Re: pgbench progress report improvements - split 3 v2 - A

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Noah Misch <noah(at)leadboat(dot)com>, PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>, Pavel Stěhule <pavel(dot)stehule(at)gmail(dot)com>
Subject: Re: pgbench progress report improvements - split 3 v2 - A
Date: 2013-10-08 12:15:03
Message-ID: alpine.DEB.2.02.1310081408500.28568@sto
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers


> On Sat, Oct 5, 2013 at 6:10 PM, Noah Misch <noah(at)leadboat(dot)com> wrote:
>> The sum of the squares of the latencies wraps after 2^63/(10^12 * avg_latency
>> * nclients) seconds. That's unlikely to come up with the ordinary pgbench
>> script, but one can reach it in a few hours when benchmarking a command that
>> runs for many seconds. If we care, we can track the figure as a double. I
>> merely added a comment about it.
>
> Using a double seems wise to me.

I think that both int64 & double are fine.

The likelyhood of having underflows (double) or overflows/wraparounds
(int64) seems pretty low for any practical run. I took the former because
it is exact... up to when it is totally wrong. The later one may provide
underestimated results silently: it would fail more continuously.

So I'm okay if it is changed to double consistently.

--
Fabien.

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Andrew Dunstan 2013-10-08 12:33:13 Re: Patch: FORCE_NULL option for copy COPY in CSV mode
Previous Message Atri Sharma 2013-10-08 11:52:44 Re: Re: custom hash-based COUNT(DISTINCT) aggregate - unexpectedly high memory consumption