Restructure local-buffer handling per recent pghackers discussion.

The local buffer manager is no longer used for newly-created relations
(unless they are TEMP); a new non-TEMP relation goes through the shared
bufmgr and thus will participate normally in checkpoints.  But TEMP relations
use the local buffer manager throughout their lifespan.  Also, operations
in TEMP relations are not logged in WAL, thus improving performance.
Since it's no longer necessary to fsync relations as they move out of the
local buffers into shared buffers, quite a lot of smgr.c/md.c/fd.c code
is no longer needed and has been removed: there's no concept of a dirty
relation anymore in md.c/fd.c, and we never fsync anything but WAL.
Still TODO: improve local buffer management algorithms so that it would
be reasonable to increase NLocBuffer.

src/include/utils/rel.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: rel.h,v 1.60 2002/06/20 20:29:53 momjian Exp $
+ * $Id: rel.h,v 1.61 2002/08/06 02:36:35 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -112,10 +112,10 @@ typedef struct RelationData
 	BlockNumber rd_targblock;	/* current insertion target block, or
 								 * InvalidBlockNumber */
 	int			rd_refcnt;		/* reference count */
-	bool		rd_myxactonly;	/* rel uses the local buffer mgr */
+	bool		rd_isnew;		/* rel was created in current xact */
+	bool		rd_istemp;		/* rel uses the local buffer mgr */
 	bool		rd_isnailed;	/* rel is nailed in cache */
 	bool		rd_indexfound;	/* true if rd_indexlist is valid */
-	bool		rd_uniqueindex; /* true if rel is a UNIQUE index */
 	Form_pg_class rd_rel;		/* RELATION tuple */
 	TupleDesc	rd_att;			/* tuple descriptor */
 	Oid			rd_id;			/* relation's object id */