diff options
Diffstat (limited to 'src/backend/access/nbtree/nbtinsert.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtinsert.c | 147 |
1 files changed, 102 insertions, 45 deletions
diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c index 63e06f8e1e3..c1cedd33bda 100644 --- a/src/backend/access/nbtree/nbtinsert.c +++ b/src/backend/access/nbtree/nbtinsert.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.6 1996/11/05 10:35:29 scrappy Exp $ + * $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.7 1996/11/13 20:47:11 scrappy Exp $ * *------------------------------------------------------------------------- */ @@ -31,7 +31,10 @@ static OffsetNumber _bt_findsplitloc(Relation rel, Page page, OffsetNumber start static void _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf); static OffsetNumber _bt_pgaddtup(Relation rel, Buffer buf, int keysz, ScanKey itup_scankey, Size itemsize, BTItem btitem, BTItem afteritem); static bool _bt_goesonpg(Relation rel, Buffer buf, Size keysz, ScanKey scankey, BTItem afteritem); + +#if 0 static void _bt_updateitem(Relation rel, Size keysz, Buffer buf, Oid bti_oid, BTItem newItem); +#endif /* * _bt_doinsert() -- Handle insertion of a single btitem in the tree. @@ -41,7 +44,7 @@ static void _bt_updateitem(Relation rel, Size keysz, Buffer buf, Oid bti_oid, BT * (xid, seqno) pair. */ InsertIndexResult -_bt_doinsert(Relation rel, BTItem btitem) +_bt_doinsert(Relation rel, BTItem btitem, bool index_is_unique, bool is_update) { ScanKey itup_scankey; IndexTuple itup; @@ -59,6 +62,31 @@ _bt_doinsert(Relation rel, BTItem btitem) /* find the page containing this key */ stack = _bt_search(rel, natts, itup_scankey, &buf); + + /* if we're not allowing duplicates, make sure the key isn't */ + /* already in the node */ + if(index_is_unique && !is_update) { + OffsetNumber offset; + TupleDesc itupdesc; + Page page; + + itupdesc = RelationGetTupleDescriptor(rel); + page = BufferGetPage(buf); + + offset = _bt_binsrch(rel, buf, natts, itup_scankey, BT_DESCENT); + + /* make sure the offset we're given points to an actual */ + /* key on the page before trying to compare it */ + if(!PageIsEmpty(page) && + offset <= PageGetMaxOffsetNumber(page)) { + if(!_bt_compare(rel, itupdesc, page, + natts, itup_scankey, offset)) { + /* it is a duplicate */ + elog(WARN, "Cannot insert a duplicate key into a unique index."); + } + } + } + blkno = BufferGetBlockNumber(buf); /* trade in our read lock for a write lock */ @@ -137,6 +165,10 @@ _bt_insertonpg(Relation rel, InsertIndexResult newres; BTItem new_item = (BTItem) NULL; BTItem lowLeftItem; + OffsetNumber leftmost_offset; + Page ppage; + BTPageOpaque ppageop; + BlockNumber bknum; page = BufferGetPage(buf); itemsz = IndexTupleDSize(btitem->bti_itup) @@ -236,14 +268,67 @@ _bt_insertonpg(Relation rel, lowLeftItem = (BTItem) PageGetItem(page, PageGetItemId(page, P_FIRSTKEY)); - /* page must have right pointer after split */ - _bt_updateitem(rel, keysz, pbuf, stack->bts_btitem->bti_oid, - lowLeftItem); + + /* this method does not work--_bt_updateitem tries to */ + /* overwrite an entry with another entry that might be */ + /* bigger. if lowLeftItem is bigger, it corrupts the */ + /* parent page. instead, we have to delete the original */ + /* leftmost item from the parent, and insert the new one */ + /* with a regular _bt_insertonpg (it could cause a split */ + /* because it's bigger than what was there before). */ + /* --djm 8/21/96 */ + + /* _bt_updateitem(rel, keysz, pbuf, stack->bts_btitem->bti_oid, + lowLeftItem); */ + + /* get the parent page */ + ppage = BufferGetPage(pbuf); + ppageop = (BTPageOpaque) PageGetSpecialPointer(ppage); + + /* figure out which key is leftmost (if the parent page */ + /* is rightmost, too, it must be the root) */ + if(P_RIGHTMOST(ppageop)) { + leftmost_offset = P_HIKEY; + } else { + leftmost_offset = P_FIRSTKEY; } + PageIndexTupleDelete(ppage, leftmost_offset); + + /* don't write anything out yet--we still have the write */ + /* lock, and now we call another _bt_insertonpg to */ + /* insert the correct leftmost key */ + + /* make a new leftmost item, using the tuple data from */ + /* lowLeftItem. point it to the left child. */ + /* update it on the stack at the same time. */ + bknum = BufferGetBlockNumber(buf); + pfree(stack->bts_btitem); + stack->bts_btitem = _bt_formitem(&(lowLeftItem->bti_itup)); + ItemPointerSet(&(stack->bts_btitem->bti_itup.t_tid), + bknum, P_HIKEY); + + /* unlock the children before doing this */ + _bt_relbuf(rel, buf, BT_WRITE); + _bt_relbuf(rel, rbuf, BT_WRITE); + + /* a regular _bt_binsrch should find the right place to */ + /* put the new entry, since it should be lower than any */ + /* other key on the page, therefore set afteritem to NULL */ + newskey = _bt_mkscankey(rel, &(stack->bts_btitem->bti_itup)); + newres = _bt_insertonpg(rel, pbuf, stack->bts_parent, + keysz, newskey, stack->bts_btitem, + NULL); + + pfree(newres); + pfree(newskey); - /* don't need the children anymore */ + /* we have now lost our lock on the parent buffer, and */ + /* need to get it back. */ + pbuf = _bt_getstackbuf(rel, stack, BT_WRITE); + } else { _bt_relbuf(rel, buf, BT_WRITE); _bt_relbuf(rel, rbuf, BT_WRITE); + } newskey = _bt_mkscankey(rel, &(new_item->bti_itup)); newres = _bt_insertonpg(rel, pbuf, stack->bts_parent, @@ -787,6 +872,8 @@ _bt_itemcmp(Relation rel, return (true); } +#if 0 +/* gone since updating in place doesn't work in general --djm 11/13/96 */ /* * _bt_updateitem() -- updates the key of the item identified by the * oid with the key of newItem (done in place if @@ -804,9 +891,9 @@ _bt_updateitem(Relation rel, OffsetNumber maxoff; OffsetNumber i; ItemPointerData itemPtrData; - BTItem item, itemCopy; + BTItem item; IndexTuple oldIndexTuple, newIndexTuple; - int newSize, oldSize, first; + int first; page = BufferGetPage(buf); maxoff = PageGetMaxOffsetNumber(page); @@ -825,48 +912,18 @@ _bt_updateitem(Relation rel, elog(FATAL, "_bt_getstackbuf was lying!!"); } + if(IndexTupleDSize(newItem->bti_itup) > + IndexTupleDSize(item->bti_itup)) { + elog(NOTICE, "trying to overwrite a smaller value with a bigger one in _bt_updateitem"); + elog(WARN, "this is not good."); + } + oldIndexTuple = &(item->bti_itup); newIndexTuple = &(newItem->bti_itup); - oldSize = DOUBLEALIGN(IndexTupleSize(oldIndexTuple)); - newSize = DOUBLEALIGN(IndexTupleSize(newIndexTuple)); -#ifdef NBTINSERT_PATCH_DEBUG - printf("_bt_updateitem: newSize=%d, oldSize=%d\n", newSize, oldSize); -#endif - /* - * If new and old item have the same size do the update in place - * and return. - */ - if (oldSize == newSize) { /* keep the original item pointer */ ItemPointerCopy(&(oldIndexTuple->t_tid), &itemPtrData); CopyIndexTuple(newIndexTuple, &oldIndexTuple); ItemPointerCopy(&itemPtrData, &(oldIndexTuple->t_tid)); - return; - } - - /* - * If new and old items have different size the update in place - * is not possible. In this case the old item is deleted and the - * new one is inserted. - * The new insertion should be done using _bt_insertonpg which - * would also takes care of the page splitting if needed, but - * unfortunately it doesn't work, so PageAddItem is used instead. - * There is the possibility that there is not enough space in the - * page and the item is not inserted. - */ - itemCopy = palloc(newSize); - memmove((char *) itemCopy, (char *) newItem, newSize); - itemCopy->bti_oid = item->bti_oid; - newIndexTuple = &(itemCopy->bti_itup); - ItemPointerCopy(&(oldIndexTuple->t_tid), &(newIndexTuple->t_tid)); - - /* - * Get the offset number of the item then delete it and insert - * the new item in the same place. - */ - i = OffsetNumberPrev(i); - PageIndexTupleDelete(page, i); - PageAddItem(page, (Item) itemCopy, newSize, i, LP_USED); - pfree(itemCopy); } +#endif |