Re: 9.5: Better memory accounting, towards memory-bounded HashAgg - Mailing list pgsql-hackers

From Jeff Davis
Subject Re: 9.5: Better memory accounting, towards memory-bounded HashAgg
Date
Msg-id 1408436713.2335.217.camel@jeff-desktop
Whole thread Raw
In response to Re: 9.5: Better memory accounting, towards memory-bounded HashAgg  (Robert Haas <robertmhaas@gmail.com>)
List 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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