|From:||Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>|
|To:||Satoshi Nagayasu <snaga(at)uptime(dot)jp>|
|Cc:||Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>|
|Subject:||Re: New statistics for WAL buffer dirty writes|
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Satoshi Nagayasu escribió:
> With this patch, walwriter process and each backend process
> would sum up dirty writes, and send it to the stat collector.
> So, the value could be saved in the stat file, and could be
> kept on restarting.
> The statistics could be retreive with using
> pg_stat_get_xlog_dirty_writes() function, and could be reset
> with calling pg_stat_reset_shared('walwriter').
> Now, I have one concern.
> The reset time could be captured in globalStats.stat_reset_timestamp,
> but this value is the same with the bgwriter one.
> So, once pg_stat_reset_shared('walwriter') is called,
> stats_reset column in pg_stat_bgwriter does represent
> the reset time for walwriter, not for bgwriter.
> How should we handle this? Should we split this value?
> And should we have new system view for walwriter?
I think the answer to the two last questions is yes. It doesn't seem to
make sense, to me, to have a single reset timings for what are
effectively two separate things.
Please submit an updated patch to next CF. I'm marking this one
returned with feedback. Thanks.
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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