Re: POC: Lock updated tuples in tuple_update() and tuple_delete()

On Tue, Mar 7, 2023 at 4:50 AM Andres Freund <andres@anarazel.de> wrote:
> On 2023-03-02 14:28:56 +0400, Pavel Borisov wrote:
> > 2. Heap updates with low tuple concurrency:
> > Prepare with pkeys (pgbench -d postgres -i -I dtGvp -s 300 --unlogged-tables)
> > Update 3*10^7 rows, 50 conns (pgbench postgres -f
> > ./update-only-account.sql -s 300 -P10 -M prepared -T 600 -j 5 -c 50)
> >
> > Result: Both patches and master are the same within a tolerance of
> > less than 0.7%.
>
> What exactly does that mean? I would definitely not want to accept a 0.7%
> regression of the uncontended case to benefit the contended case here...

I don't know what exactly Pavel meant, but average overall numbers for
low concurrency are.
master: 420401 (stddev of average 233)
patchset v11: 420111 (stddev of average 199)
The difference is less than 0.1% and that is very safely within the error.

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Regards,
Alexander Korotkov