Redefining repl_status view to improve performance, also add an

index on repl_monitor to speed up even more the view.
damajor · Jun 13, 2011 · 4d26e4d · 4d26e4d
1 parent 3f4ff5a
commit 4d26e4d
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Showing 2 changed files with 25 additions and 14 deletions.
diff --git a/repmgr.c b/repmgr.c
@@ -1911,16 +1911,16 @@ create_schema(PGconn *conn)
 		exit(ERR_BAD_CONFIG);
 	}
 
-	/* and the view */
+	/* a view */
 	sqlquery_snprintf(sqlquery, "CREATE VIEW %s.repl_status AS "
-	                  "  WITH monitor_info AS (SELECT *, ROW_NUMBER() OVER (PARTITION BY primary_node, standby_node "
-	                  " ORDER BY last_monitor_time desc) "
-	                  "  FROM %s.repl_monitor) "
-	                  "  SELECT primary_node, standby_node, last_monitor_time, last_wal_primary_location, "
-	                  "         last_wal_standby_location, pg_size_pretty(replication_lag) replication_lag, "
-	                  "         pg_size_pretty(apply_lag) apply_lag, age(now(), last_monitor_time) AS time_lag "
-	                  "    FROM monitor_info a "
-	                  "   WHERE row_number = 1", repmgr_schema, repmgr_schema);
+	                  " SELECT primary_node, standby_node, last_monitor_time, last_wal_primary_location, "
+	                  "        last_wal_standby_location, pg_size_pretty(replication_lag) replication_lag, "
+	                  "        pg_size_pretty(apply_lag) apply_lag, "
+	                  "        age(now(), last_monitor_time) AS time_lag "
+	                  "   FROM %s.repl_monitor "
+	                  "  WHERE (standby_node, last_monitor_time) IN (SELECT standby_node, MAX(last_monitor_time) "
+	                  "                                                FROM %s.repl_monitor GROUP BY 1)",
+	                  repmgr_schema, repmgr_schema, repmgr_schema);
 	log_debug(_("master register: %s\n"), sqlquery);
 	if (!PQexec(conn, sqlquery))
 	{
@@ -1930,6 +1930,18 @@ create_schema(PGconn *conn)
 		exit(ERR_BAD_CONFIG);
 	}
 
+	/* an index to improve performance of the view */
+	sqlquery_snprintf(sqlquery, "CREATE INDEX idx_repl_status_sort "
+	                            "    ON %s.repl_monitor (last_monitor_time, standby_node) ");
+	log_debug(_("master register: %s\n"), sqlquery);
+	if (!PQexec(conn, sqlquery))
+	{
+		log_err(_("Cannot indexing table %s.repl_monitor: %s\n"),
+		        repmgr_schema, PQerrorMessage(conn));
+		PQfinish(conn);
+		exit(ERR_BAD_CONFIG);
+	}
+
 	/* XXX Here we MUST try to load the repmgr_function.sql not hardcode it here */
 	sprintf(sqlquery,
 	        "CREATE OR REPLACE FUNCTION public.repmgr_update_standby_location(text) RETURNS boolean "

diff --git a/repmgr.sql b/repmgr.sql
@@ -34,6 +34,7 @@ CREATE TABLE repl_monitor (
 );
 ALTER TABLE repl_monitor OWNER TO repmgr;
 
+CREATE INDEX idx_repl_monitor_last_monitor_sort ON repl_monitor(last_monitor_time, standby_node);
 
 /*
  * This view shows the latest monitor info about every node.
@@ -46,14 +47,12 @@ ALTER TABLE repl_monitor OWNER TO repmgr;
  * time_lag: how many seconds are we from being up-to-date with master
  */
 CREATE VIEW repl_status AS
-WITH monitor_info AS (SELECT *, ROW_NUMBER() OVER (PARTITION BY primary_node, standby_node
-                                                       ORDER BY last_monitor_time desc)
-                        FROM repl_monitor)
 SELECT primary_node, standby_node, last_monitor_time, last_wal_primary_location,
        last_wal_standby_location, pg_size_pretty(replication_lag) replication_lag,
        pg_size_pretty(apply_lag) apply_lag,
        age(now(), last_monitor_time) AS time_lag
-  FROM monitor_info a
- WHERE row_number = 1;
+ FROM repl_monitor
+WHERE (standby_node, last_monitor_time) IN (SELECT standby_node, MAX(last_monitor_time)
+                                              FROM repl_monitor GROUP BY 1);
 
 ALTER VIEW repl_status OWNER TO repmgr;