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From: Atul Kumar <akumar14871@gmail.com>
Date: Tue, 8 Apr 2025 18:39:01 +0530
Message-ID: <CA+ONtZ6psqRG5Rdfwbp7wgJ9fyo4VHx1CPmR941HtWxrz4tc2g@mail.gmail.com>
Subject: Re: Wal file query
To: pgsql-general <pgsql-general@lists.postgresql.org>
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I got the error:

Wal control functions cannot be executed during recovery.

I need the solution that should in when streaming replication is
configured.

My postgres version is 13.20


Regards.

On Tue, 8 Apr 2025, 17:32 Kashif Zeeshan, <kashi.zeeshan@gmail.com> wrote:

> Hi Atul
>
> Start by looking at the current WAL LSN and insert LSN. The
> pg_current_wal_lsn is the location of the last write. The
> pg_current_wal_insert_lsn is the logical location and reflects data in
> the buffer that has not been written to disk. There is also a flush value
> that shows what has been written to durable storage.
>
> [postgres] # select pg_current_wal_lsn(), pg_current_wal_insert_lsn();
>  pg_current_wal_lsn | pg_current_wal_insert_lsn
> --------------------+---------------------------
>  76/7D000000        | 76/7D000028
> (1 row)
>
> Although you can guess the name of the WAL file based on the above output=
, it is best to use the pg_walfile_name function.
>
>
> [postgres] # select pg_walfile_name('76/7D000028');
>      pg_walfile_name
> --------------------------
>  00000001000000760000007D
> (1 row)
>
>
> For details visit following link : https://www.crunchydata.com/blog/postg=
res-wal-files-and-sequuence-numbers
>
>
> Thanks
>
> Kashif Zeeshan
>
>
>
> On Tue, Apr 8, 2025 at 4:44=E2=80=AFPM Atul Kumar <akumar14871@gmail.com>=
 wrote:
>
>> In streaming replication What is the way to check which "WAL file" is
>> currently in use in primary  and in standby ?
>>
>>
>> Regards.
>>
>

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<div dir=3D"auto">I got the error:<div dir=3D"auto"><br></div><div dir=3D"a=
uto">Wal control functions cannot be executed during recovery.</div><div di=
r=3D"auto"><br></div><div dir=3D"auto">I need the solution that should in w=
hen streaming replication is configured.=C2=A0</div><div dir=3D"auto"><br><=
/div><div dir=3D"auto">My postgres version is 13.20</div><div dir=3D"auto">=
<br></div><div dir=3D"auto"><br></div><div dir=3D"auto">Regards.=C2=A0</div=
></div><br><div class=3D"gmail_quote gmail_quote_container"><div dir=3D"ltr=
" class=3D"gmail_attr">On Tue, 8 Apr 2025, 17:32 Kashif Zeeshan, &lt;<a hre=
f=3D"mailto:kashi.zeeshan@gmail.com">kashi.zeeshan@gmail.com</a>&gt; wrote:=
<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bord=
er-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr">Hi=C2=A0Atul<div>=
<br></div><div>Start by looking at the current WAL LSN and insert LSN. The =
<code>pg_current_wal_lsn</code> is the location of the last write. The <cod=
e>pg_current_wal_insert_lsn</code>
 is the logical location and reflects data in the buffer that has not=20
been written to disk. There is also a flush value that shows what has=20
been written to durable storage.</div><div><pre><code></code></pre></div><d=
iv><pre><code>[postgres] # select pg_current_wal_lsn(), pg_current_wal_inse=
rt_lsn();
 pg_current_wal_lsn | pg_current_wal_insert_lsn
--------------------+---------------------------
 76/7D000000        | 76/7D000028
(1 row)
</code></pre><pre><code>Although you can guess the name of the WAL file bas=
ed on the above output, it is best to use the <code>pg_walfile_name</code> =
function.</code></pre><pre><code><br></code></pre><pre><code><pre><code>[po=
stgres] # select pg_walfile_name(&#39;76/7D000028&#39;);
     pg_walfile_name
--------------------------
 00000001000000760000007D
(1 row)</code></pre><pre><code><br></code></pre><pre><code>For details visi=
t following link : <a href=3D"https://www.crunchydata.com/blog/postgres-wal=
-files-and-sequuence-numbers" target=3D"_blank" rel=3D"noreferrer">https://=
www.crunchydata.com/blog/postgres-wal-files-and-sequuence-numbers</a></code=
></pre><pre><code><br></code></pre><pre><code>Thanks</code></pre><pre><code=
>Kashif Zeeshan</code></pre></code></pre></div><div><br></div></div><br><di=
v class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Tue, Apr 8=
, 2025 at 4:44=E2=80=AFPM Atul Kumar &lt;<a href=3D"mailto:akumar14871@gmai=
l.com" target=3D"_blank" rel=3D"noreferrer">akumar14871@gmail.com</a>&gt; w=
rote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0p=
x 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir=
=3D"auto">In streaming replication=C2=A0What is the way to check which &quo=
t;WAL file&quot; is currently in use in primary=C2=A0 and in standby ?<div =
dir=3D"auto"><br></div><div dir=3D"auto"><br></div><div dir=3D"auto">Regard=
s.</div></div>
</blockquote></div>
</blockquote></div>

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