| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> |
| Cc: | Joel Reymont <joelr1(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: optimizing a cpu-heavy query |
| Date: | 2011-05-19 13:17:28 |
| Message-ID: | 19204.1305811048@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com> writes:
> 2011/4/27 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> Joel Reymont <joelr1(at)gmail(dot)com> writes:
>>> That's a 30x speedup, from 12 minutes down to 38s. Thanks Tom!
>> Huh, I would've bet on a lot more actually. The nodeFunctionscan and
>> nodeAgg code must not be as inefficient as it looks on the surface ...
> Did you mean in that case you can optimize it by collapsing those
> nodes into one?
No, just that the overhead of that code looks like it ought to be much
more than the cost of a few multiplications ...
regards, tom lane
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