Flush any remaining statistics counts out to the collector at process

exit.  Without this, operations triggered during backend exit (such as
temp table deletions) won't be counted ... which given heavy usage of
temp tables can lead to pg_autovacuum falling way behind on the need
to vacuum pg_class and pg_attribute.  Per reports from Steve Crawford
and others.

src/backend/postmaster/pgstat.c

@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2005, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.88 2005/03/25 00:34:21 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.89 2005/03/31 23:20:49 tgl Exp $
  * ----------
  */
 #include "postgres.h"
@@ -160,6 +160,7 @@ NON_EXEC_STATIC void PgstatCollectorMain(int argc, char *argv[]);
 static void pgstat_recvbuffer(void);
 static void pgstat_exit(SIGNAL_ARGS);
 static void pgstat_die(SIGNAL_ARGS);
+static void pgstat_beshutdown_hook(int code, Datum arg);
 
 static int	pgstat_add_backend(PgStat_MsgHdr *msg);
 static void pgstat_sub_backend(int procpid);
@@ -670,6 +671,25 @@ pgstat_bestart(void)
 
 	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_BESTART);
 	pgstat_send(&msg, sizeof(msg));
+
+	/*
+	 * Set up a process-exit hook to ensure we flush the last batch of
+	 * statistics to the collector.
+	 */
+	on_proc_exit(pgstat_beshutdown_hook, 0);
+}
+
+/*
+ * Flush any remaining statistics counts out to the collector at process
+ * exit.   Without this, operations triggered during backend exit (such as
+ * temp table deletions) won't be counted.  This is an on_proc_exit hook,
+ * not on_shmem_exit, so that everything interesting must have happened
+ * already.
+ */
+static void
+pgstat_beshutdown_hook(int code, Datum arg)
+{
+	pgstat_report_tabstat();
 }