Re: Refactor function pg_get_multixact_stats (src/backend/utils/adt/multixactfuncs.c)

On Tue, Jun 30, 2026 at 09:23:20AM -0300, Ranier Vilela wrote:
> Move the GetMultiXactInfo() call and the resulting computations
> into the branch where the values are actually consumed, narrowing
> the scope of the related local variables to that branch. This
> matches the usual pattern for privileged stats functions, which
> skip the underlying work entirely for callers who can't see the
> result, and avoids touching shared MultiXact state when there is no
> caller around to observe it.

That's indeed wasteful, so applied as it is my business.

> While here, size the memset() that NULLs the output row off
> sizeof(nulls) rather than *sizeof(bool) * tupdesc->natts*.
> The two are equivalent today, since nulls is a fixed 4-element array
> matching the function's declared return type, but relying the
> memset() with *natts* is an unnecessary dependency.
> If a column were ever added to the function's SQL definition without a
> matching update to this array, the old code would silently write
> past the end of nulls.

But I left this one out. It's really impossible to miss.
--
Michael