Create a 'type cache' that keeps track of the data needed for any particular

datatype by array_eq and array_cmp; use this to solve problems with memory
leaks in array indexing support.  The parser's equality_oper and ordering_oper
routines also use the cache.  Change the operator search algorithms to look
for appropriate btree or hash index opclasses, instead of assuming operators
named '<' or '=' have the right semantics.  (ORDER BY ASC/DESC now also look
at opclasses, instead of assuming '<' and '>' are the right things.)  Add
several more index opclasses so that there is no regression in functionality
for base datatypes.  initdb forced due to catalog additions.

src/include/utils/typcache.h

@@ -0,0 +1,66 @@
+/*-------------------------------------------------------------------------
+ *
+ * typcache.h
+ *	  Type cache definitions.
+ *
+ * The type cache exists to speed lookup of certain information about data
+ * types that is not directly available from a type's pg_type row.
+ *
+ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * $Id: typcache.h,v 1.1 2003/08/17 19:58:06 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TYPCACHE_H
+#define TYPCACHE_H
+
+#include "fmgr.h"
+
+
+typedef struct TypeCacheEntry
+{
+	/* typeId is the hash lookup key and MUST BE FIRST */
+	Oid			type_id;		/* OID of the data type */
+
+	/* some subsidiary information copied from the pg_type row */
+	int16		typlen;
+	bool		typbyval;
+	char		typalign;
+
+	/*
+	 * Information obtained from opclass entries
+	 *
+	 * These will be InvalidOid if no match could be found, or if the
+	 * information hasn't yet been requested.
+	 */
+	Oid			btree_opc;		/* OID of the default btree opclass */
+	Oid			hash_opc;		/* OID of the default hash opclass */
+	Oid			eq_opr;			/* OID of the equality operator */
+	Oid			lt_opr;			/* OID of the less-than operator */
+	Oid			gt_opr;			/* OID of the greater-than operator */
+	Oid			cmp_proc;		/* OID of the btree comparison function */
+
+	/*
+	 * Pre-set-up fmgr call info for the equality operator and the btree
+	 * comparison function.  These are kept in the type cache to avoid
+	 * problems with memory leaks in repeated calls to array_eq and array_cmp.
+	 * There is not currently a need to maintain call info for the lt_opr
+	 * or gt_opr.
+	 */
+	FmgrInfo	eq_opr_finfo;
+	FmgrInfo	cmp_proc_finfo;
+} TypeCacheEntry;
+
+/* Bit flags to indicate which fields a given caller needs to have set */
+#define TYPECACHE_EQ_OPR			0x0001
+#define TYPECACHE_LT_OPR			0x0002
+#define TYPECACHE_GT_OPR			0x0004
+#define TYPECACHE_CMP_PROC			0x0008
+#define TYPECACHE_EQ_OPR_FINFO		0x0010
+#define TYPECACHE_CMP_PROC_FINFO	0x0020
+
+extern TypeCacheEntry *lookup_type_cache(Oid type_id, int flags);
+
+#endif   /* TYPCACHE_H */