Re: recovery_command has precedence over phisical slots?

On Fri, 2022-08-19 at 16:54 +0200, Giovanni Biscontini wrote:
> Hello everyone, 
> I'm experiencing a behaviour I don't really understand if is a misconfiguration or a wanted behaviour:
> 1) I set up a primary server (a.k.a. db1) with and archive_command to a storage
> 2) I set up a replica (a.k.a. db2) that created a slot named as slot_2 and that has the recovery_command set to read archived wal on the storage.
> If I shutdown replica db2 during a pgbench I see the safe_wal_size queried from pg_replication_slots on the primary decrease to a certain amount but still in the max_slot_wal_kepp_size window: even
> if I restart the replica db2 before the slot_state changes to unreserved or lost I see that the replica gets needed wals from the storage using recovery_command but doesn't use slot on primary.
> Only if I comment the recovery command on the .conf of the replica then it uses slot.
> If this is a wanted behaviour I can't understand the need of slots on primary.

This is normal behavior and is no problem.

After the standby has caught up using "restore_command", it will connection to
the primary as defined in "primary_conninfo" and stream WAL from there.

Yours,
Laurenz Albe
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