Cache fmgr lookup data for index's getnext() function in IndexScanDesc,

so that the fmgr lookup only has to happen once per index scan and not
once per tuple.  Seems to save 5% or so of CPU time for an indexscan.

Author: tglsfdc

src/backend/access/index/genam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/index/genam.c,v 1.23 2000/01/26 05:55:57 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/index/genam.c,v 1.24 2000/03/14 23:52:01 tgl Exp $
  *
  * NOTES
  *	  many of the old access method routines have been turned into
@@ -114,6 +114,9 @@ RelationGetIndexScan(Relation relation,
 	ItemPointerSetInvalid(&scan->currentMarkData);
 	ItemPointerSetInvalid(&scan->nextMarkData);
 
+	/* mark cached function lookup data invalid; it will be set on first use */
+	scan->fn_getnext.fn_oid = InvalidOid;
+
 	if (numberOfKeys > 0)
 		scan->keyData = (ScanKey) palloc(sizeof(ScanKeyData) * numberOfKeys);
 	else

src/backend/access/index/indexam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/index/indexam.c,v 1.40 2000/01/26 05:55:57 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/index/indexam.c,v 1.41 2000/03/14 23:52:01 tgl Exp $
  *
  * INTERFACE ROUTINES
  *		index_open		- open an index relation by relationId
@@ -329,17 +329,28 @@ RetrieveIndexResult
 index_getnext(IndexScanDesc scan,
 			  ScanDirection direction)
 {
-	RegProcedure procedure;
 	RetrieveIndexResult result;
 
 	SCAN_CHECKS;
-	GET_SCAN_PROCEDURE(getnext, amgettuple);
+
+	/* ----------------
+	 *	Look up the access procedure only once per scan.
+	 * ----------------
+	 */
+	if (scan->fn_getnext.fn_oid == InvalidOid)
+	{
+		RegProcedure procedure;
+
+		GET_SCAN_PROCEDURE(getnext, amgettuple);
+		fmgr_info(procedure, &scan->fn_getnext);
+	}
 
 	/* ----------------
 	 *	have the am's gettuple proc do all the work.
 	 * ----------------
 	 */
-	result = (RetrieveIndexResult) fmgr(procedure, scan, direction);
+	result = (RetrieveIndexResult)
+		(*fmgr_faddr(&scan->fn_getnext)) (scan, direction);
 
 	return result;
 }

src/include/access/relscan.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: relscan.h,v 1.18 2000/01/26 05:57:51 momjian Exp $
+ * $Id: relscan.h,v 1.19 2000/03/14 23:52:00 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,6 +54,7 @@ typedef struct IndexScanDescData
 	bool		scanFromEnd;	/* restart scan at end? */
 	uint16		numberOfKeys;	/* number of key attributes */
 	ScanKey		keyData;		/* key descriptor */
+	FmgrInfo	fn_getnext;		/* cached lookup info for am's getnext fn */
 } IndexScanDescData;
 
 typedef IndexScanDescData *IndexScanDesc;