Arrange to cache fmgr lookup information for an index's access method

routines in the index's relcache entry, instead of doing a fresh fmgr_info
on every index access.  We were already doing this for the index's opclass
support functions; not sure why we didn't think to do it for the AM
functions too.  This supersedes the former method of caching (only)
amgettuple in indexscan scan descriptors; it's an improvement because the
function lookup can be amortized across multiple statements instead of
being repeated for each statement.  Even though lookup for builtin
functions is pretty cheap, this seems to drop a percent or two off some
simple benchmarks.

src/backend/access/index/genam.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/index/genam.c,v 1.47 2005/04/14 20:03:23 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/index/genam.c,v 1.48 2005/05/27 23:31:20 tgl Exp $
  *
  * NOTES
  *	  many of the old access method routines have been turned into
@@ -86,6 +86,7 @@ RelationGetIndexScan(Relation indexRelation,
 	else
 		scan->keyData = NULL;
 
+	scan->is_multiscan = false;			/* caller may change this */
 	scan->kill_prior_tuple = false;
 	scan->ignore_killed_tuples = true;	/* default setting */
 	scan->keys_are_unique = false;		/* may be set by index AM */
@@ -101,10 +102,6 @@ RelationGetIndexScan(Relation indexRelation,
 	scan->xs_ctup.t_data = NULL;
 	scan->xs_cbuf = InvalidBuffer;
 
-	/* mark cached function lookup data invalid; it will be set later */
-	scan->fn_getnext.fn_oid = InvalidOid;
-	scan->fn_getmulti.fn_oid = InvalidOid;
-
 	scan->unique_tuple_pos = 0;
 	scan->unique_tuple_mark = 0;
 

src/backend/utils/cache/relcache.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.223 2005/05/11 01:26:02 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.224 2005/05/27 23:31:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -904,6 +904,9 @@ RelationInitIndexAccessInfo(Relation relation)
 	/*
 	 * Allocate arrays to hold data
 	 */
+	relation->rd_aminfo = (RelationAmInfo *)
+		MemoryContextAllocZero(indexcxt, sizeof(RelationAmInfo));
+
 	if (amstrategies > 0)
 		operator = (Oid *)
 			MemoryContextAllocZero(indexcxt,
@@ -931,8 +934,8 @@ RelationInitIndexAccessInfo(Relation relation)
 	relation->rd_supportinfo = supportinfo;
 
 	/*
-	 * Fill the operator and support procedure OID arrays. (supportinfo is
-	 * left as zeroes, and is filled on-the-fly when used)
+	 * Fill the operator and support procedure OID arrays.  (aminfo and
+	 * supportinfo are left as zeroes, and are filled on-the-fly when used)
 	 */
 	IndexSupportInitialize(relation->rd_indclass,
 						   operator, support,
@@ -3015,7 +3018,9 @@ load_relcache_init_file(void)
 
 			rel->rd_support = support;
 
-			/* add a zeroed support-fmgr-info vector */
+			/* set up zeroed fmgr-info vectors */
+			rel->rd_aminfo = (RelationAmInfo *)
+				MemoryContextAllocZero(indexcxt, sizeof(RelationAmInfo));
 			nsupport = relform->relnatts * am->amsupport;
 			rel->rd_supportinfo = (FmgrInfo *)
 				MemoryContextAllocZero(indexcxt, nsupport * sizeof(FmgrInfo));
@@ -3031,6 +3036,7 @@ load_relcache_init_file(void)
 			Assert(rel->rd_indclass == NULL);
 			Assert(rel->rd_am == NULL);
 			Assert(rel->rd_indexcxt == NULL);
+			Assert(rel->rd_aminfo == NULL);
 			Assert(rel->rd_operator == NULL);
 			Assert(rel->rd_support == NULL);
 			Assert(rel->rd_supportinfo == NULL);

src/include/access/genam.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/genam.h,v 1.50 2005/04/14 20:03:27 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/genam.h,v 1.51 2005/05/27 23:31:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -104,7 +104,7 @@ extern IndexBulkDeleteResult *index_vacuum_cleanup(Relation indexRelation,
 extern RegProcedure index_cost_estimator(Relation indexRelation);
 extern RegProcedure index_getprocid(Relation irel, AttrNumber attnum,
 				uint16 procnum);
-extern struct FmgrInfo *index_getprocinfo(Relation irel, AttrNumber attnum,
+extern FmgrInfo *index_getprocinfo(Relation irel, AttrNumber attnum,
 				  uint16 procnum);
 
 /*

src/include/access/relscan.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.38 2005/03/27 23:53:04 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.39 2005/05/27 23:31:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -40,9 +40,8 @@ typedef HeapScanDescData *HeapScanDesc;
 
 /*
  * We use the same IndexScanDescData structure for both amgettuple-based
- * and amgetmulti-based index scans.  Which one is being used can be told
- * by looking at fn_getnext and fn_getmulti, only one of which will be
- * initialized.  Some fields are only relevant in amgettuple-based scans.
+ * and amgetmulti-based index scans.  Some fields are only relevant in
+ * amgettuple-based scans.
  */
 typedef struct IndexScanDescData
 {
@@ -52,6 +51,7 @@ typedef struct IndexScanDescData
 	Snapshot	xs_snapshot;	/* snapshot to see */
 	int			numberOfKeys;	/* number of scan keys */
 	ScanKey		keyData;		/* array of scan key descriptors */
+	bool		is_multiscan;	/* TRUE = using amgetmulti */
 
 	/* signaling to index AM about killing index tuples */
 	bool		kill_prior_tuple;		/* last-returned tuple is dead */
@@ -75,9 +75,6 @@ typedef struct IndexScanDescData
 	Buffer		xs_cbuf;		/* current heap buffer in scan, if any */
 	/* NB: if xs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
 
-	FmgrInfo	fn_getnext;		/* cached lookup info for AM's getnext fn */
-	FmgrInfo	fn_getmulti;	/* cached lookup info for AM's getmulti fn */
-
 	/*
 	 * If keys_are_unique and got_tuple are both true, we stop calling the
 	 * index AM; it is then necessary for index_getnext to keep track of

src/include/utils/rel.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.83 2005/03/29 00:17:18 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/rel.h,v 1.84 2005/05/27 23:31:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,6 +18,7 @@
 #include "catalog/pg_am.h"
 #include "catalog/pg_class.h"
 #include "catalog/pg_index.h"
+#include "fmgr.h"
 #include "rewrite/prs2lock.h"
 #include "storage/block.h"
 #include "storage/relfilenode.h"
@@ -99,6 +100,27 @@ typedef struct PgStat_Info
 } PgStat_Info;
 
 
+/*
+ * Cached lookup information for the index access method functions defined
+ * by the pg_am row associated with an index relation.
+ */
+typedef struct RelationAmInfo
+{
+	FmgrInfo	aminsert;
+	FmgrInfo	ambeginscan;
+	FmgrInfo	amgettuple;
+	FmgrInfo	amgetmulti;
+	FmgrInfo	amrescan;
+	FmgrInfo	amendscan;
+	FmgrInfo	ammarkpos;
+	FmgrInfo	amrestrpos;
+	FmgrInfo	ambuild;
+	FmgrInfo	ambulkdelete;
+	FmgrInfo	amvacuumcleanup;
+	FmgrInfo	amcostestimate;
+} RelationAmInfo;
+
+
 /*
  * Here are the contents of a relation cache entry.
  */
@@ -150,11 +172,10 @@ typedef struct RelationData
 	 * that restriction.
 	 */
 	MemoryContext rd_indexcxt;	/* private memory cxt for this stuff */
+	RelationAmInfo *rd_aminfo;	/* lookup info for funcs found in pg_am */
 	Oid		   *rd_operator;	/* OIDs of index operators */
 	RegProcedure *rd_support;	/* OIDs of support procedures */
-	struct FmgrInfo *rd_supportinfo;	/* lookup info for support
-										 * procedures */
-	/* "struct FmgrInfo" avoids need to include fmgr.h here */
+	FmgrInfo   *rd_supportinfo;	/* lookup info for support procedures */
 	List	   *rd_indexprs;	/* index expression trees, if any */
 	List	   *rd_indpred;		/* index predicate tree, if any */