Re: Parent/child context relation in pg_get_backend_memory_contexts()

On Wed, Apr 03, 2024 at 04:20:39PM +0300, Melih Mutlu wrote:
> Michael Paquier <michael(at)paquier(dot)xyz>, 14 Şub 2024 Çar, 10:23 tarihinde
> şunu yazdı:
>> I was reading the patch, and using int[] as a representation of the
>> path of context IDs up to the top-most parent looks a bit strange to
>> me, with the relationship between each parent -> child being
>> preserved, visibly, based on the order of the elements in this array
>> made of temporary IDs compiled on-the-fly during the function
>> execution. Am I the only one finding that a bit strange? Could it be
>> better to use a different data type for this path and perhaps switch
>> to the names of the contexts involved?
>
> Do you find having the path column strange all together? Or only using
> temporary IDs to generate that column? The reason why I avoid using context
> names is because there can be multiple contexts with the same name. This
> makes it difficult to figure out which context, among those with that
> particular name, is actually included in the path. I couldn't find any
> other information that is unique to each context.

I've been re-reading the patch again to remember what this is about,
and I'm OK with having this "path" column in the catalog. However,
I'm somewhat confused by the choice of having a temporary number that
shows up in the catalog representation, because this may not be
constant across multiple calls so this still requires a follow-up
temporary ID <-> name mapping in any SQL querying this catalog. A
second thing is that array does not show the hierarchy of the path;
the patch relies on the order of the elements in the output array
instead.
--
Michael