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pgstattuple: Use SnapshotDirty, not SnapshotNow. 

Tuples belonging to uncommitted transactions should not be
counted as dead.

This is arguably a bug fix that should be back-patched, but
as no one ever noticed until it came time to try to get rid
of SnapshotNow, I'm only doing this in master for now.
This commit is contained in:
Robert Haas 2013-07-25 16:16:42 -04:00
parent 3483f4332d
commit 80c79ab2a8
1 changed files with 3 additions and 1 deletions
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4
contrib/pgstattuple/pgstattuple.c
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@ -278,9 +278,11 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
Buffer buffer;
pgstattuple_type stat = {0};
BufferAccessStrategy bstrategy;
SnapshotData SnapshotDirty;
/* Disable syncscan because we assume we scan from block zero upwards */
scan = heap_beginscan_strat(rel, SnapshotAny, 0, NULL, true, false);
InitDirtySnapshot(SnapshotDirty);
nblocks = scan->rs_nblocks; /* # blocks to be scanned */
@ -296,7 +298,7 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
/* must hold a buffer lock to call HeapTupleSatisfiesVisibility */
LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
if (HeapTupleSatisfiesVisibility(tuple, SnapshotNow, scan->rs_cbuf))
if (HeapTupleSatisfiesVisibility(tuple, &SnapshotDirty, scan->rs_cbuf))
{
stat.tuple_len += tuple->t_len;
stat.tuple_count++;