Skip site navigation (1) Skip section navigation (2)

Re: Hash id in pg_stat_statements

From: Peter Geoghegan <peter(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Daniel Farina <daniel(at)heroku(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Hash id in pg_stat_statements
Date: 2012-10-03 18:54:27
Message-ID: CAEYLb_UacLG7ezPwrpm+8F-nmO_MEX8Sjc5YT0v=ppoQ=P4fmA@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On 3 October 2012 19:04, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Daniel Farina <daniel(at)heroku(dot)com> writes:
>> Instead, I think it makes sense to assign a number -- arbitrarily, but
>> uniquely -- to the generation of a new row in pg_stat_statements, and,
>> on the flip side, whenever a row is retired its number should be
>> eliminated, practically, for-ever.  This way re-introductions between
>> two samplings of pg_stat_statements cannot be confused for a
>> contiguously maintained statistic on a query.
>
> This argument seems sensible to me.  Is there any use-case where the
> proposed counter wouldn't do what people wished to do with an exposed
> hash value?

Yes. The hash could be used to aggregate query execution costs across
entire WAL-based replication clusters. I'm not opposed to Daniel's
suggestion, though.

-- 
Peter Geoghegan       http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training and Services


In response to

Responses

pgsql-hackers by date

Next:From: Alexander KorotkovDate: 2012-10-03 19:41:05
Subject: Re: gistchoose vs. bloat
Previous:From: Tom LaneDate: 2012-10-03 18:04:04
Subject: Re: Hash id in pg_stat_statements

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group