Re: Group Commits Vs WAL Writes

On Thu, Jun 27, 2013 at 3:56 AM, Atri Sharma <atri.jiit@gmail.com> wrote:
> When we do a commit, WAL buffers are written to the disk. This has a
> disk latency for the required I/O.

Check.

> Now, with group commits, do we see a spike in that disk write latency,
> especially in the cases where the user has set wal_buffers to a high
> value?

Well, it does take longer to fsync a larger byte range to disk than a
smaller byte range, in some cases.  But it's generally more efficient
to write one larger range than many smaller ranges, so you come out
ahead on the whole.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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