Major overhaul of btree index code. Eliminate special BTP_CHAIN logic for

duplicate keys by letting search go to the left rather than right when an
equal key is seen at an upper tree level.  Fix poor choice of page split
point (leading to insertion failures) that was forced by chaining logic.
Don't store leftmost key in non-leaf pages, since it's not necessary.
Don't create root page until something is first stored in the index, so an
unused index is now 8K not 16K.  (Doesn't seem to be as easy to get rid of
the metadata page, unfortunately.)  Massive cleanup of unreadable code,
fix poor, obsolete, and just plain wrong documentation and comments.
See src/backend/access/nbtree/README for the gory details.

1 files changed, 6 insertions, 48 deletions

diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 5853267670..aabdf80900 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.37 2000/05/30 04:24:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.38 2000/07/21 06:42:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -20,16 +20,13 @@
 #include "access/nbtree.h"
 #include "executor/execdebug.h"
 
-extern int	NIndexTupleProcessed;
-
 
 /*
  * _bt_mkscankey
  *		Build a scan key that contains comparison data from itup
  *		as well as comparator routines appropriate to the key datatypes.
  *
- *		The result is intended for use with _bt_skeycmp() or _bt_compare(),
- *		although it could be used with _bt_itemcmp() or _bt_tuplecompare().
+ *		The result is intended for use with _bt_compare().
  */
 ScanKey
 _bt_mkscankey(Relation rel, IndexTuple itup)
@@ -68,8 +65,9 @@ _bt_mkscankey(Relation rel, IndexTuple itup)
  *		Build a scan key that contains comparator routines appropriate to
  *		the key datatypes, but no comparison data.
  *
- *		The result can be used with _bt_itemcmp() or _bt_tuplecompare(),
- *		but not with _bt_skeycmp() or _bt_compare().
+ *		The result cannot be used with _bt_compare().  Currently this
+ *		routine is only called by utils/sort/tuplesort.c, which has its
+ *		own comparison routine.
  */
 ScanKey
 _bt_mkscankey_nodata(Relation rel)
@@ -114,7 +112,6 @@ _bt_freestack(BTStack stack)
 	{
 		ostack = stack;
 		stack = stack->bts_parent;
-		pfree(ostack->bts_btitem);
 		pfree(ostack);
 	}
 }
@@ -331,55 +328,16 @@ _bt_formitem(IndexTuple itup)
 	Size		tuplen;
 	extern Oid	newoid();
 
-	/*
-	 * see comments in btbuild
-	 *
-	 * if (itup->t_info & INDEX_NULL_MASK) elog(ERROR, "btree indices cannot
-	 * include null keys");
-	 */
-
 	/* make a copy of the index tuple with room for the sequence number */
 	tuplen = IndexTupleSize(itup);
 	nbytes_btitem = tuplen + (sizeof(BTItemData) - sizeof(IndexTupleData));
 
 	btitem = (BTItem) palloc(nbytes_btitem);
-	memmove((char *) &(btitem->bti_itup), (char *) itup, tuplen);
+	memcpy((char *) &(btitem->bti_itup), (char *) itup, tuplen);
 
 	return btitem;
 }
 
-#ifdef NOT_USED
-bool
-_bt_checkqual(IndexScanDesc scan, IndexTuple itup)
-{
-	BTScanOpaque so;
-
-	so = (BTScanOpaque) scan->opaque;
-	if (so->numberOfKeys > 0)
-		return (index_keytest(itup, RelationGetDescr(scan->relation),
-							  so->numberOfKeys, so->keyData));
-	else
-		return true;
-}
-
-#endif
-
-#ifdef NOT_USED
-bool
-_bt_checkforkeys(IndexScanDesc scan, IndexTuple itup, Size keysz)
-{
-	BTScanOpaque so;
-
-	so = (BTScanOpaque) scan->opaque;
-	if (keysz > 0 && so->numberOfKeys >= keysz)
-		return (index_keytest(itup, RelationGetDescr(scan->relation),
-							  keysz, so->keyData));
-	else
-		return true;
-}
-
-#endif
-
 bool
 _bt_checkkeys(IndexScanDesc scan, IndexTuple tuple, Size *keysok)
 {