doc: Document that subscriptions to same server might hang

diff --git a/doc/src/sgml/ref/create_subscription.sgml b/doc/src/sgml/ref/create_subscription.sgml
index 2c91eb6f50485c87ba0408c3752fb1f0487cb00c..dd5eda043a54a822b31e59ff4f96b0d40ad09a53 100644 (file)
--- a/doc/src/sgml/ref/create_subscription.sgml
+++ b/doc/src/sgml/ref/create_subscription.sgml
@@ -226,6 +226,19 @@ CREATE SUBSCRIPTION subscription_name
    how to configure access control between the subscription and the
    publication instance.
   
+
+  
+   Creating a subscription that connects to the same database cluster (for
+   example, to replicate between databases in the same cluster or to replicate
+   within the same database) will only succeed if the replication slot is not
+   created as part of the same command.  Otherwise, the CREATE
+   SUBSCRIPTION call will hang.  To make this work, create the
+   replication slot separately (using the
+   function pg_create_logical_replication_slot with the
+   plugin name pgoutput) and create the subscription using
+   the parameter create_slot = false.  This is an
+   implementation restriction that might be lifted in a future release.
+