Re: ANALYZE sampling is too good

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Greg Stark <stark(at)mit(dot)edu>
Cc: Peter Geoghegan <pg(at)heroku(dot)com>, Jim Nasby <jim(at)nasby(dot)net>, Josh Berkus <josh(at)agliodbs(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: ANALYZE sampling is too good
Date: 2013-12-11 00:40:08
Message-ID: CA+U5nMJ+kp_xhV8LSSOG_ekTBRvD5YMYntSLGANDK9pUerYWyw@mail.gmail.com
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On 11 December 2013 00:28, Greg Stark <stark(at)mit(dot)edu> wrote:
> On Wed, Dec 11, 2013 at 12:14 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> Block sampling, with parameter to specify sample size. +1
>
> Simon this is very frustrating. Can you define "block sampling"?

Blocks selected using Vitter's algorithm, using a parameterised
fraction of the total.

When we select a block we should read all rows on that block, to help
identify the extent of clustering within the data.

--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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