Horton

Re: Vacuum: allow usage of more than 1GB of work mem

Simon Riggs <simon@2ndquadrant.com>

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From: Simon Riggs <simon@2ndquadrant.com>
To: Claudio Freire <klaussfreire@gmail.com>
Cc: Simon Riggs <simon@2ndquadrant.com>, PostgreSQL-Dev <pgsql-hackers@postgresql.org>
Date: 2016-09-06T06:45:45Z
Lists: pgsql-hackers 
On 5 September 2016 at 21:58, Claudio Freire <klaussfreire@gmail.com> wrote:

>>>> How long does that part ever take? Is there any substantial gain from this?

> Btw, without a further patch to prefetch pages on the backward scan
> for truncate, however, my patience ran out before it finished
> truncating. I haven't submitted that patch because there was an
> identical patch in an older thread that was discussed and more or less
> rejected since it slightly penalized SSDs.

OK, thats enough context. Sorry for being forgetful on that point.

Please post that new patch also.


This whole idea of backwards scanning to confirm truncation seems
wrong. What we want is an O(1) solution. Thinking.

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

Commits

  1. Prefetch blocks during lazy vacuum's truncation scan

  2. Explain unaccounted for space in pgstattuple.