Re: 9.6 query slower than 9.5.3

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Adam Brusselback <adambrusselback(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: 9.6 query slower than 9.5.3
Date: 2016-06-17 02:04:25
Message-ID: 21539.1466129065@sss.pgh.pa.us
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Adam Brusselback <adambrusselback(at)gmail(dot)com> writes:
> Hey all, testing out 9.6 beta 1 right now on Debian 8.5.
> I have a query that is much slower on 9.6 than 9.5.3.

The rowcount estimates in 9.6 seem way off. Did you ANALYZE the tables
after loading them into 9.6? Maybe you forgot some statistics target
settings?

If it's not that, I wonder whether the misestimates are connected to the
foreign-key-based estimation feature. Are there any FKs on the tables
involved? May we see the table schemas?

regards, tom lane

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