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In-Reply-To: <c4e4e305-7119-4183-b49a-d7092f4efba3@postgrespro.ru>
From: Alexander Korotkov <aekorotkov@gmail.com>
Date: Mon, 28 Oct 2024 15:40:04 +0200
Message-ID: <CAPpHfdvSo3mfH=2m4ADCHAuN=22SnBY3TrPaPbGKTw3r_Jaw7Q@mail.gmail.com>
Subject: Re: Vacuum statistics
To: Alena Rybakina <a.rybakina@postgrespro.ru>
Cc: Ilia Evdokimov <ilya.evdokimov@tantorlabs.com>, Andrei Zubkov <zubkov@moonset.ru>, 
	Alena Rybakina <lena.ribackina@yandex.ru>, pgsql-hackers <pgsql-hackers@postgresql.org>, 
	a.lepikhov@postgrespro.ru, jian he <jian.universality@gmail.com>
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On Sun, Aug 25, 2024 at 6:59=E2=80=AFPM Alena Rybakina
<a.rybakina@postgrespro.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 =3D ScanStatSnapshot(pgStatLocal.snapshot.stats, &hashiter)=
)
> !=3D NULL)
> {
>      CHECK_FOR_INTERRUPTS();
>
>      tabentry =3D (PgStat_StatTabEntry *) entry->data;
>
>      if (tabentry !=3D NULL && tabentry->vacuum_ext.type =3D=3D 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 =3D 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