Re: Latch for the WAL writer - further reducing idle wake-ups.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Peter Geoghegan <peter(at)2ndquadrant(dot)com>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Latch for the WAL writer - further reducing idle wake-ups.
Date: 2012-05-03 03:42:40
Message-ID: 11231.1336016560@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> ... It seems unlikely to cause any real
> problem if WAL writer takes a couple seconds to get with the program
> after a long period of inactivity; note that an async commit will kick
> it anyway, and a sync commit will probably half to flush WAL whether
> the WAL writer wakes up or not.

That's a good point. What about only kicking the WAL writer in code
paths where a backend found itself having to write/flush WAL for itself?
The added overhead is very surely negligible in such a situation.

regards, tom lane

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