doc: Clarify some things on pg_receivexlog reference page

diff --git a/doc/src/sgml/ref/pg_receivexlog.sgml b/doc/src/sgml/ref/pg_receivexlog.sgml
index 0dcba4d54fb7f1ce44609938343af996435a1f13..5ac1f4d9ecb9b8b120f1b3cd860642b67fb48b00 100644 (file)
--- a/doc/src/sgml/ref/pg_receivexlog.sgml
+++ b/doc/src/sgml/ref/pg_receivexlog.sgml
@@ -31,7 +31,7 @@ PostgreSQL documentation
    Description
   
   
-   pg_receivexlog is used to stream transaction log
+   pg_receivexlog is used to stream the transaction log
    from a running PostgreSQL cluster. The transaction
    log is streamed using the streaming replication protocol, and is written
    to a local directory of files. This directory can be used as the archive
@@ -49,19 +49,19 @@ PostgreSQL documentation
   
 
   
-   Unlike the standby's WAL receiver, pg_receivexlog
+   Unlike the WAL receiver of a PostgreSQL standby server, pg_receivexlog
    by default flushes WAL data only when a WAL file is closed.
-   --synchronous option must be specified to flush WAL data
-   in real time and ensure it's safely flushed to disk.
+   The option --synchronous must be specified to flush WAL data
+   in real time.
   
 
   
    The transaction log is streamed over a regular
-   PostgreSQL connection, and uses the replication
+   PostgreSQL connection and uses the replication
    protocol. The connection must be made with a superuser or a user
    having REPLICATION permissions (see
    ), and pg_hba.conf
-   must explicitly permit the replication connection. The server must also be
+   must permit the replication connection. The server must also be
    configured with  set high enough to
    leave at least one session available for the stream.
   
@@ -137,10 +137,18 @@ PostgreSQL documentation
          When this option is used, pg_receivexlog will report
          a flush position to the server, indicating when each segment has been
          synchronized to disk so that the server can remove that segment if it
-         is not otherwise needed. --synchronous option must
-         be specified when making pg_receivexlog run as
-         synchronous standby by using replication slot. Otherwise WAL data
-         cannot be flushed frequently enough for this to work correctly.
+         is not otherwise needed.
+        
+
+        
+         When the replication client
+         of pg_receivexlog is configured on the
+         server as a synchronous standby, then using a replication slot will
+         report the flush position to the server, but only when a WAL file is
+         closed.  Therefore, that configuration will cause transactions on the
+         primary to wait for a long time and effectively not work
+         satisfactorily.  The option --synchronous (see
+         below) must be specified in addition to make this work correctly.
         
       
      
@@ -153,6 +161,13 @@ PostgreSQL documentation
         send a status packet back to the server immediately after flushing,
         regardless of --status-interval.
        
+
+       
+        This option should be specified if the replication client
+        of pg_receivexlog is configured on the
+        server as a synchronous standby, to ensure that timely feedback is
+        sent to the server.
+