/// <exception cref="System.IO.IOException"></exception> public override void Open() { _mappingDb = DefragmentServicesImpl.FreshTempFile(_fileName, 1); _idTree = (_treeSpec == null ? new BTree(Trans(), 0, new MappedIDPairHandler()) : new BTree(Trans(), 0, new MappedIDPairHandler(), _treeSpec.NodeSize())); _slotTree = (_treeSpec == null ? new BTree(Trans(), 0, new BTreeIdSystem.IdSlotMappingHandler ()) : new BTree(Trans(), 0, new BTreeIdSystem.IdSlotMappingHandler(), _treeSpec. NodeSize())); }