Add operator strategy and comparison-value datatype fields to ScanKey.

Remove the 'strategy map' code, which was a large amount of mechanism
that no longer had any use except reverse-mapping from procedure OID to
strategy number.  Passing the strategy number to the index AM in the
first place is simpler and faster.
This is a preliminary step in planned support for cross-datatype index
operations.  I'm committing it now since the ScanKeyEntryInitialize()
API change touches quite a lot of files, and I want to commit those
changes before the tree drifts under me.

src/include/access/skey.h

@@ -7,10 +7,8 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: skey.h,v 1.22 2003/08/04 02:40:10 momjian Exp $
+ * $Id: skey.h,v 1.23 2003/11/09 21:30:37 tgl Exp $
  *
- * Note:
- *		Needs more accessor/assignment routines.
  *-------------------------------------------------------------------------
  */
 #ifndef SKEY_H
@@ -20,32 +18,77 @@
 #include "fmgr.h"
 
 
+/*
+ * Strategy numbers identify the semantics that particular operators have
+ * with respect to particular operator classes.
+ */
+typedef uint16 StrategyNumber;
+
+#define InvalidStrategy ((StrategyNumber) 0)
+
+/*
+ * We define the strategy numbers for B-tree indexes here, to avoid having
+ * to import access/nbtree.h into a lot of places that shouldn't need it.
+ */
+#define BTLessStrategyNumber			1
+#define BTLessEqualStrategyNumber		2
+#define BTEqualStrategyNumber			3
+#define BTGreaterEqualStrategyNumber	4
+#define BTGreaterStrategyNumber			5
+
+#define BTMaxStrategyNumber				5
+
+
+/*
+ * A ScanKey represents the application of a comparison operator between
+ * a table or index column and a constant.  When it's part of an array of
+ * ScanKeys, the comparison conditions are implicitly ANDed.  The index
+ * column is the left argument of the operator, if it's a binary operator.
+ * (The data structure can support unary indexable operators too; in that
+ * case sk_argument would go unused.  This is not currently implemented.)
+ *
+ * For an index scan, sk_strategy must be set correctly for the operator.
+ * When using a ScanKey in a heap scan, sk_strategy is not used and may be
+ * set to InvalidStrategy.
+ *
+ * Note: in some places, ScanKeys are used as a convenient representation
+ * for the invocation of an access method support procedure.  In this case
+ * sk_strategy is not meaningful, and sk_func may refer to a function that
+ * returns something other than boolean.
+ */
 typedef struct ScanKeyData
 {
-	bits16		sk_flags;		/* flags */
-	AttrNumber	sk_attno;		/* domain number */
-	RegProcedure sk_procedure;	/* procedure OID */
-	FmgrInfo	sk_func;		/* fmgr call info for procedure */
+	int			sk_flags;		/* flags, see below */
+	AttrNumber	sk_attno;		/* table or index column number */
+	StrategyNumber sk_strategy;	/* operator strategy number */
+	FmgrInfo	sk_func;		/* lookup info for function to call */
 	Datum		sk_argument;	/* data to compare */
+	Oid			sk_argtype;		/* datatype of sk_argument */
 } ScanKeyData;
 
 typedef ScanKeyData *ScanKey;
 
-/* ScanKeyData flags */
-#define SK_ISNULL		0x1		/* sk_argument is NULL */
-#define SK_UNARY		0x2		/* unary function (currently unsupported) */
-#define SK_NEGATE		0x4		/* negate function result */
-#define SK_COMMUTE		0x8		/* commute function (not fully supported) */
+/* ScanKeyData sk_flags */
+#define SK_ISNULL		0x0001	/* sk_argument is NULL */
+#define SK_UNARY		0x0002	/* unary operator (currently unsupported) */
 
 
 /*
  * prototypes for functions in access/common/scankey.c
  */
-extern void ScanKeyEntrySetIllegal(ScanKey entry);
-extern void ScanKeyEntryInitialize(ScanKey entry, bits16 flags,
-	 AttrNumber attributeNumber, RegProcedure procedure, Datum argument);
-extern void ScanKeyEntryInitializeWithInfo(ScanKey entry, bits16 flags,
-							 AttrNumber attributeNumber, FmgrInfo *finfo,
-							   MemoryContext mcxt, Datum argument);
+extern void ScanKeyEntryInitialize(ScanKey entry,
+								   int flags,
+								   AttrNumber attributeNumber,
+								   StrategyNumber strategy,
+								   RegProcedure procedure,
+								   Datum argument,
+								   Oid argtype);
+extern void ScanKeyEntryInitializeWithInfo(ScanKey entry,
+										   int flags,
+										   AttrNumber attributeNumber,
+										   StrategyNumber strategy,
+										   FmgrInfo *finfo,
+										   Datum argument,
+										   Oid argtype);
 
 #endif   /* SKEY_H */