Autovacuum behavior

From: John Scalia <jayknowsunix(at)gmail(dot)com>
To: "pgsql-admin(at)postgresql(dot)org" <pgsql-admin(at)postgresql(dot)org>
Subject: Autovacuum behavior
Date: 2015-07-30 18:49:46
Message-ID: CABzCKRDtMfmgKFoMeTFDRGif+siQK9bXM4791ii8ZBJfORSFNA@mail.gmail.com
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Hi all,

The autovacuum settings for a 9.4.2 database are shown below, I'm not
absolutely certain if I missed anything:

autovacuum = on
log_autovacuum_min_duration = 100
autovacuum_max_workers = 15
autovacuum_naptime = 10min
#autovacuum_vacuum_threshold = 50
autovacuum_analyze_threshold = 80
autovacuum_vacuum_scale_factor = 0.1
autovacuum_analyze_scale_factor = 0.2
autovacuum_freeze_max_age = 100000000
autovacuum_vacuum_cost_delay = 20ms
autovacuum_vacuum_cost_limit = -1
vacuum_freeze_min_age = 5000000
vacuum_freeze_table_age = 2500000

But, when I examine pg_stat_all_tables, I'm seeing a lot of tables where
n_dead_tup is still a lot greater than n_live_tup. Mind you, these are all
fairly small tables. I'm also seeing that the last_autovacuum ran about
11:22 AM CDT this morning.I would think the tables where there were no live
tuples and a bunch of dead_tuples would have been vacuumed after 11:22 AM
to clear the dead ones. Am I missing something?
--
Jay

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