Couple additional functions to fix tree at runtime.

Need in one more function to handle "my bits moved..."
case. FixBTree is still FALSE.

src/backend/access/nbtree/nbtinsert.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.78 2001/01/29 07:28:16 vadim Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.79 2001/01/31 01:08:36 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -37,7 +37,9 @@ typedef struct
 extern bool FixBTree;
 
 Buffer _bt_fixroot(Relation rel, Buffer oldrootbuf, bool release);
-static void _bt_fixtree(Relation rel, BlockNumber blkno, BTStack stack);
+static void _bt_fixtree(Relation rel, BlockNumber blkno);
+static BlockNumber _bt_fixlevel(Relation rel, Buffer buf, BlockNumber limit);
+static OffsetNumber _bt_getoff(Page page, BlockNumber blkno);
 
 static Buffer _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf);
 
@@ -512,7 +514,7 @@ _bt_insertonpg(Relation rel,
 						{
 							blkno = lpageop->btpo_parent;
 							_bt_relbuf(rel, buf, BT_WRITE);
-							_bt_fixtree(rel, blkno, NULL);
+							_bt_fixtree(rel, blkno);
 							goto formres;
 						}
 					}
@@ -561,6 +563,10 @@ _bt_insertonpg(Relation rel,
 
 			pbuf = _bt_getstackbuf(rel, stack);
 
+			if (pbuf == InvalidBuffer)
+				elog(ERROR, "_bt_getstackbuf: my bits moved right off the end of the world!"
+					 "\n\tRecreate index %s.", RelationGetRelationName(rel));
+
 			/* Now we can write and unlock the children */
 			_bt_wrtbuf(rel, rbuf);
 			_bt_wrtbuf(rel, buf);
@@ -1172,8 +1178,10 @@ _bt_getstackbuf(Relation rel, BTStack stack)
 		}
 		/* by here, the item we're looking for moved right at least one page */
 		if (P_RIGHTMOST(opaque))
-			elog(FATAL, "_bt_getstackbuf: my bits moved right off the end of the world!"
-				 "\n\tRecreate index %s.", RelationGetRelationName(rel));
+		{
+			_bt_relbuf(rel, buf, BT_WRITE);
+			return(InvalidBuffer);
+		}
 
 		blkno = opaque->btpo_next;
 		_bt_relbuf(rel, buf, BT_WRITE);
@@ -1450,6 +1458,7 @@ _bt_fixroot(Relation rel, Buffer oldrootbuf, bool release)
 
 		/* give up left buffer */
 		_bt_relbuf(rel, leftbuf, BT_WRITE);
+		pfree(btitem);
 		leftbuf = rightbuf;
 		leftpage = rightpage;
 		leftopaque = rightopaque;
@@ -1477,10 +1486,318 @@ _bt_fixroot(Relation rel, Buffer oldrootbuf, bool release)
 	return(rootbuf);
 }
 
+/*
+ * Using blkno of leftmost page on a level inside tree this func
+ * checks/fixes tree from this level up to the root page.
+ */
 static void
-_bt_fixtree(Relation rel, BlockNumber blkno, BTStack stack)
+_bt_fixtree(Relation rel, BlockNumber blkno)
+{
+	Buffer			buf;
+	Page			page;
+	BTPageOpaque	opaque;
+	BlockNumber		pblkno;
+
+	elog(ERROR, "bt_fixtree: unimplemented , yet (need to recreate index)");
+
+	for ( ; ; )
+	{
+		buf = _bt_getbuf(rel, blkno, BT_READ);
+		page = BufferGetPage(buf);
+		opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+		if (! P_LEFTMOST(opaque) || P_ISLEAF(opaque))
+			elog(ERROR, "bt_fixtree: invalid start page (need to recreate index)");
+		pblkno = opaque->btpo_parent;
+
+		/* check/fix entire level */
+		_bt_fixlevel(rel, buf, InvalidBlockNumber);
+
+		/*
+		 * No pins/locks are held here. Re-read start page if its
+		 * btpo_parent pointed to meta page else go up one level.
+		 */
+		if (pblkno == BTREE_METAPAGE)
+		{
+			buf = _bt_getbuf(rel, blkno, BT_WRITE);
+			page = BufferGetPage(buf);
+			opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+			if (P_ISROOT(opaque))
+			{
+				/* Tree is Ok now */
+				_bt_relbuf(rel, buf, BT_WRITE);
+				return;
+			}
+			pblkno = opaque->btpo_parent;
+			/* Call _bt_fixroot() if there is no upper level */
+			if (pblkno == BTREE_METAPAGE)
+			{
+				buf = _bt_fixroot(rel, buf, true);
+				_bt_relbuf(rel, buf, BT_WRITE);
+				return;
+			}
+			/* Have to go up one level */
+			_bt_relbuf(rel, buf, BT_WRITE);
+			blkno = pblkno;
+		}
+	}
+
+}
+
+/*
+ * Check/fix level starting from page in buffer buf up to block
+ * limit on *child* level (or till rightmost child page if limit
+ * is InvalidBlockNumber). Start buffer must be read locked.
+ * No pins/locks are held on exit. Returns block number of last
+ * visited/pointing-to-limit page on *check/fix* level.
+ */
+static BlockNumber
+_bt_fixlevel(Relation rel, Buffer buf, BlockNumber limit)
+{
+	BlockNumber		blkno = BufferGetBlockNumber(buf);
+	BlockNumber		pblkno = blkno;
+	Page			page;
+	BTPageOpaque	opaque;
+	BlockNumber		cblkno[3];
+	OffsetNumber	coff[3];
+	Buffer			cbuf[3];
+	Page			cpage[3];
+	BTPageOpaque	copaque[3];
+	BTItem			btitem;
+	int				cidx, i;
+	bool			goodbye = false;
+	char			tbuf[BLCKSZ];
+
+	page = BufferGetPage(buf);
+	/* copy page to temp storage */
+	memmove(tbuf, page, PageGetPageSize(page));
+	_bt_relbuf(rel, buf, BT_READ);
+
+	page = (Page)tbuf;
+	opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+
+	/* Initialize first child data */
+	coff[0] = P_FIRSTDATAKEY(opaque);
+	if (coff[0] > PageGetMaxOffsetNumber(page))
+		elog(ERROR, "bt_fixlevel: invalid maxoff on start page (need to recreate index)");
+	btitem = (BTItem) PageGetItem(page, PageGetItemId(page, coff[0]));
+	cblkno[0] = ItemPointerGetBlockNumber(&(btitem->bti_itup.t_tid));
+	cbuf[0] = _bt_getbuf(rel, cblkno[0], BT_READ);
+	cpage[0] = BufferGetPage(cbuf[0]);
+	copaque[0] = (BTPageOpaque) PageGetSpecialPointer(cpage[0]);
+	if (P_LEFTMOST(opaque) && ! P_LEFTMOST(copaque[0]))
+		elog(ERROR, "bt_fixtlevel: non-leftmost child page of leftmost parent (need to recreate index)");
+	/* caller should take care and avoid this */
+	if (P_RIGHTMOST(copaque[0]))
+		elog(ERROR, "bt_fixtlevel: invalid start child (need to recreate index)");
+
+	for ( ; ; )
+	{
+		/*
+		 * Read up to 2 more child pages and look for pointers
+		 * to them in *saved* parent page
+		 */
+		coff[1] = coff[2] = InvalidOffsetNumber;
+		for (cidx = 0; cidx < 2; )
+		{
+			cidx++;
+			cblkno[cidx] = (copaque[cidx - 1])->btpo_next;
+			cbuf[cidx] = _bt_getbuf(rel, cblkno[cidx], BT_READ);
+			cpage[cidx] = BufferGetPage(cbuf[cidx]);
+			copaque[cidx] = (BTPageOpaque) PageGetSpecialPointer(cpage[cidx]);
+			coff[cidx] = _bt_getoff(page, cblkno[cidx]);
+
+			/* sanity check */
+			if (coff[cidx] != InvalidOffsetNumber)
+			{
+				for (i = cidx - 1; i >= 0; i--)
+				{
+					if (coff[i] == InvalidOffsetNumber)
+						continue;
+					if (coff[cidx] != coff[i] + 1)
+						elog(ERROR, "bt_fixlevel: invalid item order(1) (need to recreate index)");
+					break;
+				}
+			}
+
+			if (P_RIGHTMOST(copaque[cidx]))
+				break;
+		}
+
+		/*
+		 * Read parent page and insert missed pointers.
+		 */
+		if (coff[1] == InvalidOffsetNumber ||
+			(cidx == 2 && coff[2] == InvalidOffsetNumber))
+		{
+			Buffer			newbuf;
+			Page			newpage;
+			BTPageOpaque	newopaque;
+			BTItem			ritem;
+			Size			itemsz;
+			OffsetNumber	newitemoff;
+			BlockNumber		parblk[3];
+			BTStackData		stack;
+
+			stack.bts_parent = NULL;
+			stack.bts_blkno = pblkno;
+			stack.bts_offset = InvalidOffsetNumber;
+			ItemPointerSet(&(stack.bts_btitem.bti_itup.t_tid),
+							cblkno[0], P_HIKEY);
+
+			buf = _bt_getstackbuf(rel, &stack);
+			if (buf == InvalidBuffer)
+				elog(ERROR, "bt_fixlevel: pointer disappeared (need to recreate index)");
+
+			page = BufferGetPage(buf);
+			opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+			coff[0] = stack.bts_offset;
+			pblkno = BufferGetBlockNumber(buf);
+			parblk[0] = pblkno;
+			if (cblkno[0] == limit)
+				blkno = pblkno;		/* where we have seen pointer to limit */
+
+			/* Check/insert missed pointers */
+			for (i = 1; i <= cidx; i++)
+			{
+				coff[i] = _bt_getoff(page, cblkno[i]);
+
+				/* sanity check */
+				parblk[i] = BufferGetBlockNumber(buf);
+				if (coff[i] != InvalidOffsetNumber)
+				{
+					if (parblk[i] == parblk[i - 1] &&
+								coff[i] != coff[i - 1] + 1)
+						elog(ERROR, "bt_fixlevel: invalid item order(2) (need to recreate index)");
+					if (cblkno[i] == limit)
+						blkno = parblk[i];
+					continue;
+				}
+				/* Have to check next page ? */
+				if ((! P_RIGHTMOST(opaque)) &&
+					coff[i - 1] == PageGetMaxOffsetNumber(page))	/* yes */
+				{
+					newbuf = _bt_getbuf(rel, opaque->btpo_next, BT_WRITE);
+					newpage = BufferGetPage(newbuf);
+					newopaque = (BTPageOpaque) PageGetSpecialPointer(newpage);
+					coff[i] = _bt_getoff(newpage, cblkno[i]);
+					if (coff[i] != InvalidOffsetNumber)	/* found ! */
+					{
+						if (coff[i] != P_FIRSTDATAKEY(newopaque))
+							elog(ERROR, "bt_fixlevel: invalid item order(3) (need to recreate index)");
+						_bt_relbuf(rel, buf, BT_WRITE);
+						buf = newbuf;
+						page = newpage;
+						opaque = newopaque;
+						pblkno = BufferGetBlockNumber(buf);
+						parblk[i] = pblkno;
+						if (cblkno[i] == limit)
+							blkno = pblkno;
+						continue;
+					}
+					/* unfound - need to insert on current page */
+					_bt_relbuf(rel, newbuf, BT_WRITE);
+				}
+				/* insert pointer */
+				ritem = (BTItem) PageGetItem(cpage[i - 1],
+									PageGetItemId(cpage[i - 1], P_HIKEY));
+				btitem = _bt_formitem(&(ritem->bti_itup));
+				ItemPointerSet(&(btitem->bti_itup.t_tid), cblkno[i], P_HIKEY);
+				itemsz = IndexTupleDSize(btitem->bti_itup)
+					+ (sizeof(BTItemData) - sizeof(IndexTupleData));
+				itemsz = MAXALIGN(itemsz);
+
+				newitemoff = coff[i - 1] + 1;
+
+				if (PageGetFreeSpace(page) < itemsz)
+				{
+					OffsetNumber	firstright;
+					OffsetNumber	itup_off;
+					BlockNumber		itup_blkno;
+					bool			newitemonleft;
+
+					firstright = _bt_findsplitloc(rel, page,
+									newitemoff, itemsz, &newitemonleft);
+					newbuf = _bt_split(rel, buf, firstright,
+								newitemoff, itemsz, btitem, newitemonleft,
+								&itup_off, &itup_blkno);
+					/* what buffer we need in ? */
+					if (newitemonleft)
+						_bt_relbuf(rel, newbuf, BT_WRITE);
+					else
+					{
+						_bt_relbuf(rel, buf, BT_WRITE);
+						buf = newbuf;
+						page = BufferGetPage(buf);
+						opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+					}
+					pblkno = BufferGetBlockNumber(buf);
+					coff[i] = itup_off;
+				}
+				else
+				{
+					_bt_insertuple(rel, buf, itemsz, btitem, newitemoff);
+					coff[i] = newitemoff;
+				}
+
+				pfree(btitem);
+				parblk[i] = pblkno;
+				if (cblkno[i] == limit)
+					blkno = pblkno;
+			}
+
+			/* copy page with pointer to cblkno[cidx] to temp storage */
+			memmove(tbuf, page, PageGetPageSize(page));
+			_bt_relbuf(rel, buf, BT_WRITE);
+			page = (Page)tbuf;
+			opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+			if (limit == InvalidBlockNumber)
+				blkno = pblkno;		/* last visited page */
+		}
+
+		/* Continue if current check/fix level page is rightmost */
+		if (P_RIGHTMOST(opaque))
+			goodbye = false;
+
+		/* Pointers to child pages are Ok - right end of child level ? */
+		_bt_relbuf(rel, cbuf[0], BT_READ);
+		_bt_relbuf(rel, cbuf[1], BT_READ);
+		if (cidx == 1 ||
+			(cidx == 2 && (P_RIGHTMOST(copaque[2]) || goodbye)))
+		{
+			if (cidx == 2)
+				_bt_relbuf(rel, cbuf[2], BT_READ);
+			return(blkno);
+		}
+		if (cblkno[0] == limit || cblkno[1] == limit)
+			goodbye = true;
+		cblkno[0] = cblkno[2];
+		cbuf[0] = cbuf[2];
+		cpage[0] = cpage[2];
+		copaque[0] = copaque[2];
+		coff[0] = coff[2];
+	}
+}
+
+static OffsetNumber
+_bt_getoff(Page page, BlockNumber blkno)
 {
-	elog(ERROR, "bt_fixtree: unimplemented , yet");
+	BTPageOpaque	opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+	OffsetNumber	maxoff = PageGetMaxOffsetNumber(page);
+	OffsetNumber	offnum = P_FIRSTDATAKEY(opaque);
+	BlockNumber		curblkno;
+	ItemId			itemid;
+	BTItem			item;
+
+	for ( ; offnum <= maxoff; offnum++)
+	{
+		itemid = PageGetItemId(page, offnum);
+		item = (BTItem) PageGetItem(page, itemid);
+		curblkno = ItemPointerGetBlockNumber(&(item->bti_itup.t_tid));
+		if (curblkno == blkno)
+			return(offnum);
+	}
+
+	return(InvalidOffsetNumber);
 }
 
 /*