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Re: Massive memory use for star query

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: Massive memory use for star query
Date: 2011-04-15 16:43:01
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Lists: pgsql-bugs
Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz> writes:
> I've recently seen examples of star-like queries using vast amounts of 
> memory in one of our production systems. Here's a simplified example 
> using synthetic data (see attached to generate if desired):

> SET geqo_threshold = 14;
> SET from_collapse_limit = 14;
> SET join_collapse_limit = 14;

Well, if you're going to do the above, you should be expecting the
planner to eat a lot of memory.  There is a reason why the default
values of those parameters are significantly lower than that ...

			regards, tom lane

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