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Re: BUG #6426: Complex query runs 10 times longer with "LIMIT 20"

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andrew Schetinin <aschetinin(at)gmail(dot)com>
Cc: Alex Lai <alai(at)sesda2(dot)com>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #6426: Complex query runs 10 times longer with "LIMIT 20"
Date: 2012-02-01 21:48:35
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-bugs
Andrew Schetinin <aschetinin(at)gmail(dot)com> writes:
> In my specific case, what I've seen from the query execution plans, is that
> without LIMIT the query uses Hash Joins, but once I add LIMIT, it starts
> using Nested Loop Joins almost everywhere.

Usually, that's an appropriate change for a small LIMIT.  It's certainly
not a priori evidence of a planner bug.

If you want useful comments about this, please review
about how to provide an adequate description of your problem.

			regards, tom lane

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