I will write a technical document about Sigres in a week.
Hideyuki
Bruce Momjian wrote:
I am still unclear why sigres is better than a temporary file system. I
relize your patch is faster, but what is about your patch that makes it
faster.
And if we were going to add such capability, we would name it based on
what it does, rather than on a 'sigres' mode.
---------------------------------------------------------------------------
Hideyuki Kawashima wrote:
Simon,
Not checkpointing at all is not a good plan, since this will lead to an
enormous build up of WAL files and a very long recovery time if the
system does fail.
I appreciate your detailed comments.
Following your comments, I revised the problem.
Sigres-0.1.3 does checkpointings.
In summary, the features of Sigres-0.1.3 are as follows.
0: 10% faster than conventional PostgreSQL under tmpfs.
1: Checkpointings are continually executed.
2: Sigres mode is in default (the mode can be turned off via postgresql.conf).
3: issue_xlog_sync is called only by bgwriter (continually, via
createcheckpoint)
4: The entity of XLogWrite (_XLogWrite in my code) is called by both
backends and a bgwriter.
For each backend, _XLogWrite is called only via AdvanceXLInsertBuffer.
For a bgwriter, _XLogWrite is called via CreateCheckPoint.
Please try it if you have interest.
http://sourceforge.jp/projects/sigres/
Again, I really appreciate beneficial comments from this community !
Regards,
-- Hideyuki
--
Hideyuki Kawashima (Ph.D.)
University of Tsukuba
Assistant Professor
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Hideyuki Kawashima (Ph.D), University of Tsukuba,
Graduate School of Systems and Information Engineering
Assistant Professor, TEL: +81-29-853-5322
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