Horton

Re: Spread checkpoint sync

Greg Smith <greg@2ndquadrant.com>

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From: Greg Smith <greg@2ndquadrant.com>
To: Alvaro Herrera <alvherre@commandprompt.com>
Cc: Rob Wultsch <wultsch@gmail.com>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, Jeff Janes <jeff.janes@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2010-12-07T15:27:28Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add new buffers_backend_fsync field to pg_stat_bgwriter.

Alvaro Herrera wrote:
> Why would multiple bgwriter processes worry you?
>
> Of course, it wouldn't work to have multiple processes trying to execute
> a checkpoint simultaneously, but what if we separated the tasks so that
> one process is in charge of checkpoints, and another one is in charge of
> the LRU scan?
>   

I was commenting more in the context of development resource 
allocation.  Moving toward that design would be helpful, but it alone 
isn't enough to improve the checkpoint sync issues.  My concern is that 
putting work into that area will be a distraction from making progress 
on those.  If individual syncs take so long that the background writer 
gets lost for a while executing them, and therefore doesn't do LRU 
cleanup, you've got a problem that LRU-related improvements probably 
aren't enough to solve.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services and Support        www.2ndQuadrant.us
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