Re: Use COPY for populating all pgbench tables

I guess that COPY will still be slower than  generating the data
server-side ( --init-steps=...G... ) ?

What I'd really like to see is providing all the pgbench functions
also on the server. Specifically the various random(...) functions -
random_exponential(...), random_gaussian(...), random_zipfian(...) so
that also custom data generationm could be easily done server-side
with matching distributions.

On Thu, Jun 8, 2023 at 7:34 AM David Rowley <dgrowleyml@gmail.com> wrote:
>
> On Thu, 8 Jun 2023 at 07:16, Tristan Partin <tristan@neon.tech> wrote:
> >
> > master:
> >
> > 50000000 of 50000000 tuples (100%) done (elapsed 260.93 s, remaining 0.00 s))
> > vacuuming...
> > creating primary keys...
> > done in 1414.26 s (drop tables 0.20 s, create tables 0.82 s, client-side generate 1280.43 s, vacuum 2.55 s, primary keys 130.25 s).
> >
> > patchset:
> >
> > 50000000 of 50000000 tuples (100%) of pgbench_accounts done (elapsed 243.82 s, remaining 0.00 s))
> > vacuuming...
> > creating primary keys...
> > done in 375.66 s (drop tables 0.14 s, create tables 0.73 s, client-side generate 246.27 s, vacuum 2.77 s, primary keys 125.75 s).
>
> I've also previously found pgbench -i to be slow.  It was a while ago,
> and IIRC, it was due to the printfPQExpBuffer() being a bottleneck
> inside pgbench.
>
> On seeing your email, it makes me wonder if PG16's hex integer
> literals might help here.  These should be much faster to generate in
> pgbench and also parse on the postgres side.
>
> I wrote a quick and dirty patch to try that and I'm not really getting
> the same performance increases as I'd have expected. I also tested
> with your patch too and it does not look that impressive either when
> running pgbench on the same machine as postgres.
>
> pgbench copy speedup
>
> ** master
> drowley@amd3990x:~$ pgbench -i -s 1000 postgres
> 100000000 of 100000000 tuples (100%) done (elapsed 74.15 s, remaining 0.00 s)
> vacuuming...
> creating primary keys...
> done in 95.71 s (drop tables 0.00 s, create tables 0.01 s, client-side
> generate 74.45 s, vacuum 0.12 s, primary keys 21.13 s).
>
> ** David's Patched
> drowley@amd3990x:~$ pgbench -i -s 1000 postgres
> 100000000 of 100000000 tuples (100%) done (elapsed 69.64 s, remaining 0.00 s)
> vacuuming...
> creating primary keys...
> done in 90.22 s (drop tables 0.00 s, create tables 0.01 s, client-side
> generate 69.91 s, vacuum 0.12 s, primary keys 20.18 s).
>
> ** Tristan's patch
> drowley@amd3990x:~$ pgbench -i -s 1000 postgres
> 100000000 of 100000000 tuples (100%) of pgbench_accounts done (elapsed
> 77.44 s, remaining 0.00 s)
> vacuuming...
> creating primary keys...
> done in 98.64 s (drop tables 0.00 s, create tables 0.01 s, client-side
> generate 77.47 s, vacuum 0.12 s, primary keys 21.04 s).
>
> I'm interested to see what numbers you get.  You'd need to test on
> PG16 however. I left the old code in place to generate the decimal
> numbers for versions < 16.
>
> David