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: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, "michael@paquier.xyz" <michael@paquier.xyz>, "andres@anarazel.de" <andres@anarazel.de>, "sulamul@gmail.com" <sulamul@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2021-11-01T16:57:27Z
Lists: pgsql-hackers 
"Bossart, Nathan" <bossartn@amazon.com> writes:
> On 10/31/21, 1:55 PM, "Tom Lane" <tgl@sss.pgh.pa.us> wrote:
>> 1. Attached is a proposed patch to get rid of the calls in trgm_regexp.c.

> Should there be a list_free(trgmNFA->queue) at the end of
> transformGraph()?

There could be, but that's visibly invoked only once per 
createTrgmNFAInternal call, so I didn't think it was worthwhile
to do so (unlike the case for processState).  If we were concerned
about leakage in that function, the hash table would be a far
bigger issue.

			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.