RE: Newly created replication slot may be invalidated by checkpoint

Dear Amit,

> We need to check whether a similar change is required in
> reserve_wal_for_local_slot() as well for sync slots.

Good point. I confirmed similar issue could happen while synchronizing slots.
PSA the reproducer.

0001-PG17... patch simulates the issue that WAL segments were discarded in-between
slot's restart_lsn is set and the pointed record is being protected. Can be
applied atop PG17.
0001-HEAD... patch simulates the issue that restart_lsn obtained from primary is
discarded on standby. This can be applied atop HEAD.

Best regards,
Hayato Kuroda
FUJITSU LIMITED