Re: pg_autovacuum and VACUUM FREEZE

From: Christopher Browne <cbbrowne(at)acm(dot)org>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: pg_autovacuum and VACUUM FREEZE
Date: 2003-10-21 02:54:48
Message-ID: m3n0bvz4ef.fsf@wolfe.cbbrowne.com
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I just ran into a new little anomaly in pg_autovacuum...

Note the interesting _negative_ numbers. Apparently something's
rolling over. I have no _grand_ problem with what happened, namely
"immediately checking again," as the system in question was doing
heavy offline updates. But this is likely to be pretty adverse on
other systems where this could turn into a pathological situation of
vacuuming when the system has already been VERY busy from vacuuming
some really big tables.

[Names of objects changed to protect the not-so-innocent :-)]

[2003-10-20 06:05:48 PM] Performing: VACUUM ANALYZE "public"."my_enormous_table"
[2003-10-20 08:13:23 PM] table name:
anonymous_database."public"."my_enormous_table"
[2003-10-20 08:13:23 PM] relfilenode: 542631733; relisshared: 0
[2003-10-20 08:13:23 PM] reltuples: 5; relpages: 128332
[2003-10-20 08:13:23 PM] curr_analyze_count: 959974;
cur_delete_count: 959974
[2003-10-20 08:13:23 PM] ins_at_last_analyze: 959974;
del_at_last_vacuum: 959974
[2003-10-20 08:13:23 PM] insert_threshold: 505;
delete_threshold 10010
[2003-10-20 08:13:23 PM] 2 All DBs checked in: -934428113 usec, will
sleep for -3872 secs.
[2003-10-20 08:13:23 PM] updating the database list
[2003-10-20 08:13:23 PM] Performing: VACUUM ANALYZE "public"."my_enormous_table"
[2003-10-20 08:52:39 PM] table name:
anonymous_database."public"."my_enormous_table"
[2003-10-20 08:52:39 PM] relfilenode: 542631733; relisshared: 0
[2003-10-20 08:52:39 PM] reltuples: 5; relpages: 164343
[2003-10-20 08:52:39 PM] curr_analyze_count: 4097974;
cur_delete_count: 4097974
[2003-10-20 08:52:39 PM] ins_at_last_analyze: 4097974;
del_at_last_vacuum: 4097974
[2003-10-20 08:52:39 PM] insert_threshold: 505;
delete_threshold 10010
[2003-10-20 08:52:39 PM] 3 All DBs checked in: -1938733385 usec, will
sleep for -8893 secs.
[2003-10-20 08:52:39 PM] Performing: VACUUM ANALYZE "public"."my_enormous_table"
[2003-10-20 09:00:07 PM] table name:
anonymous_database."public"."my_enormous_table"
[2003-10-20 09:00:07 PM] relfilenode: 542631733; relisshared: 0
[2003-10-20 09:00:07 PM] reltuples: 6; relpages: 164343
[2003-10-20 09:00:07 PM] curr_analyze_count: 4661974;
cur_delete_count: 4661974
[2003-10-20 09:00:07 PM] ins_at_last_analyze: 4661974;
del_at_last_vacuum: 4661974
[2003-10-20 09:00:07 PM] insert_threshold: 506;
delete_threshold 10012
[2003-10-20 09:00:07 PM] 4 All DBs checked in: 448475756 usec, will
sleep for 3042 secs.
--
let name="aa454" and tld="freenet.carleton.ca" in name ^ "@" ^ tld;;
http://www.ntlug.org/~cbbrowne/spreadsheets.html
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-- Marvin the Paranoid Android

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