| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Deleting older versions in unique indexes to avoid page splits |
| Date: | 2020-10-24 15:01:06 |
| Message-ID: | CAH2-Wznn3YYrup5NhKRFtj31thUEDpf-An9gB3ZsT6mFJ1YFzw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sat, Oct 24, 2020 at 2:55 AM Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> The problem I highlighted is that the average UPDATE latency is x2
> what it is on current HEAD. That is not consistent with the reported
> TPS, so it remains an issue and that isn't obvious.
Why do you say that? I reported that the UPDATE latency is less than
half for the benchmark.
There probably are some workloads with worse latency and throughput,
but generally only with high contention/small indexes. I'll try to
fine tune those, but some amount of it is probably inevitable. On
average query latency is quite a lot lower with the patch (where it is
affected at all - the mechanism is only used with non-hot updates).
--
Peter Geoghegan
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