From c7dc56bd6b36b4d6b3c6cc1bb4735f7777272ca3 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Fri, 14 Apr 2023 13:08:02 +0900 Subject: doc: Fix some grammar for logical decoding description and functions This documentation is has been added for the support of logical decoding on standbys. Some markups were missing, hence add some where required. Author: Thom Brown Reviewed-by: Justin Pryzby, Daniel Gustafsson Discussion: https://postgr.es/m/CAA-aLv7xCZ0nBJa-NWe0rxBB28TjFjS2JtjiZMoQ+0wsugG+hQ@mail.gmail.com --- doc/src/sgml/func.sgml | 4 ++-- doc/src/sgml/logicaldecoding.sgml | 22 ++++++++++++---------- doc/src/sgml/monitoring.sgml | 2 +- 3 files changed, 15 insertions(+), 13 deletions(-) (limited to 'doc') diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index e6a7514100..5a47ce4343 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -27084,8 +27084,8 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset Take a snapshot of running transactions and write it to WAL, without - having to wait bgwriter or checkpointer to log one. This is useful for - logical decoding on standby, as logical slot creation has to wait + having to wait for bgwriter or checkpointer to log one. This is useful + for logical decoding on standby, as logical slot creation has to wait until such a record is replayed on the standby. diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml index e61059d71e..cbd3aa804f 100644 --- a/doc/src/sgml/logicaldecoding.sgml +++ b/doc/src/sgml/logicaldecoding.sgml @@ -321,16 +321,18 @@ postgres=# select * from pg_logical_slot_get_changes('regression_slot', NULL, NU VACUUM from removing required rows from the system catalogs, hot_standby_feedback should be set on the standby. In spite of that, if any required rows get removed, the slot gets - invalidated. It's highly recommended to use a physical slot between the primary - and the standby. Otherwise, hot_standby_feedback will work, but only while the - connection is alive (for example a node restart would break it). Then, the - primary may delete system catalog rows that could be needed by the logical - decoding on the standby (as it does not know about the catalog_xmin on the - standby). Existing logical slots on standby also get invalidated if wal_level - on primary is reduced to less than 'logical'. This is done as soon as the - standby detects such a change in the WAL stream. It means, that for walsenders - that are lagging (if any), some WAL records up to the wal_level parameter change - on the primary won't be decoded. + invalidated. It's highly recommended to use a physical slot between the + primary and the standby. Otherwise, hot_standby_feedback + will work but only while the connection is alive (for example a node + restart would break it). Then, the primary may delete system catalog rows + that could be needed by the logical decoding on the standby (as it does + not know about the catalog_xmin on the standby). Existing logical slots + on standby also get invalidated if wal_level on the + primary is reduced to less than logical. + This is done as soon as the standby detects such a change in the WAL stream. + It means that, for walsenders which are lagging (if any), some WAL records up + to the wal_level parameter change on the primary won't be + decoded. diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 0281201745..2903b67170 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -4757,7 +4757,7 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i Number of uses of logical slots in this database that have been - canceled due to old snapshots or a too low + canceled due to old snapshots or too low a on the primary -- cgit v1.2.1