Re: BUG #15609: synchronous_commit=off insert performance regression with secondary indexes

From: "Saul, Jean Paolo" <paolo(dot)saul(at)verizonconnect(dot)com>
To: Peter Geoghegan <pg(at)bowt(dot)ie>
Cc: Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org>
Subject: Re: BUG #15609: synchronous_commit=off insert performance regression with secondary indexes
Date: 2019-02-12 02:59:35
Message-ID: CA+73ANecUjXUHg49GAJH-iiK9zuyatF=y-g2DjkOELy9heVBzg@mail.gmail.com
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Thanks.

I am only able to get over 100K if I change the insert query from:
INSERT INTO test_indexes (int_data )
VALUES ( (RANDOM()*10000)::BIGINT % 2 ); -- note the modulus
38057.023869 tps for PG9.5
28257.312372 tps for PG11

to:
INSERT INTO test_indexes (int_data )
VALUES ( (RANDOM()*10000)::BIGINT );
83065.111054 tps for PG9.5
130080.356992 tps for PG11

So I am assuming at this point you are not able to replicate this behavior?
It might be a setting we have on our end, I just don't know what it its yet.

On Tue, 12 Feb 2019 at 15:06, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:

> On Mon, Feb 11, 2019 at 6:01 PM Saul, Jean Paolo
> <paolo(dot)saul(at)verizonconnect(dot)com> wrote:
> > Thanks for the tip Peter. Unfortunately it did not move the needle. Just
> curious what numbers are you getting when you are testing?
>
> Well over 100k tps, usually ~150k tps, quite consistently (I need to
> use -M prepared to get over 100k tps, though). I can see the progress
> by using pgbench's -P option (e.g. -P 5 to see progress reports every
> 5 seconds), which is how I've determined that it's consistent. I am
> using the master branch, but I can't think of any reason why it would
> be different to v11.
>
> I do have a fairly high end though still workstation grade SSD -- a
> Samsung 970 PRO 512GB. I imagine that your server is at least as
> powerful as my workstation by every measure, so this shouldn't matter.
>
> --
> Peter Geoghegan
>

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