Re: autovacuum and temp tables support
Oleg Bartunov <oleg@sai.msu.su>
From: Oleg Bartunov <oleg@sai.msu.su>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Alvaro Herrera <alvherre@commandprompt.com>, Pgsql Hackers <pgsql-hackers@postgresql.org>
Date: 2010-04-08T19:22:08Z
Lists: pgsql-hackers
On Thu, 8 Apr 2010, Robert Haas wrote: > On Thu, Apr 8, 2010 at 2:53 PM, Alvaro Herrera > <alvherre@commandprompt.com> wrote: >> Oleg Bartunov wrote: >> >>> our client complained about slow query, which involves temporary tables. >>> Analyzing them manually solved the problem. I don't remember >>> arguments against temporary tables support by autovacuum. I'd >>> appreciate any >>> pointers. >> >> Autovacuum can't process temp tables; they could reside in a backend's >> private temp buffers (local memory, not shared). > > On general thought I've had is that it would be nice if the first > attempt to SELECT against a table with no statistics would trigger an > automatic ANALYZE by the backend on which the query was executed. > It's pretty common to populate a table using INSERT, or CTAS, or COPY > and then try to immediately run a query against it, and I've often > found that it's necessary to insert manual analyze statements in there > to get decent query plans. Oracle does this. So, is't worth to add support (configurable, like Oracle's optimizer_dynamic_sampling) ? Regards, Oleg _____________________________________________________________ Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru), Sternberg Astronomical Institute, Moscow University, Russia Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/ phone: +007(495)939-16-83, +007(495)939-23-83