Restructure index AM interface for index building and index tuple deletion,

per previous discussion on pghackers.  Most of the duplicate code in
different AMs' ambuild routines has been moved out to a common routine
in index.c; this means that all index types now do the right things about
inserting recently-dead tuples, etc.  (I also removed support for EXTEND
INDEX in the ambuild routines, since that's about to go away anyway, and
it cluttered the code a lot.)  The retail indextuple deletion routines have
been replaced by a "bulk delete" routine in which the indexscan is inside
the access method.  I haven't pushed this change as far as it should go yet,
but it should allow considerable simplification of the internal bookkeeping
for deletions.  Also, add flag columns to pg_am to eliminate various
hardcoded tests on AM OIDs, and remove unused pg_am columns.

Fix rtree and gist index types to not attempt to store NULLs; before this,
gist usually crashed, while rtree managed not to crash but computed wacko
bounding boxes for NULL entries (which might have had something to do with
the performance problems we've heard about occasionally).

Add AtEOXact routines to hash, rtree, and gist, all of which have static
state that needs to be reset after an error.  We discovered this need long
ago for btree, but missed the other guys.

Oh, one more thing: concurrent VACUUM is now the default.

src/include/access/genam.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: genam.h,v 1.25 2001/01/24 19:43:19 momjian Exp $
+ * $Id: genam.h,v 1.26 2001/07/15 22:48:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,8 +18,21 @@
 #include "access/relscan.h"
 #include "access/sdir.h"
 
+
+/* Struct for statistics returned by bulk-delete operation */
+typedef struct IndexBulkDeleteResult
+{
+	BlockNumber	num_pages;		/* pages remaining in index */
+	double		tuples_removed;	/* # removed by bulk-delete operation */
+	double		num_index_tuples; /* # remaining */
+} IndexBulkDeleteResult;
+
+/* Typedef for callback function to determine if a tuple is bulk-deletable */
+typedef bool (*IndexBulkDeleteCallback) (ItemPointer itemptr, void *state);
+
+
 /* ----------------
- *		generalized index_ interface routines
+ *		generalized index_ interface routines (in indexam.c)
  * ----------------
  */
 extern Relation index_open(Oid relationId);
@@ -29,7 +42,6 @@ extern InsertIndexResult index_insert(Relation relation,
 			 Datum *datum, char *nulls,
 			 ItemPointer heap_t_ctid,
 			 Relation heapRel);
-extern void index_delete(Relation relation, ItemPointer indexItem);
 extern IndexScanDesc index_beginscan(Relation relation, bool scanFromEnd,
 				uint16 numberOfKeys, ScanKey key);
 extern void index_rescan(IndexScanDesc scan, bool scanFromEnd, ScanKey key);
@@ -38,6 +50,9 @@ extern void index_markpos(IndexScanDesc scan);
 extern void index_restrpos(IndexScanDesc scan);
 extern RetrieveIndexResult index_getnext(IndexScanDesc scan,
 			  ScanDirection direction);
+extern IndexBulkDeleteResult *index_bulk_delete(Relation relation,
+				IndexBulkDeleteCallback callback,
+				void *callback_state);
 extern RegProcedure index_cost_estimator(Relation relation);
 extern RegProcedure index_getprocid(Relation irel, AttrNumber attnum,
 				uint16 procnum);

src/include/access/gist.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: gist.h,v 1.28 2001/05/31 18:16:55 tgl Exp $
+ * $Id: gist.h,v 1.29 2001/07/15 22:48:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -162,7 +162,7 @@ typedef struct GISTENTRY
 /* gist.c */
 extern Datum gistbuild(PG_FUNCTION_ARGS);
 extern Datum gistinsert(PG_FUNCTION_ARGS);
-extern Datum gistdelete(PG_FUNCTION_ARGS);
+extern Datum gistbulkdelete(PG_FUNCTION_ARGS);
 extern void _gistdump(Relation r);
 extern void gistfreestack(GISTSTACK *s);
 extern void initGISTstate(GISTSTATE *giststate, Relation index);

src/include/access/gistscan.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: gistscan.h,v 1.15 2001/05/30 19:53:39 tgl Exp $
+ * $Id: gistscan.h,v 1.16 2001/07/15 22:48:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,5 +22,6 @@ extern Datum gistmarkpos(PG_FUNCTION_ARGS);
 extern Datum gistrestrpos(PG_FUNCTION_ARGS);
 extern Datum gistendscan(PG_FUNCTION_ARGS);
 extern void gistadjscans(Relation r, int op, BlockNumber blkno, OffsetNumber offnum);
+extern void AtEOXact_gist(void);
 
 #endif	 /* GISTSCAN_H */

src/include/access/hash.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: hash.h,v 1.38 2001/03/22 04:00:27 momjian Exp $
+ * $Id: hash.h,v 1.39 2001/07/15 22:48:18 tgl Exp $
  *
  * NOTES
  *		modeled after Margo Seltzer's hash implementation for unix.
@@ -55,7 +55,7 @@ typedef uint32 PageOffset;
 #define OADDR_OF(S,O)	((OverflowPageAddress)((uint32)((uint32)(S) << SPLITSHIFT) + (O)))
 
 #define BUCKET_TO_BLKNO(B) \
-		((Bucket) ((B) + ((B) ? metap->SPARES[_hash_log2((B)+1)-1] : 0)) + 1)
+		((Bucket) ((B) + ((B) ? metap->hashm_spares[_hash_log2((B)+1)-1] : 0)) + 1)
 #define OADDR_TO_BLKNO(B)		 \
 		((BlockNumber) \
 		 (BUCKET_TO_BLKNO ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B))));
@@ -165,16 +165,6 @@ typedef struct HashMetaPageData
 
 typedef HashMetaPageData *HashMetaPage;
 
-/* Short hands for accessing structure */
-#define OVFL_POINT		hashm_ovflpoint
-#define LAST_FREED		hashm_lastfreed
-#define MAX_BUCKET		hashm_maxbucket
-#define FFACTOR			hashm_ffactor
-#define HIGH_MASK		hashm_highmask
-#define LOW_MASK		hashm_lowmask
-#define NKEYS			hashm_nkeys
-#define SPARES			hashm_spares
-
 extern bool BuildingHash;
 
 typedef struct HashItemData
@@ -256,7 +246,7 @@ extern Datum hashrescan(PG_FUNCTION_ARGS);
 extern Datum hashendscan(PG_FUNCTION_ARGS);
 extern Datum hashmarkpos(PG_FUNCTION_ARGS);
 extern Datum hashrestrpos(PG_FUNCTION_ARGS);
-extern Datum hashdelete(PG_FUNCTION_ARGS);
+extern Datum hashbulkdelete(PG_FUNCTION_ARGS);
 
 /*
  * Datatype-specific hash functions in hashfunc.c.
@@ -310,6 +300,7 @@ extern void _hash_expandtable(Relation rel, Buffer metabuf);
 extern void _hash_regscan(IndexScanDesc scan);
 extern void _hash_dropscan(IndexScanDesc scan);
 extern void _hash_adjscans(Relation rel, ItemPointer tid);
+extern void AtEOXact_hash(void);
 
 
 /* hashsearch.c */

src/include/access/nbtree.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: nbtree.h,v 1.55 2001/03/22 04:00:29 momjian Exp $
+ * $Id: nbtree.h,v 1.56 2001/07/15 22:48:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -319,6 +319,8 @@ typedef struct xl_btree_newroot
  */
 extern bool BuildingBtree;		/* in nbtree.c */
 
+extern void AtEOXact_nbtree(void);
+
 extern Datum btbuild(PG_FUNCTION_ARGS);
 extern Datum btinsert(PG_FUNCTION_ARGS);
 extern Datum btgettuple(PG_FUNCTION_ARGS);
@@ -328,7 +330,7 @@ extern void btmovescan(IndexScanDesc scan, Datum v);
 extern Datum btendscan(PG_FUNCTION_ARGS);
 extern Datum btmarkpos(PG_FUNCTION_ARGS);
 extern Datum btrestrpos(PG_FUNCTION_ARGS);
-extern Datum btdelete(PG_FUNCTION_ARGS);
+extern Datum btbulkdelete(PG_FUNCTION_ARGS);
 
 extern void btree_redo(XLogRecPtr lsn, XLogRecord *record);
 extern void btree_undo(XLogRecPtr lsn, XLogRecord *record);
@@ -346,20 +348,12 @@ extern InsertIndexResult _bt_doinsert(Relation rel, BTItem btitem,
 extern void _bt_metapinit(Relation rel);
 extern Buffer _bt_getroot(Relation rel, int access);
 extern Buffer _bt_getbuf(Relation rel, BlockNumber blkno, int access);
-extern void _bt_relbuf(Relation rel, Buffer buf, int access);
+extern void _bt_relbuf(Relation rel, Buffer buf);
 extern void _bt_wrtbuf(Relation rel, Buffer buf);
 extern void _bt_wrtnorelbuf(Relation rel, Buffer buf);
 extern void _bt_pageinit(Page page, Size size);
 extern void _bt_metaproot(Relation rel, BlockNumber rootbknum, int level);
-extern void _bt_pagedel(Relation rel, ItemPointer tid);
-
-/*
- * prototypes for functions in nbtscan.c
- */
-extern void _bt_regscan(IndexScanDesc scan);
-extern void _bt_dropscan(IndexScanDesc scan);
-extern void _bt_adjscans(Relation rel, ItemPointer tid);
-extern void AtEOXact_nbtree(void);
+extern void _bt_itemdel(Relation rel, Buffer buf, ItemPointer tid);
 
 /*
  * prototypes for functions in nbtsearch.c

src/include/access/rtree.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: rtree.h,v 1.23 2001/05/30 19:53:39 tgl Exp $
+ * $Id: rtree.h,v 1.24 2001/07/15 22:48:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -110,7 +110,7 @@ extern void freestack(RTSTACK *s);
  *		Defined in access/rtree/
  */
 extern Datum rtinsert(PG_FUNCTION_ARGS);
-extern Datum rtdelete(PG_FUNCTION_ARGS);
+extern Datum rtbulkdelete(PG_FUNCTION_ARGS);
 
 extern Datum rtgettuple(PG_FUNCTION_ARGS);
 extern Datum rtbeginscan(PG_FUNCTION_ARGS);
@@ -129,6 +129,7 @@ extern void rtree_desc(char *buf, uint8 xl_info, char *rec);
 /* rtscan.c */
 extern void rtadjscans(Relation r, int op, BlockNumber blkno,
 		   OffsetNumber offnum);
+extern void AtEOXact_rtree(void);
 
 /* rtstrat.c */
 extern RegProcedure RTMapOperator(Relation r, AttrNumber attnum,