Database-wide vacuum can take a long time, during which tables are not being analyzed

From: "Steven Flatt" <steven(dot)flatt(at)gmail(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Database-wide vacuum can take a long time, during which tables are not being analyzed
Date: 2006-11-01 19:15:29
Message-ID: 357fa7590611011115q748ddce9qa6cf570ec2f15348@mail.gmail.com
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Here is a potential problem with the auto-vacuum daemon, and I'm wondering
if anyone has considered this. To avoid transaction ID wraparound, the
auto-vacuum daemon will periodically determine that it needs to do a DB-wide
vacuum, which takes a long time. On our system, it is on the order of a
couple of weeks. (The system is very busy and there is a lot of I/O going
on pretty much 24/7). During this period of time, there is nothing to
automatically analyze any of the tables, leading to further performance
problems. What are your thoughts on having the DB-wide vacuum running on a
separate thread so that the daemon can concurrently wake up and take care of
analyzing tables?

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