doc: Correct description of restart_lsn in pg_replication_slots

Previously the document explained that restart_lsn indicates the LSN of
oldest WAL won't be automatically removed during checkpoints. But
since v13 this was no longer true thanks to max_slot_wal_keep_size.

Back-patch to v13 where max_slot_wal_keep_size was added.

Author: Fujii Masao
Discussion: https://postgr.es/m/6497f1e9-3148-c5da-7e49-b2fddad9a42f@oss.nttdata.com

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 8945959f9d2a8c104511d7a7928785dbd7f592e7..198ed62e96f1dabdf499047f57be815f2c48d12e 100644 (file)
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -11214,7 +11214,9 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
       
        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.  NULL
+       automatically removed during checkpoints unless this LSN
+       gets behind more than 
+       from the current LSN.  NULL
        if the LSN of this slot has never been reserved.