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I have a table with about 15 million rows which is constantly having tuples added to the head and deleted in blocks from the tail to maintain the size. The dead tuple count in pg_stat_user_tables tracks the deleted rows fairly accurately until an auto-ANALYZE is done in the background at which point the value it calculates is wrong by a factor of 2-3 times (calculated value is 30-50% of the correct value), which completely throws the auto-VACUUMing. An example is that the auto-VACUUM only ran when there were 12 million (real) dead rows! Any ideas?
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ANALYZE getting dead tuple count hopelessly wrong
- From: Stuart Brooks <stuartb(at)cat(dot)co(dot)za>
- To: pgsql-general(at)postgresql(dot)org
- Subject: ANALYZE getting dead tuple count hopelessly wrong
- Date: Mon, 31 Mar 2008 10:03:23 +0200
I have a table with about 15 million rows which is constantly having tuples added to the head and deleted in blocks from the tail to maintain the size. The dead tuple count in pg_stat_user_tables tracks the deleted rows fairly accurately until an auto-ANALYZE is done in the background at which point the value it calculates is wrong by a factor of 2-3 times (calculated value is 30-50% of the correct value), which completely throws the auto-VACUUMing. An example is that the auto-VACUUM only ran when there were 12 million (real) dead rows! Any ideas?
Thanks Stuart PS. Running 8.3.1 on NetBSD 3.
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