| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | pgsql-hackers(at)lists(dot)postgresql(dot)org,Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>,Takayuki Tsunakawa <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> |
| Subject: | Re: Statement-level rollback |
| Date: | 2018-12-07 20:03:45 |
| Message-ID: | FB78E0B3-54E1-4E2A-880E-C5348A63FC1C@anarazel.de |
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| Lists: | pgsql-hackers |
On December 7, 2018 11:56:55 AM PST, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote:
>BTW, a couple of months ago I measured the performance implications for
>a single update under pgbench and it represented a decrease of about
>3%-5%. Side-effects such as xid consumption have worse implications,
>but as far as performance is concerned, it's not as bad as all that.
I don't think that's a fair test for the performance downsides. For pgbench with modifications the full commit is such a large portion of the time that you'd need to make things a lot slower to show a large slowdown. And for ro pgbench the subxacts don't matter that much. It'd probably be more meaningful to have a mixed workload of 15 ro statements per xact in one type of session, and 5rw /10ro in another.
Andres
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