From: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
---|---|
To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
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: | 2020-10-22 17:11:58 |
Message-ID: | CANP8+j+7FCoOh1ryJPowhHi0hc6R-xH+m8jRfDHNAGC6brUu7g@mail.gmail.com |
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On Fri, 16 Oct 2020 at 20:12, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> The TPS/throughput is about what you'd expect for the two hour run:
>
> 18,988.762398 TPS for the patch
> 11,123.551707 TPS for the master branch.
Very good.
> Patch:
>
> statement latencies in milliseconds:
> 0.294 UPDATE pgbench_accounts SET abalance = abalance +
> :delta WHERE aid = :aid1;
>
> Master:
>
> statement latencies in milliseconds:
> 0.604 UPDATE pgbench_accounts SET abalance = abalance +
> :delta WHERE aid = :aid1;
The average latency is x2. What is the distribution of latencies?
Occasional very long or all uniformly x2?
I would guess that holding the page locks will also slow down SELECT
workload, so I think you should also report that workload as well.
Hopefully that will be better in the latest version.
I wonder whether we can put this work into a background process rather
than pay the cost in the foreground? Perhaps that might not need us to
hold page locks??
--
Simon Riggs http://www.EnterpriseDB.com/
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