
}
}
@@ -481,7 +480,7 @@ BitmapPrefetch(BitmapHeapScanState *node, TableScanDesc scan)
{
while (1)
{
TBMIterateResult *tbmpre;
TBMIterateResult tbmpre;
bool do_prefetch = false;
bool skip_fetch;
@@ -500,25 +499,25 @@ BitmapPrefetch(BitmapHeapScanState *node, TableScanDesc scan)
if (!do_prefetch)
return;
tbmpre = tbm_iterate(prefetch_iterator);
if (tbmpre == NULL)
if (!tbm_iterate(prefetch_iterator, &tbmpre))
{
Assert(!BlockNumberIsValid(tbmpre.blockno));
/* No more pages to prefetch */
tbm_end_iterate(prefetch_iterator);
break;
}
node->prefetch_blockno = tbmpre->blockno;
node->prefetch_blockno = tbmpre.blockno;
/* As above, skip prefetch if we expect not to need page */
skip_fetch = (!(scan->rs_flags & SO_NEED_TUPLES) &&
!tbmpre->recheck &&
!tbmpre.recheck &&
VM_ALL_VISIBLE(node->ss.ss_currentRelation,
tbmpre->blockno,
tbmpre.blockno,
&node->pvmbuffer));
if (!skip_fetch)
PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre->blockno);
PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre.blockno);
}
}
}