diff -ru postgresql/doc/src/sgml/func.sgml postgresql-is_in_exclusive_backup-patch//doc/src/sgml/func.sgml
--- postgresql/doc/src/sgml/func.sgml	2012-01-26 23:01:31.956613398 +0100
+++ postgresql-is_in_exclusive_backup-patch//doc/src/sgml/func.sgml	2012-03-01 10:58:20.556472776 +0100
@@ -14371,6 +14371,9 @@
     <primary>pg_current_xlog_location</primary>
    </indexterm>
    <indexterm>
+    <primary>pg_is_in_exclusive_backup</primary>
+   </indexterm>
+   <indexterm>
     <primary>pg_start_backup</primary>
    </indexterm>
    <indexterm>
@@ -14424,6 +14427,14 @@
       </row>
       <row>
        <entry>
+        <literal><function>pg_is_in_exclusive_backup()</function></literal>
+        </entry>
+       <entry><type>bool</type></entry>
+       <entry>True if an on-line exclusive backup is still in progress.
+       </entry>
+      </row>
+      <row>
+       <entry>
         <literal><function>pg_start_backup(<parameter>label</> <type>text</> <optional>, <parameter>fast</> <type>boolean</> </optional>)</function></literal>
         </entry>
        <entry><type>text</type></entry>
diff -ru postgresql/src/backend/access/transam/xlogfuncs.c postgresql-is_in_exclusive_backup-patch//src/backend/access/transam/xlogfuncs.c
--- postgresql/src/backend/access/transam/xlogfuncs.c	2012-01-26 23:01:32.032613398 +0100
+++ postgresql-is_in_exclusive_backup-patch//src/backend/access/transam/xlogfuncs.c	2012-03-01 10:48:48.056473056 +0100
@@ -465,3 +465,12 @@
 {
 	PG_RETURN_BOOL(RecoveryInProgress());
 }
+
+/*
+ * Returns bool with current on-line backup mode, a global state.
+ */
+Datum
+pg_is_in_exclusive_backup(PG_FUNCTION_ARGS)
+{
+	PG_RETURN_BOOL(BackupInProgress());
+}
diff -ru postgresql/src/include/access/xlog_internal.h postgresql-is_in_exclusive_backup-patch//src/include/access/xlog_internal.h
--- postgresql/src/include/access/xlog_internal.h	2012-01-26 23:01:32.332613398 +0100
+++ postgresql-is_in_exclusive_backup-patch//src/include/access/xlog_internal.h	2012-03-01 10:48:48.076473056 +0100
@@ -281,5 +281,6 @@
 extern Datum pg_xlog_replay_pause(PG_FUNCTION_ARGS);
 extern Datum pg_xlog_replay_resume(PG_FUNCTION_ARGS);
 extern Datum pg_is_xlog_replay_paused(PG_FUNCTION_ARGS);
+extern Datum pg_is_in_exclusive_backup(PG_FUNCTION_ARGS);
 
 #endif   /* XLOG_INTERNAL_H */
diff -ru postgresql/src/include/catalog/pg_proc.h postgresql-is_in_exclusive_backup-patch//src/include/catalog/pg_proc.h
--- postgresql/src/include/catalog/pg_proc.h	2012-01-26 23:01:32.340613398 +0100
+++ postgresql-is_in_exclusive_backup-patch//src/include/catalog/pg_proc.h	2012-03-01 10:48:48.068473056 +0100
@@ -2899,6 +2899,8 @@
 DESCR("prepare for taking an online backup");
 DATA(insert OID = 2173 ( pg_stop_backup			PGNSP PGUID 12 1 0 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_stop_backup _null_ _null_ _null_ ));
 DESCR("finish taking an online backup");
+DATA(insert OID = 3882 (  pg_is_in_exclusive_backup		PGNSP PGUID 12 1 0 0 0 f f f t f v 0 0 16 "" _null_ _null_ _null_ _null_ pg_is_in_backup _null_ _null_ _null_ ));
+DESCR("true if server is in on-line backup");
 DATA(insert OID = 2848 ( pg_switch_xlog			PGNSP PGUID 12 1 0 0 0 f f f t f v 0 0 25 "" _null_ _null_ _null_ _null_ pg_switch_xlog _null_ _null_ _null_ ));
 DESCR("switch to new xlog file");
 DATA(insert OID = 3098 ( pg_create_restore_point	PGNSP PGUID 12 1 0 0 0 f f f t f v 1 0 25 "25" _null_ _null_ _null_ _null_ pg_create_restore_point _null_ _null_ _null_ ));