Improve our #include situation by moving pointer types away from the

corresponding struct definitions.  This allows other headers to avoid including
certain highly-loaded headers such as rel.h and relscan.h, instead using just
relcache.h, heapam.h or genam.h, which are more lightweight and thus cause less
unnecessary dependencies.

src/include/access/genam.h

@@ -7,19 +7,20 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/genam.h,v 1.73 2008/06/08 22:41:04 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/genam.h,v 1.74 2008/06/19 00:46:05 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef GENAM_H
 #define GENAM_H
 
-#include "access/relscan.h"
 #include "access/sdir.h"
+#include "access/skey.h"
 #include "nodes/tidbitmap.h"
 #include "storage/buf.h"
 #include "storage/lock.h"
-#include "utils/rel.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
 
 /*
  * Struct for statistics returned by ambuild
@@ -73,21 +74,21 @@ typedef struct IndexBulkDeleteResult
 /* Typedef for callback function to determine if a tuple is bulk-deletable */
 typedef bool (*IndexBulkDeleteCallback) (ItemPointer itemptr, void *state);
 
-/* Struct for heap-or-index scans of system tables */
-typedef struct SysScanDescData
-{
-	Relation	heap_rel;		/* catalog being scanned */
-	Relation	irel;			/* NULL if doing heap scan */
-	HeapScanDesc scan;			/* only valid in heap-scan case */
-	IndexScanDesc iscan;		/* only valid in index-scan case */
-} SysScanDescData;
-
-typedef SysScanDescData *SysScanDesc;
+/* struct definitions appear in relscan.h */
+typedef struct IndexScanDescData *IndexScanDesc;
+typedef struct SysScanDescData *SysScanDesc;
 
 
 /*
  * generalized index_ interface routines (in indexam.c)
  */
+
+/*
+ * IndexScanIsValid
+ *		True iff the index scan is valid.
+ */
+#define IndexScanIsValid(scan) PointerIsValid(scan)
+
 extern Relation index_open(Oid relationId, LOCKMODE lockmode);
 extern void index_close(Relation relation, LOCKMODE lockmode);