Re: pg_get_multixact_members not documented

On Mon, Jun 30, 2025 at 06:19:10PM +0300, Sami Imseih wrote:
> Perhaps we should think about removing this description, what do you think?

I think it's a good topic for another patch/thread. Chances are it's not
the only description that could be updated.

>> Looking again, pg_get_multixact_members() might need to be added to this
>> list of exceptions:
>>
>> However, the functions shown in Table 9.84, except age and mxid_age,
>> use a 64-bit type xid8 that does not wrap around during the life of an
>> installation and can be converted to xid by casting if required; see
>> Section 67.1 for details.
>
> This function returns an xid and not an int8 such as for example
> ```
> { oid => '3819', descr => 'view members of a multixactid',
> proname => 'pg_get_multixact_members', prorows => '1000', proretset => 't',
> provolatile => 'v', prorettype => 'record', proargtypes => 'xid',
> proallargtypes => '{xid,xid,text}', proargmodes => '{i,o,o}',
> proargnames => '{multixid,xid,mode}', prosrc => 'pg_get_multixact_members' },
> ```
> ```
> { oid => '2943', descr => 'get current transaction ID',
> proname => 'txid_current', provolatile => 's', proparallel => 'u',
> prorettype => 'int8', proargtypes => '', prosrc => 'pg_current_xact_id' },
> ```
> am I missing something?

That's what I mean. I think it should say

However, the functions shown in Table 9.84, except age, mxid_age, and
pg_get_multixact_members, use a 64-bit type xid8 that...

I noticed that this list of exceptions doesn't exist on v13-v15, presumably
because the docs for age() and mxid_age() were only back-patched to v16
(see commits 48b5aa3 and 15afb7d), which is strange because I believe those
functions are much older. I don't see any discussion about this choice,
either. We should probably back-patch those commits to v13 as a
prerequisite to applying this patch.

--
nathan