From: Tom Lane <tgl@sss.pgh.pa.us>
To: plukovic <petar@sobot.biz>
cc: pgsql-performance@postgresql.org
Subject: Re: Speed differences between in executing the same query
In-reply-to: <1494510842628-5960964.post@n3.nabble.com>
References: <1494510842628-5960964.post@n3.nabble.com>
Comments: In-reply-to plukovic <petar@sobot.biz>
	message dated "Thu, 11 May 2017 06:54:02 -0700"
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Date: Thu, 11 May 2017 10:06:58 -0400
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plukovic <petar@sobot.biz> writes:
> I have a weird case of query execution performance here.

My first thought is that you are getting a bad plan because of this
estimation error:

>                     ->  Index Scan using uk_TBL_sk0_account_code on TBL_sk
> sk2_  (cost=0.14..12.53 rows=1 width=426) (actual time=1.036..1.084 rows=50
> loops=1)
>                           Index Cond: (acco_id = 1)

That rowcount estimate is off by 50X, resulting in 50X errors for the
joins above it too, and in misguided choices of nestloops when some
other join method would be better.  Probably things would improve with
a better estimate.  Maybe you need to increase the stats target for
that table ... or maybe it just hasn't been ANALYZEd lately?

			regards, tom lane


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