RE: WAL File Recovery on Standby Server Stops Before End of WAL Files

Hi Kyotaro and Dilip,

Thank you for getting back to me.

Kyotaro: I ran pg_dump and the output was "pg_waldump: fatal: could not read file "00000001000004190000005A": read 50
of8192".  I'm guessing that it means that wal file 00000001000004190000005A is corrupted and that is why the recovery
processstops there.  Is there any way to fix the file?
 

Dilip:   setting the log level to debug2 did not provide any additional information.  Here are the log entries:

2021-10-28 06:51:06.166 MDT [7556] LOG:  restored log file "000000010000041900000059" from archive
2021-10-28 06:51:06.464 MDT [7556] DEBUG:  got WAL segment from archive
2021-10-28 06:51:06.579 MDT [7556] LOG:  restored log file "00000001000004190000005A" from archive
2021-10-28 06:51:06.854 MDT [7556] DEBUG:  got WAL segment from archive
2021-10-28 06:51:07.107 MDT [7556] LOG:  consistent recovery state reached at 419/5ABFFFF8
2021-10-28 06:51:07.107 MDT [7556] DEBUG:  switched WAL source from archive to stream after failure
2021-10-28 06:51:07.109 MDT [7844] LOG:  database system is ready to accept read only connections
2021-10-28 06:51:07.152 MDT [7844] DEBUG:  forked new backend, pid=6900 socket=6068

I set the log level to debug5 and here is what I got:

2021-10-28 06:25:41.262 MDT [6288] CONTEXT:  WAL redo at 419/5ABFFF60 for Btree/INSERT_LEAF: off 130
2021-10-28 06:25:41.262 MDT [6288] DEBUG:  record known xact 33776257 latestObservedXid 33776257
2021-10-28 06:25:41.262 MDT [6288] CONTEXT:  WAL redo at 419/5ABFFFA0 for Heap/INSERT: off 95 flags 0x00
2021-10-28 06:25:41.262 MDT [6288] LOG:  consistent recovery state reached at 419/5ABFFFF8
2021-10-28 06:25:41.263 MDT [6288] DEBUG:  switched WAL source from archive to stream after failure
2021-10-28 06:25:41.264 MDT [5512] LOG:  database system is ready to accept read only connections

Does the "switched WAL source from archive to stream after failure" indicate a problem with the WAL file?

Anyway, it looks like I need to restore the standby server from a new backup.  Thank you both for your help.

Sincerely,
-Les

-----Original Message-----
From: Dilip Kumar <dilipbalaut@gmail.com>
Sent: October 27, 2021 10:29 PM
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: Ryan, Les <Les.Ryan@wsp.com>; pgsql-generallists.postgresql.org <pgsql-general@lists.postgresql.org>
Subject: Re: WAL File Recovery on Standby Server Stops Before End of WAL Files

On Thu, Oct 28, 2021 at 7:28 AM Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote:
>
> At Wed, 27 Oct 2021 16:42:52 +0000, "Ryan, Les" <Les.Ryan@wsp.com>
> wrote in
> > 2021-10-27 10:26:31.467 MDT [2012] LOG:  redo starts at 419/5229A858
> ...
> > 2021-10-27 10:26:36.188 MDT [2012] LOG:  restored log file
> > "00000001000004190000005A" from archive
> > 2021-10-27 10:26:36.750 MDT [2012] LOG:  consistent recovery state
> > reached at 419/5ABFFFF8
> > 2021-10-27 10:26:36.752 MDT [6204] LOG:  database system is ready to
> > accept read only connections
> > 2021-10-27 10:26:36.823 MDT [6040] LOG:  started streaming WAL from
> > primary at 419/5A000000 on timeline 1
> >
> >   *   There are many more WAL files available starting with 00000001000004190000005B but the restore process always
stopsat 00000001000004190000005A.
 
> >
> > I have two questions:
> >
> >   *   Why does the WAL file recovery process now stop after it reads 00000001000004190000005A?
> >   *   What do I need to do to get PostgreSQL to recover the rest of the available WAL files.
>
> The info above alone donesn't clearly suggest anything about the
> reason. Could you show the result of "pg_waldump
> 00000001000004190000005A 2>&1 | tail -5"?  What I'm expecting to see
> is an error message from pg_waldump before the end of the file. It
> would be the immediate cause of the problem.

+1, that will be the best place to start with, additionally, you can
enable DEBUG2 message so that from logs we can identify why it could not continue recovery from the archive.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

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