Re: PoC: Partial sort
| От | Marti Raudsepp |
|---|---|
| Тема | Re: PoC: Partial sort |
| Дата | |
| Msg-id | CABRT9RDd-P2RLRdHsMq8rCOB46k4a5O+bGz_up2bRGeeH4R6oQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: PoC: Partial sort (Alexander Korotkov <aekorotkov@gmail.com>) |
| Список | pgsql-hackers |
On Tue, Jan 14, 2014 at 9:28 PM, Alexander Korotkov <aekorotkov@gmail.com> wrote:
The real data is from the "release" table from MusicBrainz database dump: https://musicbrainz.org/doc/MusicBrainz_Database/Download . It's nontrivial to set up though, so if you still need the real data, I can upload a pgdump for you.
On Tue, Jan 14, 2014 at 11:16 PM, Marti Raudsepp <marti@juffo.org> wrote:Oh, this actually highlights a performance regression with the partial sort patch.Interesting. Could you share the dataset?
It occurs with many datasets if work_mem is sufficiently low (10MB in my case). Here's a quicker way to reproduce a similar issue:
create table foo as select i, i as j from generate_series(1,10000000) i;
create index on foo(i);
explain analyze select * from foo a join foo b using (i, j);
create table foo as select i, i as j from generate_series(1,10000000) i;
create index on foo(i);
explain analyze select * from foo a join foo b using (i, j);
The real data is from the "release" table from MusicBrainz database dump: https://musicbrainz.org/doc/MusicBrainz_Database/Download . It's nontrivial to set up though, so if you still need the real data, I can upload a pgdump for you.
Regards,
Marti
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