Re: Add a permission check to pg_stat_get_backend_subxact()

On 08/09/2026 02:33, shihao zhong wrote:
> pg_stat_get_backend_subxact() does not check the caller's permissions.
> Every other function in the "Per-Backend Statistics Functions" table
> that reports what a session is doing calls HAS_PGSTAT_PERMISSIONS()
> first and returns NULL to a caller who may not see it.  This one is the
> only exception.

pg_stat_get_backend_wal, pg_stat_get_backend_io, and
pg_stat_get_backend_lock also lack this check. Out of scope here, but
perhaps worth a followup patch?

> - adds the HAS_PGSTAT_PERMISSIONS() check, with a regression test that
>   fails without it;

I believe the tests should also cover a non-superuser with explicit
pg_read_all_stats permission (see 0002 attached)

> - documents the rule above that table.  The table says nothing about
>   permissions today; the rule is only written down for the dynamic
>   statistics views;
>
> - corrects one column name in the docs: subxact_overflow should be
>   subxact_overflowed.

The C tuple descriptor still says "subxact_overflow" -- most likely the
source of the confusion.

TupleDescInitEntry(tupdesc, (AttrNumber) 2, "subxact_overflow",
BOOLOID, -1, 0);

Best, Jim