Improve comments for row filtering and toast interaction in logical replication.

Reported-by: Antonin Houska
Author: Amit Kapila
Reviewed-by: Antonin Houska, Ajin Cherian
Discussion: https://postgr.es/m/84638.1649152255@antos

diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 20d0b1e1253cd6abe223b37888fbe861b36967ba..9d33630464c8598bde4dea5a3ee15256000abf3f 100644 (file)
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -1237,10 +1237,11 @@ pgoutput_row_filter(Relation relation, TupleTableSlot *old_slot,
         * For inserts, we only have the new tuple.
         *
         * For updates, we can have only a new tuple when none of the replica
-        * identity columns changed but we still need to evaluate the row filter
-        * for new tuple as the existing values of those columns might not match
-        * the filter. Also, users can use constant expressions in the row filter,
-        * so we anyway need to evaluate it for the new tuple.
+        * identity columns changed and none of those columns have external data
+        * but we still need to evaluate the row filter for the new tuple as the
+        * existing values of those columns might not match the filter. Also, users
+        * can use constant expressions in the row filter, so we anyway need to
+        * evaluate it for the new tuple.
         *
         * For deletes, we only have the old tuple.
         */