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As NoSQL grows in popularity, many organizations are attempting to migrate their databases from RDBMS to NoSQL. Because NoSQL is very different from RDBMS, such migration is a challenging issue. For example, NoSQL does not support join operations or transactions. We propose a novel solution for database migration from RDBMS to document-oriented NoSQL, which is the most widely used type of NoSQL. Our method not only avoids join operations with a marginal increase in the database size, but also supports atomicity using the notions of column-level denormalization and atomic aggregates. Column-level denormalization duplicates only columns that are accessed in non-primary-foreign-key-join predicates. Atomic aggregates combine tables that are modified within the same transaction into a unit of atomic updates called an aggregate. Experimental results using TPC-H and MongoDB show that our method improves the query performance by up to 2.2 times using 1.5 times more space compared with a baseline method that uses the relational schema as it is. Compared with the state-of-the-art method, which duplicates whole tables to avoid join operations, our method improves the query performance by up to 2.0 times with 2.8 times less space. [ABSTRACT FROM AUTHOR]

These days, huge amounts of data are created by not only humans but also the Internet of Things (loT). As databases increase in size, their buffer pool is becoming more crucial to the overall performance. Buffer flushing, i.e., writing dirty pages, is a key factor in buffer pool management. Tuning the buffer-flushing activity in a real system is often difficult because it depends on the workload and system configuration. It is usually done through trial and error. In this paper, we propose a self-tuning algorithm for automatically controlling the buffer-flushing activity. Our algorithm not only avoids synchronous writes, which block other operations, but also preserves the effectiveness of the buffer pool. Experimental results using TPC-C and TPC-H show that our algorithm gives up to a 2.1-fold higher throughput compared with the original buffer-flushing algorithm of MySQL and 1.5-fold compared with that of Percona Server, which is a variant of MySQL. [ABSTRACT FROM AUTHOR]

In the present study, methylated silk sericin (MeSS) was prepared and a bead-type drug delivery carrier was formulated for the potent treatment of Helicobacter pylori infection. Sericin was reacted with methanol in the presence of hydrochloric acid as a catalyst under mild conditions to form an ester bond between the carboxyl group of sericin and the hydroxyl group of methanol. The methylation of silk sericin was confirmed by Fourier transform infrared spectroscopy (FTIR) and point of zero charge (pHpzc) studies. The formulated MeSS beads swelled more under acidic conditions, which is below the pHpzc of the MeSS. The release behavior of the model drug from the MeSS beads in the medium was extremely phi-sensitive. These results suggest that the formulated MeSS beads have the potential to be an effective antimicrobial agent carrier for the treatment of H. pylori infection. [ABSTRACT FROM AUTHOR]