Re: Looks like merge join planning time is too big, 55 seconds

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Sergey Burladyan <eshkinkot(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Looks like merge join planning time is too big, 55 seconds
Date: 2013-08-02 15:35:45
Message-ID: CAMkU=1yZvKht41LTrQB5UO7J=bO+beFLDLZ5E84_nRNLj20eRQ@mail.gmail.com
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On Fri, Aug 2, 2013 at 2:58 AM, Sergey Burladyan <eshkinkot(at)gmail(dot)com> wrote:
>
> PS: I think my main problem is here:
> select min(user_id) from items;
> min
> -----
> 1
> (1 row)
>
> Time: 504.520 ms

That is a long time, but still 100 fold less than the planner is taking.

What about max(user_id)?

>
> also, i cannot reindex it concurrently now, because it run autovacuum: VACUUM ANALYZE public.items (to prevent wraparound)

That is going to take a long time if you have the cost settings at
their defaults.

Cheers,

Jeff

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