| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Craig A(dot) James" <cjames(at)modgraph-usa(dot)com> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Poor performance o |
| Date: | 2006-03-22 04:31:43 |
| Message-ID: | 10012.1143001903@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-performance |
"Craig A. James" <cjames(at)modgraph-usa(dot)com> writes:
> Tom Lane wrote:
>> Given the sizes of the tables involved, you'd likely have to boost up
>> work_mem before the planner would consider a hash join. What nondefault
>> configuration settings do you have, anyway?
> shared_buffers = 20000
> work_mem = 32768
> effective_cache_size = 300000
So for a 6M-row table, 32M work_mem would allow ... um ... 5 bytes per
row. It's not happening :-(
Try boosting work_mem by a factor of 100 and seeing whether a hash-based
join actually wins or not. If so, we can discuss where the sane setting
really falls, if not there's no point.
regards, tom lane
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