Don't reset pg_class.reltuples and relpages in VACUUM, if any pages were

skipped. We could update relpages anyway, but it seems better to only
update it together with reltuples, because we use the reltuples/relpages
ratio in the planner. Also don't update n_live_tuples in pgstat.

ANALYZE in VACUUM ANALYZE now needs to update pg_class, if the
VACUUM-phase didn't do so. Added some boolean-passing to let analyze_rel
know if it should update pg_class or not.

I also moved the relcache invalidation (to update rd_targblock) from
vac_update_relstats to where RelationTruncate is called, because
vac_update_relstats is not called for partial vacuums anymore. It's more
obvious to send the invalidation close to the truncation that requires it.

Per report by Ned T. Crigler.

src/include/commands/vacuum.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.81 2008/11/10 00:49:37 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/commands/vacuum.h,v 1.82 2008/12/17 09:15:03 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -144,10 +144,10 @@ extern void vacuum_delay_point(void);
 
 /* in commands/vacuumlazy.c */
 extern void lazy_vacuum_rel(Relation onerel, VacuumStmt *vacstmt,
-				BufferAccessStrategy bstrategy);
+				BufferAccessStrategy bstrategy, bool *scanned_all);
 
 /* in commands/analyze.c */
 extern void analyze_rel(Oid relid, VacuumStmt *vacstmt,
-			BufferAccessStrategy bstrategy);
+			BufferAccessStrategy bstrategy, bool update_reltuples);
 
 #endif   /* VACUUM_H */