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been replaced by a "bulk delete" routine in which the indexscan is inside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.

1 files changed, 20 insertions, 21 deletions

diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
index 67e1407b22b..376274c5621 100644
--- a/src/backend/access/nbtree/nbtpage.c
+++ b/src/backend/access/nbtree/nbtpage.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.52 2001/06/27 23:31:38 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtpage.c,v 1.53 2001/07/15 22:48:16 tgl Exp $
  *
  *	NOTES
  *	   Postgres btree pages look like ordinary relation pages.	The opaque
@@ -138,7 +138,7 @@ _bt_getroot(Relation rel, int access)
 		/* If access = BT_READ, caller doesn't want us to create root yet */
 		if (access == BT_READ)
 		{
-			_bt_relbuf(rel, metabuf, BT_READ);
+			_bt_relbuf(rel, metabuf);
 			return InvalidBuffer;
 		}
 
@@ -215,14 +215,14 @@ _bt_getroot(Relation rel, int access)
 			 * guarantee no deadlocks, we have to release the metadata
 			 * page and start all over again.
 			 */
-			_bt_relbuf(rel, metabuf, BT_WRITE);
+			_bt_relbuf(rel, metabuf);
 			return _bt_getroot(rel, access);
 		}
 	}
 	else
 	{
 		rootblkno = metad->btm_root;
-		_bt_relbuf(rel, metabuf, BT_READ);		/* done with the meta page */
+		_bt_relbuf(rel, metabuf);		/* done with the meta page */
 
 		rootbuf = _bt_getbuf(rel, rootblkno, BT_READ);
 	}
@@ -270,8 +270,8 @@ _bt_getroot(Relation rel, int access)
 					goto check_parent;
 				}
 				else
-/* someone else already fixed root */
 				{
+					/* someone else already fixed root */
 					LockBuffer(rootbuf, BUFFER_LOCK_UNLOCK);
 					LockBuffer(rootbuf, BT_READ);
 				}
@@ -283,7 +283,7 @@ _bt_getroot(Relation rel, int access)
 			 * chance that parent is root page.
 			 */
 			newrootbuf = _bt_getbuf(rel, rootopaque->btpo_parent, BT_READ);
-			_bt_relbuf(rel, rootbuf, BT_READ);
+			_bt_relbuf(rel, rootbuf);
 			rootbuf = newrootbuf;
 			rootpage = BufferGetPage(rootbuf);
 			rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpage);
@@ -293,7 +293,7 @@ _bt_getroot(Relation rel, int access)
 		}
 
 		/* try again */
-		_bt_relbuf(rel, rootbuf, BT_READ);
+		_bt_relbuf(rel, rootbuf);
 		return _bt_getroot(rel, access);
 	}
 
@@ -350,10 +350,12 @@ _bt_getbuf(Relation rel, BlockNumber blkno, int access)
 /*
  *	_bt_relbuf() -- release a locked buffer.
  *
- * Lock and pin (refcount) are both dropped.
+ * Lock and pin (refcount) are both dropped.  Note that either read or
+ * write lock can be dropped this way, but if we modified the buffer,
+ * this is NOT the right way to release a write lock.
  */
 void
-_bt_relbuf(Relation rel, Buffer buf, int access)
+_bt_relbuf(Relation rel, Buffer buf)
 {
 	LockBuffer(buf, BUFFER_LOCK_UNLOCK);
 	ReleaseBuffer(buf);
@@ -449,24 +451,23 @@ _bt_metaproot(Relation rel, BlockNumber rootbknum, int level)
 }
 
 /*
- * Delete an item from a btree.  It had better be a leaf item...
+ * Delete an item from a btree page.
+ *
+ * This routine assumes that the caller has pinned and locked the buffer,
+ * and will write the buffer afterwards.
  */
 void
-_bt_pagedel(Relation rel, ItemPointer tid)
+_bt_itemdel(Relation rel, Buffer buf, ItemPointer tid)
 {
-	Buffer		buf;
-	Page		page;
-	BlockNumber blkno;
+	Page		page = BufferGetPage(buf);
 	OffsetNumber offno;
 
-	blkno = ItemPointerGetBlockNumber(tid);
 	offno = ItemPointerGetOffsetNumber(tid);
 
-	buf = _bt_getbuf(rel, blkno, BT_WRITE);
-	page = BufferGetPage(buf);
-
 	START_CRIT_SECTION();
+
 	PageIndexTupleDelete(page, offno);
+
 	/* XLOG stuff */
 	{
 		xl_btree_delete xlrec;
@@ -490,8 +491,6 @@ _bt_pagedel(Relation rel, ItemPointer tid)
 		PageSetLSN(page, recptr);
 		PageSetSUI(page, ThisStartUpID);
 	}
-	END_CRIT_SECTION();
 
-	/* write the buffer and release the lock */
-	_bt_wrtbuf(rel, buf);
+	END_CRIT_SECTION();
 }