Re: Ignore hash indices on replicas
От | Jeff Janes |
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Тема | Re: Ignore hash indices on replicas |
Дата | |
Msg-id | CAMkU=1xL_dM8ONK1390iR_aOtQMkG1GrGGppEQRuytmw4Us7cA@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: Ignore hash indices on replicas (Steven Schlansker <steven@likeness.com>) |
Список | pgsql-general |
On Mon, Aug 20, 2012 at 10:29 AM, Steven Schlansker <steven@likeness.com> wrote: > > On Aug 19, 2012, at 2:37 PM, Jeff Davis <pgsql@j-davis.com> wrote: > >> On Tue, 2012-07-10 at 00:09 -0700, Steven Schlansker wrote: >>> show that our particular application is faster by quite a bit when a >>> hash index is available. >> >> Can you publish the results somewhere? It might provoke some interest. > > I might be able to spend some time looking at making this public, but the general parameters are: > > 122M rows, lookup key is a UUID type. Lookups are ~1000 random keys at a time (as in, a giant SELECT * FROM table WHEREkey IN (?,?,?,?,…) How well cached is the data? If it has to be read from disk, then a bitmap index scan on a btree index with effective_io_concurrency set high might do quite well, assuming you can convince the planner to use one. Cheers, Jeff
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