Horton

Re: Lots of memory allocated when reassigning Large Objects

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

View thread View on postgr.es
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Guillaume Lelarge <guillaume@lelarge.info>
Cc: Justin Pryzby <pryzby@telsasoft.com>, PostgreSQL Developers <pgsql-hackers@postgresql.org>
Date: 2021-11-29T21:27:49Z
Lists: pgsql-hackers 
Guillaume Lelarge <guillaume@lelarge.info> writes:
> Le lun. 29 nov. 2021 à 20:39, Tom Lane <tgl@sss.pgh.pa.us> a écrit :
>> [ looks closer ... ]  Ah, that patch is a bit buggy: it fails to do the
>> right thing in the cases where the loop does a "continue".  The attached
>> revision seems to behave properly.

> I've tried your patch with my test case. It still uses a lot of memory.
> Actually even more.

Hmm ... I tried it with your test case, and I see the backend completing
the query without going beyond 190MB used (which is mostly shared memory).
Without the patch it blows past that point very quickly indeed.

I'm checking it in HEAD though; perhaps there's something else wrong
in the back branches?

			regards, tom lane

Commits

  1. Avoid leaking memory during large-scale REASSIGN OWNED BY operations.

  2. Reduce memory consumption for pending invalidation messages.