The description for pg_replication_slots.restart_lsn

Hi,

The document explains that restart_lsn column in pg_replication_slots view is:

The address (LSN) of oldest WAL which still might be required by
the consumer of this slot and thus won't be automatically removed
during checkpoints.

But the latter part is not true in v13 thanks to max_slot_wal_keep_size.
I think that we need to update it as follows. Thought?

The address (LSN) of oldest WAL which still might be required by
the consumer of this slot and thus won't be automatically removed
during checkpoints unless this LSN gets behind more than
max_slot_wal_keep_size from the current LSN.

Patch attached.

Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION