DWORM: A Novel Algorithm To Maintain Large Itemsets in Deleted Items and/or Transactions Databases Without Re-Mining


Transactional databases can be updated by three cases; the addition of new transactions, the deletion of set of transactions, andor increasing or decreasing of the support of the itemsets. The update process affects the previously mined itemsets, some of the large items will be small and vice versa. Therefore the updated database should be re-mined to discover the changes in the hidden itemsets. There are many algorithms to avoid the re-mining process in the case of updating a database by addition and there is one algorithm in case of changing the value of the support. But there is no actual algorithm to avoid the re-mining in the case of deletion. This research presents a novel algorithm to manipulate this case. The proposed algorithm manipulates the three possibilities of the deletion that are deletion of one or more items from a transaction or set of transactions, deletion of a set of transactions, and deletion of items from transactions and deletion of set of transactions at the same time. The experimental result shows that the updating algorithm outperforms the re-mining process in considerable amount of execution time.