On Tue, Jun 7, 2011 at 8:27 AM, Heikki Linnakangas
<heikki.linnakangas@enterprisedb.com> wrote:
> On 07.06.2011 10:21, Simon Riggs wrote:
>>
>> On Mon, Jun 6, 2011 at 11:25 PM, Robert Haas<robertmhaas@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.
How would that help?
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
