Re: Multi-pass planner

From: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
To: Claudio Freire <klaussfreire(at)gmail(dot)com>
Cc: Greg Stark <stark(at)mit(dot)edu>, decibel <decibel(at)decibel(dot)org>, Josh Berkus <josh(at)agliodbs(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Multi-pass planner
Date: 2013-04-19 22:43:27
Message-ID: CAMkU=1wnmcZOX3B9Qy79qtVvAr9hx=VvxVZOB-B0C82B_ZPdng@mail.gmail.com
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On Fri, Apr 19, 2013 at 2:24 PM, Claudio Freire <klaussfreire(at)gmail(dot)com>wrote:

>
> Especially if there's some locality of occurrence, since analyze
> samples pages, not rows.
>

But it doesn't take all rows in each sampled page. It generally takes
about one row per page, specifically to avoid the problem you indicate.
Maybe it is possible to trick it into taking too many (for example, if most
pages are completely empty), but I haven't experienced that as being a
problem.

Cheers,

Jeff

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