Horton

Re: Replication slot stats misgivings

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>, Andres Freund <andres@anarazel.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Date: 2021-04-22T05:09:15Z
Lists: pgsql-hackers 
On Thu, Apr 22, 2021 at 1:50 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Thu, Apr 22, 2021 at 8:26 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> >
>
> Few comments:
> 1.
> I think we want stats collector to not use pgStatLocalContext unless
> it has read the stats file similar to other cases. So probably, we
> should allocate it in pgStatLocalContext when we read 'R' message in
> pgstat_read_statsfiles. Also, the function pgstat_get_replslot_entry
> should not use pgStatLocalContext to allocate the hash table.

Agreed.

> 2.
> + if (replSlotStatHash != NULL)
> + (void) hash_search(replSlotStatHash,
> +    (void *) &(msg->m_slotname),
> +    HASH_REMOVE,
> +    NULL);
>
> Why have you changed this part from using NameStr?

I thought that since the hash table is created with the key size
sizeof(NameData) it's better to use NameData for searching as well.

> 3.
> +# Check that replicatoin slot stats are expected.
>
> Typo. replicatoin/replication

Will fix in the next version.

Regards,

-- 
Masahiko Sawada
EDB:  https://www.enterprisedb.com/

Commits

  1. Doc: Update logical decoding stats information.

  2. Fix tests for replication slots stats.

  3. Update replication statistics after every stream/spill.

  4. Fix the computation of slot stats for 'total_bytes'.

  5. Another try to fix the test case added by commit f5fc2f5b23.

  6. Use HTAB for replication slot statistics.

  7. Fix test case added by commit f5fc2f5b23.

  8. Add information of total data processed to replication slot stats.

  9. Use NameData datatype for slotname in stats.