Subject: Re: Minimal logical decoding on standbys
To: Andres Freund <andres@anarazel.de>
Cc: Amit Khandekar <amitdkhan.pg@gmail.com>,
 Robert Haas <robertmhaas@gmail.com>,
 Petr Jelinek <petr.jelinek@2ndquadrant.com>,
 Craig Ringer <craig@2ndquadrant.com>, Petr Jelinek <petr@2ndquadrant.com>,
 pgsql-hackers <pgsql-hackers@postgresql.org>
References: 
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 <CAJ3gD9csOr0LoYoMK9NnfBk0RZmvHXcJAFWFd2EuL=NOfz7PVA@mail.gmail.com>
 <CAJ3gD9eoPH4j-hMbq+_F9c5P=26tokkZGjB1eK4gjr1rcG7a4Q@mail.gmail.com>
 <20190619190138.rufzsld5xgcgshmh@alap3.anarazel.de>
 <CAJ3gD9f_HjQ6qP=+1jwzwy77fwcbT4-M3UvVsqpAzsY-jqM8nw@mail.gmail.com>
 <CA+Tgmoa6GxDQJ4G7zjyXOD4HEzPM7CWwsTcKPdRDnZ9NV4D13Q@mail.gmail.com>
 <CAJ3gD9end8xLBvZ07nbK2SVNOoeMRSye6+6r6=bp2wVvoa9ijw@mail.gmail.com>
 <20190710031424.dfhzlqj2tpvznibe@alap3.anarazel.de>
 <CAJ3gD9d4oN6ik+0ORrgVTOoO=Z3jsEGsfLLZTwtvUK1ZpF7YWQ@mail.gmail.com>
 <5a80cbcb-185c-fb81-02f2-7f26a8ea8efc@enterprisedb.com>
 <20190716172644.nbvjhqoxgpryzlv7@alap3.anarazel.de>
From: tushar <tushar.ahuja@enterprisedb.com>
Message-ID: <f02fe977-22bc-bdd4-5828-140f51fcc583@enterprisedb.com>
Date: Wed, 17 Jul 2019 16:54:55 +0530
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On 07/16/2019 10:56 PM, Andres Freund wrote:
> Even after calling pg_logical_slot_get_changes() multiple times? What
> does
> SELECT * FROM pg_replication_slots; before and after multiple calls return?
>
> Does manually forcing a checkpoint with CHECKPOINT; first on the primary
> and then the standby "fix" the issue?
>
Yes,eventually it gets clean up -after firing multiple times get_changes 
function or checkpoint or even both.
This same behavior we are able to see  on MASTER  -with or without patch.

but is this an old (existing) issue ?
>> b)pg_wal files are not recycling  and every time it is creating new files
>> after firing get_changes function
> I'm not sure what you mean by this. Are you saying that
> pg_logical_slot_get_changes() causes WAL to be written?

No, when i said - created new WAL files , i meant -after each pg_bench 
run NOT after executing  get_changes.

-- 
regards,tushar
EnterpriseDB  https://www.enterprisedb.com/
The Enterprise PostgreSQL Company


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    <div class="moz-cite-prefix">On 07/16/2019 10:56 PM, Andres Freund
      wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:20190716172644.nbvjhqoxgpryzlv7@alap3.anarazel.de">
      <pre wrap="">Even after calling pg_logical_slot_get_changes() multiple times? What
does
SELECT * FROM pg_replication_slots; before and after multiple calls return?

Does manually forcing a checkpoint with CHECKPOINT; first on the primary
and then the standby "fix" the issue?

</pre>
    </blockquote>
    Yes,eventually it gets clean up -after firing multiple times
    get_changes function or checkpoint or even both. <br>
    This same behavior we are able to see  on MASTER  -with or without
    patch.<br>
    <br>
    but is this an old (existing) issue ?<br>
    <blockquote type="cite"
      cite="mid:20190716172644.nbvjhqoxgpryzlv7@alap3.anarazel.de">
      <pre wrap="">
</pre>
      <blockquote type="cite" style="color: #000000;">
        <pre wrap="">b)pg_wal files are not recycling  and every time it is creating new files
after firing get_changes function
</pre>
      </blockquote>
      <pre wrap="">I'm not sure what you mean by this. Are you saying that
pg_logical_slot_get_changes() causes WAL to be written?
</pre>
    </blockquote>
    <p>No, when i said - created new WAL files , i meant -after each
      pg_bench run NOT after executing  get_changes. <br>
    </p>
    <pre class="moz-signature" cols="72">-- 
regards,tushar
EnterpriseDB  <a class="moz-txt-link-freetext" href="https://www.enterprisedb.com/">https://www.enterprisedb.com/</a>
The Enterprise PostgreSQL Company
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