Horton

Re: Add sub-transaction overflow status in pg_stat_activity

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, "David G. Johnston" <david.g.johnston@gmail.com>, Amit Singh <amitksingh.mumbai@gmail.com>, Julien Rouhaud <rjuju123@gmail.com>, "Bossart, Nathan" <bossartn@amazon.com>, Dilip Kumar <dilipbalaut@gmail.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-11-14T21:03:25Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Nov 14, 2022 at 12:47 PM Andres Freund <andres@anarazel.de> wrote:
>> I'd go the other way. It's pretty unimportant whether it overflowed, it's
>> important how many subtxns there are. The cases where overflowing causes real
>> problems are when there's many thousand subtxns - which one can't judge just
>> from suboverflowed alone. Nor can monitoring a boolean tell you whether you're
>> creeping closer to the danger zone.

> This is the opposite of what I believe to be true. I thought the
> problem is that once a single backend overflows the subxid array, all
> snapshots have to be created suboverflowed, and this makes visibility
> checking more expensive.

Yeah, that's what I thought too.  Andres, please enlarge ...

			regards, tom lane

Commits

  1. Fix comment that was missing a word.

  2. Expose some information about backend subxact status.