diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 0cf4988..b030e1c 100644
*** a/src/backend/postmaster/pgstat.c
--- b/src/backend/postmaster/pgstat.c
*************** static void pgstat_write_statsfiles(bool
*** 259,265 ****
  static void pgstat_write_db_statsfile(PgStat_StatDBEntry *dbentry, bool permanent);
  static HTAB *pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep);
  static void pgstat_read_db_statsfile(Oid databaseid, HTAB *tabhash, HTAB *funchash, bool permanent);
! static void backend_read_statsfile(void);
  static void pgstat_read_current_status(void);
  
  static bool pgstat_write_statsfile_needed(void);
--- 259,265 ----
  static void pgstat_write_db_statsfile(PgStat_StatDBEntry *dbentry, bool permanent);
  static HTAB *pgstat_read_statsfiles(Oid onlydb, bool permanent, bool deep);
  static void pgstat_read_db_statsfile(Oid databaseid, HTAB *tabhash, HTAB *funchash, bool permanent);
! static void backend_read_statsfile(bool for_vacuum_stat);
  static void pgstat_read_current_status(void);
  
  static bool pgstat_write_statsfile_needed(void);
*************** pgstat_vacuum_stat(void)
*** 951,959 ****
  
  	/*
  	 * If not done for this transaction, read the statistics collector stats
! 	 * file into some hash tables.
  	 */
! 	backend_read_statsfile();
  
  	/*
  	 * Read pg_database and make a list of OIDs of all existing databases
--- 951,962 ----
  
  	/*
  	 * If not done for this transaction, read the statistics collector stats
! 	 * file into some hash tables.  We are willing to accept stats that are
! 	 * more stale than usual here.  (Since VACUUM never runs in a transaction
! 	 * block, this cannot result in accepting stale stats that would be used
! 	 * for other purposes later in the transaction.)
  	 */
! 	backend_read_statsfile(true);
  
  	/*
  	 * Read pg_database and make a list of OIDs of all existing databases
*************** pgstat_fetch_stat_dbentry(Oid dbid)
*** 2182,2188 ****
  	 * If not done for this transaction, read the statistics collector stats
  	 * file into some hash tables.
  	 */
! 	backend_read_statsfile();
  
  	/*
  	 * Lookup the requested database; return NULL if not found
--- 2185,2191 ----
  	 * If not done for this transaction, read the statistics collector stats
  	 * file into some hash tables.
  	 */
! 	backend_read_statsfile(false);
  
  	/*
  	 * Lookup the requested database; return NULL if not found
*************** pgstat_fetch_stat_tabentry(Oid relid)
*** 2213,2219 ****
  	 * If not done for this transaction, read the statistics collector stats
  	 * file into some hash tables.
  	 */
! 	backend_read_statsfile();
  
  	/*
  	 * Lookup our database, then look in its table hash table.
--- 2216,2222 ----
  	 * If not done for this transaction, read the statistics collector stats
  	 * file into some hash tables.
  	 */
! 	backend_read_statsfile(false);
  
  	/*
  	 * Lookup our database, then look in its table hash table.
*************** pgstat_fetch_stat_funcentry(Oid func_id)
*** 2265,2271 ****
  	PgStat_StatFuncEntry *funcentry = NULL;
  
  	/* load the stats file if needed */
! 	backend_read_statsfile();
  
  	/* Lookup our database, then find the requested function.  */
  	dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId);
--- 2268,2274 ----
  	PgStat_StatFuncEntry *funcentry = NULL;
  
  	/* load the stats file if needed */
! 	backend_read_statsfile(false);
  
  	/* Lookup our database, then find the requested function.  */
  	dbentry = pgstat_fetch_stat_dbentry(MyDatabaseId);
*************** pgstat_fetch_stat_numbackends(void)
*** 2350,2356 ****
  PgStat_ArchiverStats *
  pgstat_fetch_stat_archiver(void)
  {
! 	backend_read_statsfile();
  
  	return &archiverStats;
  }
--- 2353,2359 ----
  PgStat_ArchiverStats *
  pgstat_fetch_stat_archiver(void)
  {
! 	backend_read_statsfile(false);
  
  	return &archiverStats;
  }
*************** pgstat_fetch_stat_archiver(void)
*** 2367,2373 ****
  PgStat_GlobalStats *
  pgstat_fetch_global(void)
  {
! 	backend_read_statsfile();
  
  	return &globalStats;
  }
--- 2370,2376 ----
  PgStat_GlobalStats *
  pgstat_fetch_global(void)
  {
! 	backend_read_statsfile(false);
  
  	return &globalStats;
  }
*************** done:
*** 4341,4349 ****
   * If not already done, read the statistics collector stats file into
   * some hash tables.  The results will be kept until pgstat_clear_snapshot()
   * is called (typically, at end of transaction).
   */
  static void
! backend_read_statsfile(void)
  {
  	TimestampTz min_ts = 0;
  	TimestampTz ref_ts = 0;
--- 4344,4357 ----
   * If not already done, read the statistics collector stats file into
   * some hash tables.  The results will be kept until pgstat_clear_snapshot()
   * is called (typically, at end of transaction).
+  *
+  * If for_vacuum_stat is true, we're doing this for pgstat_vacuum_stat,
+  * which does not really need up-to-date stats: it's only trying to flush
+  * obsolete stats entries.  So we accept older stats than we normally would,
+  * and don't bleat about failure to get fresh stats either.
   */
  static void
! backend_read_statsfile(bool for_vacuum_stat)
  {
  	TimestampTz min_ts = 0;
  	TimestampTz ref_ts = 0;
*************** backend_read_statsfile(void)
*** 4376,4385 ****
  			/*
  			 * We set the minimum acceptable timestamp to PGSTAT_STAT_INTERVAL
  			 * msec before now.  This indirectly ensures that the collector
! 			 * needn't write the file more often than PGSTAT_STAT_INTERVAL. In
! 			 * an autovacuum worker, however, we want a lower delay to avoid
! 			 * using stale data, so we use PGSTAT_RETRY_DELAY (since the
! 			 * number of workers is low, this shouldn't be a problem).
  			 *
  			 * We don't recompute min_ts after sleeping, except in the
  			 * unlikely case that cur_ts went backwards.  So we might end up
--- 4384,4392 ----
  			/*
  			 * We set the minimum acceptable timestamp to PGSTAT_STAT_INTERVAL
  			 * msec before now.  This indirectly ensures that the collector
! 			 * needn't write the file more often than PGSTAT_STAT_INTERVAL.
! 			 * For vacuum_stat purposes, though, up to 100 times the normal
! 			 * age is considered acceptable.
  			 *
  			 * We don't recompute min_ts after sleeping, except in the
  			 * unlikely case that cur_ts went backwards.  So we might end up
*************** backend_read_statsfile(void)
*** 4390,4398 ****
  			 * actually accept.
  			 */
  			ref_ts = cur_ts;
! 			if (IsAutoVacuumWorkerProcess())
  				min_ts = TimestampTzPlusMilliseconds(ref_ts,
! 													 -PGSTAT_RETRY_DELAY);
  			else
  				min_ts = TimestampTzPlusMilliseconds(ref_ts,
  													 -PGSTAT_STAT_INTERVAL);
--- 4397,4405 ----
  			 * actually accept.
  			 */
  			ref_ts = cur_ts;
! 			if (for_vacuum_stat)
  				min_ts = TimestampTzPlusMilliseconds(ref_ts,
! 												-100 * PGSTAT_STAT_INTERVAL);
  			else
  				min_ts = TimestampTzPlusMilliseconds(ref_ts,
  													 -PGSTAT_STAT_INTERVAL);
*************** backend_read_statsfile(void)
*** 4441,4447 ****
  		pg_usleep(PGSTAT_RETRY_DELAY * 1000L);
  	}
  
! 	if (count >= PGSTAT_POLL_LOOP_COUNT)
  		elog(WARNING, "pgstat wait timeout");
  
  	/*
--- 4448,4454 ----
  		pg_usleep(PGSTAT_RETRY_DELAY * 1000L);
  	}
  
! 	if (count >= PGSTAT_POLL_LOOP_COUNT && !for_vacuum_stat)
  		elog(WARNING, "pgstat wait timeout");
  
  	/*