Horton

Re: suppressing useless wakeups in logical/worker.c

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Thomas Munro <thomas.munro@gmail.com>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2023-01-26T21:09:51Z
Lists: pgsql-hackers

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Nathan Bossart <nathandbossart@gmail.com> writes:
> On Thu, Jan 26, 2023 at 03:04:30PM -0500, Tom Lane wrote:
>> Hmm.  I'm disinclined to add an assumption that the epoch is in the past,
>> but I take your point that the subtraction would overflow with
>> TIMESTAMP_INFINITY and a negative finite timestamp.  Maybe we should
>> make use of pg_sub_s64_overflow()?

> That would be my vote.  I think the 'diff <= 0' check might need to be
> replaced with something like 'start_time > stop_time' so that we return 0
> for the underflow case.

Right, so more like this.

			regards, tom lane

Commits

  1. Improve TimestampDifferenceMilliseconds to cope with overflow sanely.

  2. Code review for commit 05a7be935.