Re: Add pg_stat_kind_info system view

On Tue, Jun 30, 2026 at 05:36:57PM -0500, Sami Imseih wrote:
> +        <structfield>count</structfield> <type>bigint</type>
> +       </para>
> +       <para>
> +        Number of tracked entries for this kind. For fixed-amount
> kinds, this is
> +        always 1. For variable-numbered kinds, this is the number of objects
> +        currently tracked. <literal>NULL</literal> if the kind does not track
> +        entry counts.
> +       </para>
> +      </entry>
> 
> I think this should be 0 for all kinds by default. Only ever > 0 for
> variable-numbered
> kinds with entry tracking enabled. No NULLs. The fields should be called
> "entry_count" instead of "count". We should update the documentation to
> reflect that as well. That seems easier to query than having mixed NULLs and
> numbers.

IMO, in this case, NULL should be a synonym of "I don't know", which
is what entry_count set to false means.  0 means "I know, there is no
data".  I'd be OK with dropping the part about fixed-sized stats where
we enforce 1, and use NULL instead, though.
--
Michael