*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
***************
*** 14098,14103 **** postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
--- 14098,14106 ----
     <indexterm>
      <primary>pg_last_xact_replay_timestamp</primary>
     </indexterm>
+    <indexterm>
+     <primary>pg_primary_conninfo</primary>
+    </indexterm>
  
     <para>
      The functions shown in <xref
***************
*** 14168,14173 **** postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
--- 14171,14187 ----
          the function returns NULL.
         </entry>
        </row>
+       <row>
+        <entry>
+         <literal><function>pg_primary_conninfo()</function></literal>
+        </entry>
+        <entry><type>text</type></entry>
+        <entry>Gets the connection string used to connect to the primary
+         when using streaming replication. When the server has been started
+         normally without recovery, or when file based recovery is in
+         progress, the function returns NULL.
+        </entry>
+       </row>
       </tbody>
      </tgroup>
     </table>
*** a/src/backend/access/transam/xlog.c
--- b/src/backend/access/transam/xlog.c
***************
*** 8829,8834 **** pg_last_xlog_replay_location(PG_FUNCTION_ARGS)
--- 8829,8857 ----
  }
  
  /*
+  * Report the connection info that the walreceiver is using to talk to the
+  * primary.
+  */
+ Datum
+ pg_primary_conninfo(PG_FUNCTION_ARGS)
+ {
+ 	/* use volatile pointer to prevent code rearrangement */
+ 	volatile WalRcvData *walrcv = WalRcv;
+ 	XLogRecPtr	recptr;
+ 	char		conninfo[MAXCONNINFO];
+ 
+ 	SpinLockAcquire(&walrcv->mutex);
+ 	recptr = walrcv->receivedUpto;
+ 	memcpy(conninfo, walrcv->conninfo, MAXCONNINFO);
+ 	SpinLockRelease(&walrcv->mutex);
+ 
+ 	if (recptr.xlogid == 0 && recptr.xrecoff == 0 && conninfo[0] != '\0')
+ 		PG_RETURN_NULL();
+ 
+ 	PG_RETURN_TEXT_P(cstring_to_text(conninfo));
+ }
+ 
+ /*
   * Compute an xlog file name and decimal byte offset given a WAL location,
   * such as is returned by pg_stop_backup() or pg_xlog_switch().
   *
*** a/src/include/catalog/pg_proc.h
--- b/src/include/catalog/pg_proc.h
***************
*** 3386,3392 **** DESCR("xlog filename, given an xlog location");
  
  DATA(insert OID = 3810 (  pg_is_in_recovery		PGNSP PGUID 12 1 0 0 f f f t f v 0 0 16 "" _null_ _null_ _null_ _null_ pg_is_in_recovery _null_ _null_ _null_ ));
  DESCR("true if server is in recovery");
! 
  DATA(insert OID = 3820 ( pg_last_xlog_receive_location	PGNSP PGUID 12 1 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_last_xlog_receive_location _null_ _null_ _null_ ));
  DESCR("current xlog flush location");
  DATA(insert OID = 3821 ( pg_last_xlog_replay_location	PGNSP PGUID 12 1 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_last_xlog_replay_location _null_ _null_ _null_ ));
--- 3386,3393 ----
  
  DATA(insert OID = 3810 (  pg_is_in_recovery		PGNSP PGUID 12 1 0 0 f f f t f v 0 0 16 "" _null_ _null_ _null_ _null_ pg_is_in_recovery _null_ _null_ _null_ ));
  DESCR("true if server is in recovery");
! DATA(insert OID = 3819 ( pg_primary_conninfo PGNSP PGUID 12 1 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_primary_conninfo _null_ _null_ _null_ ));
! DESCR("connection string for primary");
  DATA(insert OID = 3820 ( pg_last_xlog_receive_location	PGNSP PGUID 12 1 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_last_xlog_receive_location _null_ _null_ _null_ ));
  DESCR("current xlog flush location");
  DATA(insert OID = 3821 ( pg_last_xlog_replay_location	PGNSP PGUID 12 1 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_last_xlog_replay_location _null_ _null_ _null_ ));