Re: Vacuum statistics

On Sun, Aug 25, 2024 at 6:59 PM Alena Rybakina
<a(dot)rybakina(at)postgrespro(dot)ru> wrote:
> I didn't understand correctly - did you mean that we don't need SRF if
> we need to display statistics for a specific object?
>
> Otherwise, we need this when we display information on all database
> objects (tables or indexes):
>
> while ((entry = ScanStatSnapshot(pgStatLocal.snapshot.stats, &hashiter))
> != NULL)
> {
> CHECK_FOR_INTERRUPTS();
>
> tabentry = (PgStat_StatTabEntry *) entry->data;
>
> if (tabentry != NULL && tabentry->vacuum_ext.type == type)
> tuplestore_put_for_relation(relid, rsinfo, tabentry);
> }
>
> I know we can construct a HeapTuple object containing a TupleDesc,
> values, and nulls for a particular object, but I'm not sure we can
> augment it while looping through multiple objects.
>
> /* Initialise attributes information in the tuple descriptor */
>
> tupdesc = CreateTemplateTupleDesc(PG_STAT_GET_SUBSCRIPTION_STATS_COLS);
>
> ...
>
> PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
>
>
> If I missed something or misunderstood, can you explain in more detail?

Actually, I mean why do we need a possibility to return statistics for
all tables/indexes in one function call? User anyway is supposed to
use pg_stat_vacuum_indexes/pg_stat_vacuum_tables view, which do
function calls one per relation. I suppose we can get rid of
possibility to get all the objects in one function call and just
return a tuple from the functions like other pgstatfuncs.c functions
do.

------
Regards,
Alexander Korotkov
Supabase