| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | "Saul, Jean Paolo" <paolo(dot)saul(at)verizonconnect(dot)com> |
| Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: BUG #15609: synchronous_commit=off insert performance regression with secondary indexes |
| Date: | 2019-01-30 01:36:14 |
| Message-ID: | CAH2-WznxL5vK9vwtXEPS28D5mjUi374665=Jg3p1ObC1MJw1tQ@mail.gmail.com |
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| Lists: | pgsql-bugs |
On Tue, Jan 29, 2019 at 2:05 PM Saul, Jean Paolo
<paolo(dot)saul(at)verizonconnect(dot)com> wrote:
> Before each test run, I drop and recreate the table and indexes.
What happens if you don't create bool_idx, or replace it with another
index on some other column? I notice that you didn't show any case
that doesn't have this index, except for the PK-only case, which is
actually faster. I surmise that that's the common factor in all of the
test cases where you have observed a regression. It would be nice to
confirm or disprove this theory.
The nbtree code is known to deal poorly with low cardinality indexes
[1], something I'm currently working to address. Are you comparing
installations that are on the same hardware and operating system?
[1] https://postgr.es/m/CAH2-Wzmf0fvVhU+SSZpGW4Qe9t--j_DmXdX3it5JcdB8FF2EsA@mail.gmail.com
--
Peter Geoghegan
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