diff options
Diffstat (limited to 'contrib')
| -rw-r--r-- | contrib/pg_visibility/pg_visibility.c | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/contrib/pg_visibility/pg_visibility.c b/contrib/pg_visibility/pg_visibility.c index 1a1a4ff7be7..adeb9512a70 100644 --- a/contrib/pg_visibility/pg_visibility.c +++ b/contrib/pg_visibility/pg_visibility.c @@ -380,6 +380,7 @@ pg_truncate_visibility_map(PG_FUNCTION_ARGS) Relation rel; ForkNumber fork; BlockNumber block; + BlockNumber old_block; rel = relation_open(relid, AccessExclusiveLock); @@ -389,15 +390,22 @@ pg_truncate_visibility_map(PG_FUNCTION_ARGS) /* Forcibly reset cached file size */ RelationGetSmgr(rel)->smgr_cached_nblocks[VISIBILITYMAP_FORKNUM] = InvalidBlockNumber; + /* Compute new and old size before entering critical section. */ + fork = VISIBILITYMAP_FORKNUM; block = visibilitymap_prepare_truncate(rel, 0); - if (BlockNumberIsValid(block)) - { - fork = VISIBILITYMAP_FORKNUM; - smgrtruncate(RelationGetSmgr(rel), &fork, 1, &block); - } + old_block = BlockNumberIsValid(block) ? smgrnblocks(RelationGetSmgr(rel), fork) : 0; + + /* + * WAL-logging, buffer dropping, file truncation must be atomic and all on + * one side of a checkpoint. See RelationTruncate() for discussion. + */ + Assert((MyProc->delayChkptFlags & (DELAY_CHKPT_START | DELAY_CHKPT_COMPLETE)) == 0); + MyProc->delayChkptFlags |= DELAY_CHKPT_START | DELAY_CHKPT_COMPLETE; + START_CRIT_SECTION(); if (RelationNeedsWAL(rel)) { + XLogRecPtr lsn; xl_smgr_truncate xlrec; xlrec.blkno = 0; @@ -407,9 +415,17 @@ pg_truncate_visibility_map(PG_FUNCTION_ARGS) XLogBeginInsert(); XLogRegisterData((char *) &xlrec, sizeof(xlrec)); - XLogInsert(RM_SMGR_ID, XLOG_SMGR_TRUNCATE | XLR_SPECIAL_REL_UPDATE); + lsn = XLogInsert(RM_SMGR_ID, + XLOG_SMGR_TRUNCATE | XLR_SPECIAL_REL_UPDATE); + XLogFlush(lsn); } + if (BlockNumberIsValid(block)) + smgrtruncate(RelationGetSmgr(rel), &fork, 1, &old_block, &block); + + END_CRIT_SECTION(); + MyProc->delayChkptFlags &= ~(DELAY_CHKPT_START | DELAY_CHKPT_COMPLETE); + /* * Release the lock right away, not at commit time. * |