The following patch should allow UPDATE_INTERVAL to be specified on the

command line. We find this useful because we frequently deal with
thousands of tables in an environment where neither the databases nor
the tables are updated frequently. This helps allow us to cut down on
the overhead of updating the list for every other primary loop of
pg_autovacuum.

I chose -i as the command-line argument and documented it briefly in
the README.

The patch was applied to the 7.4.7 version of pg_autovacuum in contrib.

Thomas F.O'Connell

contrib/pg_autovacuum/README.pg_autovacuum

@@ -123,6 +123,10 @@ pg_autovacuum has the following optional arguments:
 -V vacuum scaling factor: see "Vacuum and Analyze" below.
 -a analyze base threshold: see "Vacuum and Analyze" below.
 -A analyze scaling factor: see "Vacuum and Analyze" below.
+-i update interval: how often (in terms of iterations of the primary loop
+   over the database list) to update the database list. The default is 2,
+   which means the list will be updated before every other pass through
+   the database list.
 -L log file: Name of file to which output is submitted, otherwise STDERR
 -U username: Username pg_autovacuum will use to connect with, if not
    specified the current username is used.
@@ -157,6 +161,7 @@ the time of writing they are:
 -A 1   (half of -V if not specified)
 -s 300 (5 minutes)
 -S 2
+-i 2
 
 The following arguments are used on Windows only:
 

contrib/pg_autovacuum/pg_autovacuum.c

@@ -4,7 +4,7 @@
  * Revisions by Christopher B. Browne, Liberty RMS
  * Win32 Service code added by Dave Page
  *
- * $PostgreSQL: pgsql/contrib/pg_autovacuum/pg_autovacuum.c,v 1.30 2005/04/03 00:01:51 tgl Exp $
+ * $PostgreSQL: pgsql/contrib/pg_autovacuum/pg_autovacuum.c,v 1.31 2005/04/19 03:35:15 momjian Exp $
  */
 
 #include "postgres_fe.h"
@@ -1103,6 +1103,7 @@ get_cmd_args(int argc, char *argv[])
 	args->analyze_base_threshold = -1;
 	args->analyze_scaling_factor = -1;
 	args->debug = AUTOVACUUM_DEBUG;
+	args->update_interval = UPDATE_INTERVAL;
 #ifndef WIN32
 	args->daemonize = 0;
 #else
@@ -1157,6 +1158,9 @@ get_cmd_args(int argc, char *argv[])
 			case 'A':
 				args->analyze_scaling_factor = atof(optarg);
 				break;
+			case 'i':
+				args->update_interval = atoi(optarg);
+				break;
 			case 'c':
 				args->av_vacuum_cost_delay = atoi(optarg);
 				break;
@@ -1341,6 +1345,8 @@ print_cmd_args(void)
 	log_entry(logbuffer, LVL_INFO);
 	sprintf(logbuffer, "  args->analyze_scaling_factor=%f", args->analyze_scaling_factor);
 	log_entry(logbuffer, LVL_INFO);
+	sprintf(logbuffer, "  args->update_interval=%i", args->update_interval);
+	log_entry(logbuffer, LVL_INFO);
 
 	if (args->av_vacuum_cost_delay != -1)
 		sprintf(logbuffer, "  args->av_vacuum_cost_delay=%d", args->av_vacuum_cost_delay);
@@ -1646,8 +1652,8 @@ VacuumLoop(int argc, char **argv)
 			}
 		}
 
-		if (loops % UPDATE_INTERVAL == 0)		/* Update the list if it's
-												 * time */
+		if (loops % args->update_interval == 0)		/* Update the list if it's
+													 * time */
 			update_db_list(db_list);	/* Add and remove databases from
 										 * the list */
 
@@ -1661,8 +1667,8 @@ VacuumLoop(int argc, char **argv)
 
 			if (dbs->conn != NULL)
 			{
-				if (loops % UPDATE_INTERVAL == 0)		/* Update the list if
-														 * it's time */
+				if (loops % args->update_interval == 0)		/* Update the list if
+															 * it's time */
 					update_table_list(dbs);		/* Add and remove tables
 												 * from the list */
 

contrib/pg_autovacuum/pg_autovacuum.h

@@ -2,7 +2,7 @@
  * Header file for pg_autovacuum.c
  * (c) 2003 Matthew T. O'Connor
  *
- * $PostgreSQL: pgsql/contrib/pg_autovacuum/pg_autovacuum.h,v 1.14 2004/12/02 22:48:10 momjian Exp $
+ * $PostgreSQL: pgsql/contrib/pg_autovacuum/pg_autovacuum.h,v 1.15 2005/04/19 03:35:15 momjian Exp $
  */
 
 #ifndef _PG_AUTOVACUUM_H
@@ -44,6 +44,7 @@ typedef struct cmdargs
 {
 	int			vacuum_base_threshold,
 				analyze_base_threshold,
+				update_interval,
 				sleep_base_value,
 				debug,