> Bill of Materials Traversal ( ~ 62k records).
>
> ISAM* pg 8.0 pg 8.1 devel delta 8.0->8.1
> running time 63 sec 90 secs 71 secs 21%
> cpu load 17% 45% 32% 29%
> loadsecs** 10.71 40.5 22.72 44%
> recs/sec 984 688 873
> recs/loadsec 5882 1530 2728
>
> *ISAM is an anonymous commercial ISAM library in an optimized server
> architecture (pg smokes the non-optimized flat file version).
> **Loadsecs being seconds of CPU at 100% load.

One thing that might interest you is that the penalty in 8.1 for
stats_command_string=true in this type of access pattern is very high: I
was experimenting to see if the new cpu efficiency gave me enough of a
budget to start using this. This more than doubled the cpu load to
around 70% with a runtime of 82 seconds. This is actually worse than
8.0 .

This *might* be a somewhat win32 specific issue. I've had issues with
the stats collector before. Anyways, the feature is a frill so it's not
a big deal.

Merlin



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"Merlin Moncure" <merlin.moncure@rcsonline.com> writes:
> One thing that might interest you is that the penalty in 8.1 for
> stats_command_string=true in this type of access pattern is very high: I
> was experimenting to see if the new cpu efficiency gave me enough of a
> budget to start using this. This more than doubled the cpu load to
> around 70% with a runtime of 82 seconds. This is actually worse than
> 8.0 .

That seems quite peculiar; AFAICS the pgstat code shouldn't be any
slower than before. At first I thought it might be because we'd
increased PGSTAT_ACTIVITY_SIZE, but actually that happened before
8.0 release, so it shouldn't be a factor in this comparison.

Can anyone else confirm a larger penalty for stats_command_string in
HEAD than in 8.0? A self-contained test case would be nice too.

regards, tom lane

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