Re: pgbench progress report improvements - split 2

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Noah Misch <noah(at)leadboat(dot)com>
Cc: PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>, pavel(dot)stehule(at)gmail(dot)com
Subject: Re: pgbench progress report improvements - split 2
Date: 2013-09-24 18:42:15
Message-ID: alpine.DEB.2.02.1309242032330.8198@sto
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers


Hello Noah,

> meet all those goals simultaneously with simpler code, can we not?
>
> int64 wait = (int64) (throttle_delay *
> Min(7.0, -log(1 - pg_erand48(thread->random_state))));

If you truncate roughly the multipler, as it is done here with "min", you
necessarily create a bias, my random guess would be a 0.5% under
estimation, but maybe it is more... Thus you would have to compute and the
correcting factor as well. Its computation is a little bit less easy than
with the quantized formula where I just used a simple SUM, and you have to
really do the maths here. So I would keep the simple solution, but it is
fine with me if you do the maths!

--
Fabien.

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Stephen Frost 2013-09-24 19:22:49 Re: record identical operator
Previous Message Andres Freund 2013-09-24 18:25:53 Re: FW: REVIEW: Allow formatting in log_line_prefix