Re: Deleting older versions in unique indexes to avoid page splits

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От Peter Geoghegan
Тема Re: Deleting older versions in unique indexes to avoid page splits
Дата
Msg-id CAH2-Wznn3YYrup5NhKRFtj31thUEDpf-An9gB3ZsT6mFJ1YFzw@mail.gmail.com
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Ответ на Re: Deleting older versions in unique indexes to avoid page splits  (Simon Riggs <simon@2ndquadrant.com>)
Ответы Re: Deleting older versions in unique indexes to avoid page splits  (Peter Geoghegan <pg@bowt.ie>)
Список pgsql-hackers
On Sat, Oct 24, 2020 at 2:55 AM Simon Riggs <simon@2ndquadrant.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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