From: Heikki Linnakangas Date: Tue, 6 Jan 2009 14:56:13 +0000 (+0000) Subject: Fix logic in lazy vacuum to decide if it's worth trying to truncate the heap. X-Git-Tag: REL7_4_24~10 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4d79a504942d7e3f58133bc56087137091f3a5b7;p=postgresql Fix logic in lazy vacuum to decide if it's worth trying to truncate the heap. If the table was smaller than REL_TRUNCATE_FRACTION (= 16) pages, we always tried to acquire AccessExclusiveLock on it even if there was no empty pages at the end. Report by Simon Riggs. Back-patch all the way to 7.4. --- diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c index 732c6d4bf9..d7daf1ba3c 100644 --- a/src/backend/commands/vacuumlazy.c +++ b/src/backend/commands/vacuumlazy.c @@ -31,7 +31,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/commands/vacuumlazy.c,v 1.32.2.2 2007/09/16 02:38:25 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/commands/vacuumlazy.c,v 1.32.2.3 2009/01/06 14:56:13 heikki Exp $ * *------------------------------------------------------------------------- */ @@ -161,8 +161,9 @@ lazy_vacuum_rel(Relation onerel, VacuumStmt *vacstmt) * number of pages. Otherwise, the time taken isn't worth it. */ possibly_freeable = vacrelstats->rel_pages - vacrelstats->nonempty_pages; - if (possibly_freeable >= REL_TRUNCATE_MINIMUM || - possibly_freeable >= vacrelstats->rel_pages / REL_TRUNCATE_FRACTION) + if (possibly_freeable > 0 && + (possibly_freeable >= REL_TRUNCATE_MINIMUM || + possibly_freeable >= vacrelstats->rel_pages / REL_TRUNCATE_FRACTION)) lazy_truncate_heap(onerel, vacrelstats); /* Update shared free space map with final free space info */