A Conversation with Margo Seltzer and Mike Olson

Kirk McKusick sat down with Margo Seltzer and Mike Olson to discuss the history of Berkeley DB, for which they won the ACM Software System Award in 2021. Kirk McKusick has spent his career as a BSD and FreeBSD developer. Margo Seltzer has spent her career as a professor of computer science and as an entrepreneur of database software companies. Mike Olson started his career as a software developer and later started and managed several open-source software companies. Berkeley DB is a production-quality, scalable, NoSQL, Open Source platform for embedded transactional data management.

A Study on Image Search System using Semantics Based on Smartphone

Image semantic retrieval has been a crux to bridge "semantic gap" between the simple visual features and the abundant semantics delivered by a image. Effective image retrieval using semantics is one of the major challenges in image retrieval. We suggest a semantic retrieval and clustering method of image using image annotation user interface. And also design and implement a image semantic search management system that facilitates image management and semantic retrieval, which fully relies on the MPEG-7 standard as information base, and using a native XML database, which is Berkeley DB XML.

A flash-aware buffering scheme with the on-the-fly redo for efficient data management in flash storage

Thanks to remarkably fast random reads and rapidly decreasing prices per bit, flash storage has been regarded as a promising alternative to traditional hard disk drives (HDDs). Although flash storage has many distinguished hardware features, it still suffers from the poor I/O performance in the case of update operations. Due to the absence of in-place updates, differently from HDDs, flash storage needs to modify data through out-of-place updates. For this reason, it is required to continuously renew the mapping information between a logical page address and its new physical address, invalidating its old physical address. When the invalidated pages swallow most of free space in flash storage, the actions of garbage reclamation are needed. Since the actions of garbage reclamation are very costly, it is crucial to reduce the number of update operations for the use of flash storage in enterprise-scale database systems. In this light, we propose a new buffering scheme that evicts dirty pages without writing them to storage, thereby reducing the amount of update operations considerably. That is, our buffering scheme enables the flushing-less evictions of dirty pages. To correctly read a page undergoing its flushing-less eviction, we propose a new on-the-fly redo mechanism that enables restoring the lost updates of the page in normal database processing. For fast execution of the on-the-fly redo, we maintain memory-resident log data of a reasonable size. To show the performance advantages of the proposed scheme, we performed extensive experiments based on the TPC-C benchmark, by running them on the open-sourced Berkeley DB equipped with/without our scheme. The results show that our scheme yields a much better performance by reducing the amount of page updates significantly.

Digital library technology in J-ISIS: concept, implementation and comparison with GSDL

Purpose – Although the new J-ISIS software from UNESCO, based on Berkeley DB and Lucene technology, complies with some of the technical requirements as seen necessary for digital library applications, an easy way of building collections so far was not available. The purpose of this paper is to give a report on some necessary DL technological requirements, such as the capability to deal with any metadata structure and alphabets and full-text indexing of documents of any length, and how J-ISIS can deal with these, as well as on the production of the DL interface for digital library applications based on Tika technology. Design/methodology/approach – A brief comparison is made with a well-established DL software, i.e. Greenstone Digital Library, regarding the concepts and performance. Findings – While using a quite different architecture and approach, the test shows that J-ISIS can process the documents faster and with more economical storage efficiency, inviting UNESCO to invest more into it in order to allow incorporation of some more advanced features like Greenstone's capability to process intra-document segments and images, but also to allow for new exciting features for digital libraries such as interactivity. Research limitations/implications – The research is based on the J-ISIS prototype implementation of digital library technology and could only be tested on a limited set of documents. Practical implications – Librarians interested in building digital library collections, esp. when doing this integrated with their library systems and catalogs, have a viable new option now within the FOSS-market. Originality/value – This is the first description on J-ISIS for digital libraries.

Application of Improved B+-Trees Algorithm in Embedded Database

B+-trees algorithm is a high efficient and common-used data organization algorithm in database system. But B+-trees algorithm has a disadvantage of low storage utilization. This disadvantage has a bad effect especially on embedded database systems, which have limit storage. To overcome this drawback, this paper presents an improved B+-trees algorithm, and applies it to an embedded database-Berkeley DB. Experimental results show that the improved B+-trees algorithm can attain higher storage utilization at the expense of more execution time than the conventional B+-trees algorithm.

Study and Optimization of Database on Android Platform

Due to the poor database performance situation on Android operating system, put forward a methods of database access performance optimization. The paper first analyze the Android database access principle, architecture of SQLite and Berkeley DB, and methods of Berkeley DB in concurrent access, then put forward a method of porting Berkeley DB to Android to replace SQLite to enhance the database access performance. Finally a series of practical benchmark results shows that the porting brings performance improvement effect.