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Commitc79f6df

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Do index FSM vacuuming sooner.
In btree and SP-GiST indexes, move the responsibility for callingIndexFreeSpaceMapVacuum from the vacuumcleanup phase to the bulkdeletephase, and do it if and only if we found some pages that could be put intoFSM. As in commit851a26e, the idea is to make free pages visible to FSMsearchers sooner when vacuuming very large tables (large enough to needmultiple bulkdelete scans). This adds more redundant work than that commitdid, since we have to scan the entire index FSM each time rather than beingable to localize what needs to be updated; but it still seems worthwhile.However, we can buy something back by not touching the FSM at all whenthere are no pages that can be put in it. That will result in slowerrecovery from corrupt upper FSM pages in such a scenario, but it doesn'tseem like that's a case we need to optimize for.Hash indexes don't use FSM at all. GIN, GiST, and bloom indexes updateFSM during the vacuumcleanup phase not bulkdelete, so that doing somethingcomparable to this would be a much more invasive change, and it's not clearit's worth it. BRIN indexes do things sufficiently differently that thischange doesn't apply to them, either.Claudio Freire, reviewed by Masahiko Sawada and Jing Wang, some additionaltweaks by meDiscussion:https://postgr.es/m/CAGTBQpYR0uJCNTt3M5GOzBRHo+-GccNO1nCaQ8yEJmZKSW5q1A@mail.gmail.com
1 parent96030f9 commitc79f6df

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2 files changed

+32
-9
lines changed

2 files changed

+32
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lines changed

‎src/backend/access/nbtree/nbtree.c

Lines changed: 15 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -832,9 +832,6 @@ btvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
832832
btvacuumscan(info,stats,NULL,NULL,0);
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}
834834

835-
/* Finally, vacuum the FSM */
836-
IndexFreeSpaceMapVacuum(info->index);
837-
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/*
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* It's quite possible for us to be fooled by concurrent page splits into
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* double-counting some index tuples, so disbelieve any total that exceeds
@@ -976,6 +973,21 @@ btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
976973

977974
MemoryContextDelete(vstate.pagedelcontext);
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976+
/*
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* If we found any recyclable pages (and recorded them in the FSM), then
978+
* forcibly update the upper-level FSM pages to ensure that searchers can
979+
* find them. It's possible that the pages were also found during
980+
* previous scans and so this is a waste of time, but it's cheap enough
981+
* relative to scanning the index that it shouldn't matter much, and
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* making sure that free pages are available sooner not later seems
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* worthwhile.
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*
985+
* Note that if no recyclable pages exist, we don't bother vacuuming the
986+
* FSM at all.
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*/
988+
if (vstate.totFreePages>0)
989+
IndexFreeSpaceMapVacuum(rel);
990+
979991
/* update statistics */
980992
stats->num_pages=num_pages;
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stats->pages_free=vstate.totFreePages;

‎src/backend/access/spgist/spgvacuum.c

Lines changed: 17 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -845,6 +845,21 @@ spgvacuumscan(spgBulkDeleteState *bds)
845845
/* Propagate local lastUsedPage cache to metablock */
846846
SpGistUpdateMetaPage(index);
847847

848+
/*
849+
* If we found any empty pages (and recorded them in the FSM), then
850+
* forcibly update the upper-level FSM pages to ensure that searchers can
851+
* find them. It's possible that the pages were also found during
852+
* previous scans and so this is a waste of time, but it's cheap enough
853+
* relative to scanning the index that it shouldn't matter much, and
854+
* making sure that free pages are available sooner not later seems
855+
* worthwhile.
856+
*
857+
* Note that if no empty pages exist, we don't bother vacuuming the FSM at
858+
* all.
859+
*/
860+
if (bds->stats->pages_deleted>0)
861+
IndexFreeSpaceMapVacuum(index);
862+
848863
/*
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* Truncate index if possible
850865
*
@@ -916,7 +931,6 @@ dummy_callback(ItemPointer itemptr, void *state)
916931
IndexBulkDeleteResult*
917932
spgvacuumcleanup(IndexVacuumInfo*info,IndexBulkDeleteResult*stats)
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{
919-
Relationindex=info->index;
920934
spgBulkDeleteStatebds;
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922936
/* No-op in ANALYZE ONLY mode */
@@ -926,8 +940,8 @@ spgvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
926940
/*
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* We don't need to scan the index if there was a preceding bulkdelete
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* pass. Otherwise, make a pass that won't delete any live tuples, but
929-
* might still accomplish useful stuff with redirect/placeholder cleanup,
930-
* and in any case will provide stats.
943+
* might still accomplish useful stuff with redirect/placeholder cleanup
944+
* and/or FSM housekeeping, and in any case will provide stats.
931945
*/
932946
if (stats==NULL)
933947
{
@@ -940,9 +954,6 @@ spgvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
940954
spgvacuumscan(&bds);
941955
}
942956

943-
/* Finally, vacuum the FSM */
944-
IndexFreeSpaceMapVacuum(index);
945-
946957
/*
947958
* It's quite possible for us to be fooled by concurrent tuple moves into
948959
* double-counting some index tuples, so disbelieve any total that exceeds

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