Re: Locking B-tree leafs immediately in exclusive mode

On Mon, Jul 9, 2018 at 8:18 PM Peter Geoghegan <pg@bowt.ie> wrote:
> On Mon, Jul 9, 2018 at 9:43 AM, Alexander Korotkov
> <a.korotkov@postgrespro.ru> wrote:
> > In this case it also looks like we observed 1% regression.  Despite 1%
> > may seem to be very small, I think we should clarify whether it really
> > exists.  I have at least two hypothesis about this.
> >
> > 1) There is no real regression, observed difference of TPS is less
> > than error of measurements.  In order to check that we need to retry
> > the experiment multiple times.  Also, if you run benchmark on master
> > before patched version (or vice versa) you should also try to swap the
> > order to make sure there is no influence of the order of benchmarks.
> > 2) If we consider relation between TPS and number of clients, TPS is
> > typically growing with increasing number of clients until reach some
> > saturation value.  After the saturation value, there is some
> > degradation of TPS.  If patch makes some latency lower, that my cause
> > saturation to happen earlier.  In order to check that, we need run
> > benchmarks with various number of clients and draw a graph: TPS
> > depending on clients.
> >
> > So, may I ask you to make more experiments in order to clarify the
> > observed regression?
>
> It would be nice to actually see script_duplicated.sql. I don't know
> exactly what the test case was.

BTW, contents of script_duplicated.sql was posted by Imai, Yoshikazu
in the message body:

> # script_duplicated.sql
> INSERT INTO unordered VALUES (1, 'abcdefghijklmnoprsqtuvwxyz');

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company