Horton

Re: Spread checkpoint sync

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, Itagaki Takahiro <itagaki.takahiro@gmail.com>, Greg Smith <greg@2ndquadrant.com>, Ron Mayer <rm_pg@cheapcomplexdevices.com>, Josh Berkus <josh@agliodbs.com>, pgsql-hackers@postgresql.org
Date: 2011-01-31T20:27:25Z
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.

Robert Haas wrote:
> Back to the idea at hand - I proposed something a bit along these
> lines upthread, but my idea was to proactively perform the fsyncs on
> the relations that had gone the longest without a write, rather than
> the ones with the most dirty data.  I'm not sure which is better.
> Obviously, doing the ones that have "gone idle" gives the OS more time
> to write out the data, but OTOH it might not succeed in purging much
> dirty data.  Doing the ones with the most dirty data will definitely
> reduce the size of the final checkpoint, but might also cause a
> latency spike if it's triggered immediately after heavy write activity
> on that file.

Crazy idea #2 --- it would be interesting if you issued an fsync
_before_ you wrote out data to a file that needed an fsync.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

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