Re: Replication with Patroni not working after killing secondary and starting again

[Zb B <zbig.poland@xxxxxxxxx>]

> When the secondary starts up it should continue replicating from where
> it stopped. However, it can only do this if the necessary information is
> still available. If WAL files have been deleted in the mean time. it
> can't replay them. There should be error messages in your logs on what
> went wrong

I did another test using different wal_sender_timeout parameter, as the time of the secondary being shut down was longer than the default 60s for this parameter.

I was hoping it would help but the result was the same (records were not replicated to the secondary after the patroni start). Well, I just verified again that the records were replicated after about 15 minutes to the secondary, so probably the timeout setting helped, or I was not patient enough before. Is it normal to wait so long for the replication? (the original transaction in primary took about 5 minutes and was about 3000 small records). I am providing more details for completeness below:

I get the following errors on the primary DB:

2022-04-28 04:36:50.544 EDT [13794] WARNING:  archive_mode enabled, yet archive_command is not set
2022-04-28 04:37:34.893 EDT [14755] ERROR:  replication slot "xyzd3riardb05" does not exist
2022-04-28 04:37:34.893 EDT [14755] STATEMENT:  START_REPLICATION SLOT "xyzd3riardb05" 0/7000000 TIMELINE 18
2022-04-28 04:37:34.915 EDT [14756] ERROR:  replication slot "xyzd3riardb05" does not exist
2022-04-28 04:37:34.915 EDT [14756] STATEMENT:  START_REPLICATION SLOT "xyzd3riardb05" 0/7000000 TIMELINE 18
2022-04-28 04:37:39.925 EDT [14763] ERROR:  replication slot "xyzd3riardb05" does not exist
2022-04-28 04:37:39.925 EDT [14763] STATEMENT:  START_REPLICATION SLOT "xyzd3riardb05" 0/7000000 TIMELINE 18
2022-04-28 04:37:44.924 EDT [14768] ERROR:  replication slot "xyzd3riardb05" does not exist
2022-04-28 04:37:44.924 EDT [14768] STATEMENT:  START_REPLICATION SLOT "xyzd3riardb05" 0/7000000 TIMELINE 18

and after some time such errors stop to appear.

and when I execute:

su postgres -c "psql -c \"SELECT * FROM pg_replication_slots;\""

I get the following the slot seems to exist:

 slot_name   | plugin | slot_type | datoid | database | temporary | active | active_pid | xmin | catalog_xmin | restart_lsn | confirmed_f
lush_lsn | wal_status | safe_wal_size | two_phase
---------------+--------+-----------+--------+----------+-----------+--------+------------+------+--------------+-------------+------------
---------+------------+---------------+-----------
 xyzd3riardb05 |        | physical  |        |          | f         | f      |            |      |              | 0/73289E8   |
         | reserved   |               | f
 pdc2b         |        | physical  |        |          | f         | f      |            |      |              | 0/726D398   |
         | reserved   |               | f
 pdc2b_standby |        | physical  |        |          | f         | f      |            |      |              | 0/726D398   |
         | reserved   |               | f
(3 rows)

And as I said I just verified that the records were replicated after about 15 minutes to the secondary.