From: Tom Lane <tgl@sss.pgh.pa.us>
To: Rural Hunter <ruralhunter@gmail.com>
cc: pgsql-performance@postgresql.org
Subject: Re: Very slow planning performance on partition table
In-reply-to: <53CFB6BC.4050606@gmail.com>
References: <53CFB6BC.4050606@gmail.com>
Comments: In-reply-to Rural Hunter <ruralhunter@gmail.com>
 message dated "Wed, 23 Jul 2014 21:21:00 +0800"
Date: Thu, 24 Jul 2014 21:53:23 -0400
Message-ID: <25010.1406253203@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-performance-owner@postgresql.org

Rural Hunter <ruralhunter@gmail.com> writes:
> I have a table partitioned with about 60 children tables.  Now I found 
> the planning time of simple query with partition key are very slow.
> ...
> You can see the timing output that the actual run time of the 'explain 
> analyze' is 30 seconds while the select sql itself takes only 3 ms. My 
> partition key is on article.pid and the constraint is simple like this: 
> CONSTRAINT article_88_pid_check CHECK (pid = 88). What's wrong and how 
> can I improve the planning performance?

[ shrug... ] Insufficient data.  When I try a simple test case based on
what you've told us, I get planning times of a couple of milliseconds.
I can think of contributing factors that would increase that, but not by
four orders of magnitude.  So there's something very significant that
you've left out.  Can you construct a self-contained test case that's
this slow?

			regards, tom lane


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