Horton

Re: [PATCH] Support Int64 GUCs

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Aleksander Alekseev <aleksander@timescale.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Li Japin <japinli@hotmail.com>, Nathan Bossart <nathandbossart@gmail.com>
Date: 2024-09-26T16:39:10Z
Lists: pgsql-hackers 
Alexander Korotkov <aekorotkov@gmail.com> writes:
> Do you think we don't need int64 GUCs just now, when 64-bit
> transaction ids are far from committable shape?  Or do you think we
> don't need int64 GUCs even if we have 64-bit transaction ids?  If yes,
> what do you think we should use for *_age variables with 64-bit
> transaction ids?

I seriously doubt that _age values exceeding INT32_MAX would be
useful, even in the still-extremely-doubtful situation that we
get to true 64-bit XIDs.  But if you think we must have that,
we could still use float8 GUCs for them.  float8 is exact up
to 2^53 (given IEEE math), and you certainly aren't going to
convince me that anyone needs _age values exceeding that.
For that matter, an imprecise representation of such an age
limit would still be all right wouldn't it?

			regards, tom lane