Rebuilding an index is an essential step for database recovery. Fast recovery of the index is a necessary condition for fast database recovery. The B+-Tree is the most popular index structure in database systems. In this paper, we present a fast B+-Tree rebuilding algorithm called Max-PL. The main idea of Max-PL is that at first it constructs a B+-Tree index structure using the pre-stored max keys of the leaf nodes, and then inserts the keys and data pointers into the index. The algorithm employs a pipelining mechanism for reading the data records and inserting the keys into the index. It also exploits parallelisms in several phases to boost the overall performance. We analyze the time complexity and space requirement of the algorithm, and perform the experimental study to compare its performance to other B+-Trees rebuilding algorithms; Sequential Insertion and Batch-Construction. The results show that our algorithm runs on average at least 670% faster than Sequential Insertion and 200% faster than Batch-Construction.

The Web is a collection of multimedia documents in the form of HTML pages connected through hyperlinks. Unlike most search engines, which focus on information retrieval based on keywords, WebDB aims at supporting database-like comprehensive query functionalities as well navigation, and document generation functionalities with customizability. To support hypermedia database functionalities, we augment the traditional concepts of tables in relational databases and classes in object-oriented databases with notions of document formats and navigation. We design WQL (Web Query Language) as an HTML document manipulation language. WQL language statements contain two parts: SELECT. . . FROM. . . WHERE clauses for specifying retrieval of data contents from hypermedia databases and CREATE. . . AS. . . clauses for specifying the output HTML format and navigation of the query results. This paper presents the architecture of WebDB and its functionalities. The extension to SQL for hypermedia document manipulation, query, and navigation and implementation on NEC PERCIO OODBMS are described in detail.