| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Jim Nasby <decibel(at)decibel(dot)org> |
| Cc: | Magnus Hagander <magnus(at)hagander(dot)net>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: [COMMITTERS] pgsql: Teach tuplesort.c about "top N" sorting, in which only the first |
| Date: | 2007-05-04 18:29:27 |
| Message-ID: | 5382.1178303367@sss.pgh.pa.us |
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Jim Nasby <decibel(at)decibel(dot)org> writes:
> If the method is disk it would be nice to know how much spilled to
> disk. That would tell you if it would be worth increasing work_mem,
> and by how much.
Well, a more radical proposal is to add a whole 'nother line to the
output, which would give us room for several bits of info. Perhaps
like this:
-> Sort (cost=840.19..865.19 rows=10000 width=244) (actual time=151.769..152.157 rows=100 loops=1)
Sort Key: fivethous
Sort Method: top-N Memory: 17KB
-> Seq Scan on tenk1 (cost=0.00..458.00 rows=10000 width=244) (actual
or
Sort Method: disk Memory: 1000KB Disk: 18482KB
Not sure what other info might be useful.
regards, tom lane
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