Restructure operator classes to allow improved handling of cross-data-type

cases.  Operator classes now exist within "operator families".  While most
families are equivalent to a single class, related classes can be grouped
into one family to represent the fact that they are semantically compatible.
Cross-type operators are now naturally adjunct parts of a family, without
having to wedge them into a particular opclass as we had done originally.

This commit restructures the catalogs and cleans up enough of the fallout so
that everything still works at least as well as before, but most of the work
needed to actually improve the planner's behavior will come later.  Also,
there are not yet CREATE/DROP/ALTER OPERATOR FAMILY commands; the only way
to create a new family right now is to allow CREATE OPERATOR CLASS to make
one by default.  I owe some more documentation work, too.  But that can all
be done in smaller pieces once this infrastructure is in place.

src/include/utils/rel.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.92 2006/10/04 00:30:10 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.93 2006/12/23 00:43:13 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -165,16 +165,15 @@ typedef struct RelationData
 	Form_pg_index rd_index;		/* pg_index tuple describing this index */
 	struct HeapTupleData *rd_indextuple;		/* all of pg_index tuple */
 	/* "struct HeapTupleData *" avoids need to include htup.h here	*/
-	oidvector  *rd_indclass;	/* extracted pointer to rd_index field */
 	Form_pg_am	rd_am;			/* pg_am tuple for index's AM */
 
 	/*
 	 * index access support info (used only for an index relation)
 	 *
 	 * Note: only default operators and support procs for each opclass are
-	 * cached, namely those with subtype zero.	The arrays are indexed by
-	 * strategy or support number, which is a sufficient identifier given that
-	 * restriction.
+	 * cached, namely those with lefttype and righttype equal to the opclass's
+	 * opcintype.  The arrays are indexed by strategy or support number,
+	 * which is a sufficient identifier given that restriction.
 	 *
 	 * Note: rd_amcache is available for index AMs to cache private data about
 	 * an index.  This must be just a cache since it may get reset at any time
@@ -185,6 +184,8 @@ typedef struct RelationData
 	 */
 	MemoryContext rd_indexcxt;	/* private memory cxt for this stuff */
 	RelationAmInfo *rd_aminfo;	/* lookup info for funcs found in pg_am */
+	Oid		   *rd_opfamily;	/* OIDs of op families for each index col */
+	Oid		   *rd_opcintype;	/* OIDs of opclass declared input data types */
 	Oid		   *rd_operator;	/* OIDs of index operators */
 	RegProcedure *rd_support;	/* OIDs of support procedures */
 	FmgrInfo   *rd_supportinfo; /* lookup info for support procedures */