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Date: Tue, 29 Oct 2024 14:02:13 +0300
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Subject: Re: Vacuum statistics
To: Alexander Korotkov <aekorotkov@gmail.com>
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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From: Alena Rybakina <a.rybakina@postgrespro.ru>
In-Reply-To: <CAPpHfdvSo3mfH=2m4ADCHAuN=22SnBY3TrPaPbGKTw3r_Jaw7Q@mail.gmail.com>
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On 28.10.2024 16:40, Alexander Korotkov wrote:
> On Sun, Aug 25, 2024 at 6:59 PM 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 = 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.
>
I haven’t thought about this before and agree with you. Thanks for the 
clarification! I'll fix the patch this evening and release the updated 
version.

-- 
Regards,
Alena Rybakina
Postgres Professional

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    <div class="moz-cite-prefix">On 28.10.2024 16:40, Alexander Korotkov
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAPpHfdvSo3mfH=2m4ADCHAuN=22SnBY3TrPaPbGKTw3r_Jaw7Q@mail.gmail.com">
      <pre class="moz-quote-pre" wrap="">On Sun, Aug 25, 2024 at 6:59 PM Alena Rybakina
<a class="moz-txt-link-rfc2396E" href="mailto:a.rybakina@postgrespro.ru">&lt;a.rybakina@postgrespro.ru&gt;</a> wrote:
</pre>
      <blockquote type="cite">
        <pre class="moz-quote-pre" wrap="">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, &amp;hashiter))
!= NULL)
{
     CHECK_FOR_INTERRUPTS();

     tabentry = (PgStat_StatTabEntry *) entry-&gt;data;

     if (tabentry != NULL &amp;&amp; tabentry-&gt;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?
</pre>
      </blockquote>
      <pre class="moz-quote-pre" wrap="">
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.

</pre>
    </blockquote>
    I haven’t thought about this before and agree with you. Thanks for
    the clarification! I'll fix the patch this evening and release the
    updated version.<br>
    <span style="white-space: pre-wrap">
</span>
    <pre class="moz-signature" cols="72">-- 
Regards,
Alena Rybakina
Postgres Professional</pre>
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