BPlusTreeParams params = new BPlusTreeParams(order, factory) ;
if ( params.getCalcBlockSize() > blockSize )
throw new TDBException("Calculated block size is greater than required size") ;
BlockMgr blkMgrNodes = createBlockMgr(fileset, Names.bptExtTree, blockSize) ;
BlockMgr blkMgrRecords = createBlockMgr(fileset, Names.bptExtRecords, blockSize) ;
return BPlusTree.create(params, blkMgrNodes, blkMgrRecords) ;
}