| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: 9.5: Better memory accounting, towards memory-bounded HashAgg |
| Date: | 2014-08-19 08:25:13 |
| Message-ID: | 1408436713.2335.217.camel@jeff-desktop |
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| Lists: | pgsql-hackers |
On Thu, 2014-08-14 at 12:52 -0400, Robert Haas wrote:
> It appears to me that the performance characteristics for this version
> are not significantly different from version 1. I have not looked at
> the code.
While trying to reproduce your results, I noticed what might be around a
1% regression just from adding the 3 fields to MemoryContextData. If I
cut it down to adding just one field, the regression disappears.
The results are fairly noisy, so I could be chasing the wrong thing. But
one reason to believe it is that I pushed the size of MemoryContextData
above 64, which sounds like it might be an important threshold.
Regards,
Jeff Davis
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