| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Jaime Casanova <jcasanov(at)systemguards(dot)com(dot)ec>, decibel <decibel(at)decibel(dot)org>, psql performance list <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: [PERFORMANCE] work_mem vs temp files issue |
| Date: | 2010-01-13 15:42:38 |
| Message-ID: | 10990.1263397358@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> I had an idea at one point of making explain show the planned and
> actual # of batches for each hash join. I believe that "actual # of
> batches > 1" is isomorphic to "hash join went to disk". The code is
> actually pretty easy; the hard part is figuring out what to do about
> the UI. The choices seem to be:
> 1. Create a new EXPLAIN option just for this - what would we call it?
> 2. Think of some more, similar things and come up with a new EXPLAIN
> option covering all of them - what else would go along with?
> 3. Sandwhich it into an existing EXPLAIN option, most likely VERBOSE.
> 4. Display it by default.
Treat it the same as the Sort-node actual usage information. We did not
add a special option when we added that.
regards, tom lane
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