diff --git a/contrib/postgres_fdw/option.c b/contrib/postgres_fdw/option.c
index fc3ce6a53a..af38e956e7 100644
--- a/contrib/postgres_fdw/option.c
+++ b/contrib/postgres_fdw/option.c
@@ -489,6 +489,12 @@ process_pgfdw_appname(const char *appname)
 			case 'a':
 				appendStringInfoString(&buf, application_name);
 				break;
+			case 'c':
+				appendStringInfo(&buf, "%lx.%x", (long) (MyStartTime), MyProcPid);
+				break;
+			case 'C':
+				appendStringInfoString(&buf, cluster_name);
+				break;
 			case 'd':
 				appendStringInfoString(&buf, MyProcPort->database_name);
 				break;
diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index 2bb31f1125..17cd90ab12 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -983,6 +983,20 @@ postgres=# SELECT postgres_fdw_disconnect_all();
          <entry><literal>%a</literal></entry>
          <entry>Application name on local server</entry>
         </row>
+        <row>
+         <entry><literal>%c</literal></entry>
+         <entry>
+          Session ID on local server
+          (see <xref linkend="guc-log-line-prefix"/> for details)
+         </entry>
+        </row>
+        <row>
+         <entry><literal>%C</literal></entry>
+         <entry>
+          Cluster name in local server
+          (see <xref linkend="guc-cluster-name"/> for details)
+         </entry>
+        </row>
         <row>
          <entry><literal>%u</literal></entry>
          <entry>User name on local server</entry>
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 6bb81707b0..f1bfe79feb 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -271,7 +271,7 @@ extern int	temp_file_limit;
 
 extern int	num_temp_buffers;
 
-extern char *cluster_name;
+extern PGDLLIMPORT char *cluster_name;
 extern PGDLLIMPORT char *ConfigFileName;
 extern char *HbaFileName;
 extern char *IdentFileName;