Alvaro Herrera wrote:
Simon Riggs wrote:
On Wed, 2008-09-17 at 10:09 +0300, Heikki Linnakangas wrote:
Isn't autoanalyze a waste of time during a bulk load? Seems better to
run ANALYZE manually at the end.
Its not a waste of time because it catches tables immediately they have
been loaded, not just at the end of the bulk load. Running ANALYZE is a
waste of time if autoanalyze has already caught it, which is why that's
never been added onto the end of a pg_dump script. But currently this is
true only when we have both autoVACUUM and autoANALYZE enabled.
Hmm, one of the first complaints about defaulting autovacuum to on was
that it made restores so much longer *because* it was choosing to do
autoanalyzes on the tables as they were imported. It was then that the
auto-cancel mechanism was introduced.
http://pgsql.markmail.org/message/rqyjkafuw43426xy
Why doesn't this new request conflict with that one?
The problem back then was that a CREATE INDEX was waiting on the
autoanalyze to finish, and the autoanalyze took a long time to finish
because of vacuum_cost_delay. Now that we have the auto-cancel
mechanism, that's not a problem.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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