Add pg_switch_wal(). It is used for page backup

za-arthur · za-arthur · commit 2bdaaf0eaf2a · 2017-04-24T19:25:42.000+03:00
diff --git a/backup.c b/backup.c
@@ -59,6 +59,7 @@ static void backup_files(void *arg);
 static void do_backup_database(parray *backup_list);
 
 static void pg_start_backup(const char *label, bool smooth, pgBackup *backup);
+static void pg_switch_wal(void);
 static void pg_stop_backup(pgBackup *backup);
 
 static void add_pgdata_files(parray *files, const char *root);
@@ -214,6 +215,16 @@ do_backup_database(parray *backup_list)
 	 */
 	if (current.backup_mode == BACKUP_MODE_DIFF_PAGE)
 	{
+		/*
+		 * Switch to a new WAL segment. It is necessary to get archived WAL
+		 * segment, which includes start LSN of current backup.
+		 *
+		 * Do not switch for standby node and if backup is stream.
+		 */
+		if (!from_replica && !stream_wal)
+			pg_switch_wal();
+		if (!stream_wal)
+			wait_archive_lsn(current.start_lsn, false);
 		/*
 		 * Build the page map. Obtain information about changed pages
 		 * reading WAL segments present in archives up to the point
@@ -581,14 +592,29 @@ pg_start_backup(const char *label, bool smooth, pgBackup *backup)
 	/* Calculate LSN */
 	backup->start_lsn = (XLogRecPtr) ((uint64) xlogid << 32) | xrecoff;
 
-	if (!stream_wal)
-		wait_archive_lsn(backup->start_lsn,
-						 /*
-						  * For backup from master wait for previous segment.
-						  * For backup from replica wait for current segment.
-						  */
-						 !from_replica);
+	PQclear(res);
+}
+
+/*
+ * Switch to a new WAL segment. It should be called only for master.
+ */
+static void
+pg_switch_wal(void)
+{
+	PGresult   *res;
+
+	/* Remove annoying NOTICE messages generated by backend */
+	res = pgut_execute(backup_conn, "SET client_min_messages = warning;", 0,
+					   NULL);
+	PQclear(res);
 
+#if PG_VERSION_NUM >= 100000
+	res = pgut_execute(backup_conn, "SELECT * FROM pg_switch_wal()", 0,
+					   NULL);
+#else
+	res = pgut_execute(backup_conn, "SELECT * FROM pg_switch_xlog()", 0,
+					   NULL);
+#endif
 	PQclear(res);
 }
 
