Horton

Re: inefficient loop in StandbyReleaseLockList()

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Bossart, Nathan" <bossartn@amazon.com>
Cc: Andres Freund <andres@anarazel.de>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, "sulamul@gmail.com" <sulamul@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2021-10-28T23:24:08Z
Lists: pgsql-hackers 
"Bossart, Nathan" <bossartn@amazon.com> writes:
> On 10/28/21, 3:25 PM, "Tom Lane" <tgl@sss.pgh.pa.us> wrote:
>> Does it matter what order we're releasing the locks in?

> I'm not seeing anything that indicates the ordering matters.  AFAICT
> either approach would work in this case.  IMO changing the order is
> scarier than switching to foreach(), though.

Yeah, that was my feeling...

			regards, tom lane

Commits

  1. Doc: add some notes about performance of the List functions.

  2. Avoid O(N^2) behavior in SyncPostCheckpoint().

  3. Avoid some other O(N^2) hazards in list manipulation.

  4. Avoid O(N^2) behavior when the standby process releases many locks.