On 07.06.2011 10:21, Simon Riggs wrote:
On Mon, Jun 6, 2011 at 11:25 PM, Robert Haas<robertmh...@gmail.com>  wrote:
It strikes me, though, that we
could probably get nearly all of the benefit of this patch by being
willing to zero the first sizeof(XLogRecord) bytes following a record,
but not the rest of the buffer.  That would pretty much wipe out any
chance of an xl_prev match, I think, and would likely still get nearly
all of the performance benefit.

Which adds something onto the path of every XlogInsert(), rather than
once per page, so I'm a little hesitant to agree.

You would only need to do it just before you write out the WAL. I guess you'd need to grab WALInsertLock in XLogWrite() to prevent more WAL records from being inserted on the page until you're done zeroing it, though.

--
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com

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