Thread: Help on recovering my standby
On Wed, Jun 22, 2016 at 12:22 PM, Alan Hodgson <ahodgson@lists.simkin.ca> wrote:
On Tuesday 21 June 2016 19:34:18 Ramalingam, Sankarakumar wrote:
> Hi I have my standby (streaming replication) down due to missing wal files.
> You would see the same error in the logs stating "cannot find the wal file
> ..." What is the best way to get it going so that when we switch between
> standby and primary once in a while they are in sync?
>
> Currently I am working on a CERT server and hence there is no outage
> concerns. I need to repeat the same process on prod once I get it going
> successfully. Any help is appreciated.
>
You should keep your WAL files from the master for at least as long as the
slave might be offline (plus startup time), somewhere the slave can copy them
from when needed (shared file system, object store, scp target, whatever).
See the postgresql.conf parameter archive_command and the corresponding
recovery.conf parameter restore_command.
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It would be really helpful if you included PostgreSQL version and O/S in your problem description, but since you have not, I will give a "generic" fix.
It is doubtful, but you can check the pg_xlog on the master for the "missing" WAL files and if they are there, simply rsync them to the standby.
If you are truly missing WAL files in your slave/standy, then you need to rebuild the slave as per standard procedures.
If you are truly missing WAL files in your slave/standy, then you need to rebuild the slave as per standard procedures.
Make sure you change wal_keep_segments value on the master to be sufficiently highly so that the problem does not occur again.
Once you make the change, be sure to reload the config file on the master
Either
SELECT pg_reload_conf();
SELECT pg_reload_conf();
or
pg_ctl reload -D your_data_dir
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Melvin Davidson
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wish to share my fantasy is entirely up to you.