Restructure pg_opclass, pg_amop, and pg_amproc per previous discussions in

pgsql-hackers.  pg_opclass now has a row for each opclass supported by each
index AM, not a row for each opclass name.  This allows pg_opclass to show
directly whether an AM supports an opclass, and furthermore makes it possible
to store additional information about an opclass that might be AM-dependent.
pg_opclass and pg_amop now store "lossy" and "haskeytype" information that we
previously expected the user to remember to provide in CREATE INDEX commands.
Lossiness is no longer an index-level property, but is associated with the
use of a particular operator in a particular index opclass.

Along the way, IndexSupportInitialize now uses the syscaches to retrieve
pg_amop and pg_amproc entries.  I find this reduces backend launch time by
about ten percent, at the cost of a couple more special cases in catcache.c's
IndexScanOK.

Initial work by Oleg Bartunov and Teodor Sigaev, further hacking by Tom Lane.

initdb forced.

src/tutorial/syscat.source

@@ -7,7 +7,7 @@
 -- Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 -- Portions Copyright (c) 1994, Regents of the University of California
 --
--- $Id: syscat.source,v 1.4 2001/06/13 19:31:56 tgl Exp $
+-- $Id: syscat.source,v 1.5 2001/08/21 16:36:06 tgl Exp $
 --
 ---------------------------------------------------------------------------
 
@@ -141,8 +141,8 @@ SELECT a.aggname, t.typname
 -- classes
 --
 SELECT am.amname, opc.opcname, opr.oprname
-  FROM pg_am am, pg_amop amop, pg_opclass opc, pg_operator opr
-  WHERE amop.amopid = am.oid
+  FROM pg_am am, pg_opclass opc, pg_amop amop, pg_operator opr
+  WHERE opc.opcamid = am.oid
     and amop.amopclaid = opc.oid
     and amop.amopopr = opr.oid
   ORDER BY amname, opcname, oprname;