Count locked pages that don't need vacuuming as scanned.

hlinnaka · hlinnaka · commit 3379263b6ded · 2013-11-18T10:12:22.000+02:00
Previously, if VACUUM skipped vacuuming a page because it's pinned, it
didn't count that page as scanned. However, that meant that relfrozenxid
was not bumped up either, which prevented anti-wraparound vacuum from
doing its job.

Report by Миша Тюрин, analysis and patch by Sergey Burladyn and Jeff Janes.
Backpatch to 9.2, where the skip-locked-pages behavior was introduced.
diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
@@ -589,6 +589,7 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
 			if (!lazy_check_needs_freeze(buf))
 			{
 				UnlockReleaseBuffer(buf);
+				vacrelstats->scanned_pages++;
 				continue;
 			}
 			LockBuffer(buf, BUFFER_LOCK_UNLOCK);

Original file line number	Diff line number	Diff line change
`@@ -589,6 +589,7 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,`
`589`	`589`	`if (!lazy_check_needs_freeze(buf))`
`590`	`590`	`{`
`591`	`591`	`UnlockReleaseBuffer(buf);`
	`592`	`+ vacrelstats->scanned_pages++;`
`592`	`593`	`continue;`
`593`	`594`	`}`
`594`	`595`	`LockBuffer(buf, BUFFER_LOCK_UNLOCK);`