Re: XLogFlush invoked about twice as much after 9.2 group commit enhancement - Mailing list pgsql-hackers

From Jeff Janes
Subject Re: XLogFlush invoked about twice as much after 9.2 group commit enhancement
Date
Msg-id CAMkU=1y0+GYtkXqr5VbqwCxqBaNt99tfRYXOazTsBis418iVNQ@mail.gmail.com
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In response to Re: XLogFlush invoked about twice as much after 9.2 group commit enhancement  (Peter Geoghegan <pg@heroku.com>)
List pgsql-hackers
On Tue, May 7, 2013 at 9:23 PM, Peter Geoghegan <pg@heroku.com> wrote:
On Tue, May 7, 2013 at 12:48 PM, Jeff Janes <jeff.janes@gmail.com> wrote:
> Anyway, I don't see this behavior change when turning on wal_debug and
> looking in the logfiles for 'xlog flush request' messages.

That could have everything to do with the hardware you're using. In
general, the higher the cost of an fsync, the more useful it is to
amortize that cost among concurrently committing transactions.

True, but that is going to happen with a proportional increase in throughput, which he reported not seeing.  At least originally.  I'm not sure what to think now.

Cheers,

Jeff

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