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Data Bases > Pgsql Patches > Re: Sorting wri...
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Re: Sorting writes during checkpoint

by tgl@[EMAIL PROTECTED] (Tom Lane) May 4, 2008 at 07:35 PM

Greg Smith <gsmith@[EMAIL PROTECTED]
> writes:
> On Sun, 4 May 2008, Tom Lane wrote:
>> However, I am completely unable to measure any performance improvement
>> from it.  Given the possible risk of out-of-memory failures, I think
the
>> patch should not be applied without some direct proof of performance
>> benefits, and I don't see any.

> Fair enough.  There were some pgbench results attached to the original 
> patch submission that gave me a good idea how to replicate the situation

> where there's some improvement.

Well, I tried a pgbench test similar to that one --- on smaller hardware
than was re****ted, so it was a bit smaller test case, but it should have
given similar results.  I didn't see any improvement; if anything it was
a bit worse.  So that's what got me concerned.

Of course it's notoriously hard to get consistent numbers out of pgbench
anyway, so I'd rather see some other test case ...

> I expect I can take a shot at quantifying 
> that independantly near the end of this month if nobody else gets to it 
> before then (I'm stuck sorting out a number of OS level issue right now 
> before my testing system is online again).  Was planning to take a
longer 
> look at Greg Stark's prefetching work at that point as well.

Fair enough.  Unless someone can volunteer to test sooner, I think we
should drop this item from the current commitfest queue.

			regards, tom lane

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 2 Posts in Topic:
Re: Sorting writes during checkpoint
gsmith@[EMAIL PROTECTED]   2008-05-04 19:12:32 
Re: Sorting writes during checkpoint
tgl@[EMAIL PROTECTED] (T  2008-05-04 19:35:46 

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tan12V112 Sat Sep 6 15:36:24 CDT 2008.