Experimenting with Temporal Relational Databases

In this paper we describe an implementation of a temporal relational database management system based on attribute timestamping. The algebraic language of the system includes relational algebra operators, restructuring operators and temporal operators. We then use this system to carry out experiments on the performance of different types of temporal databases: databases using attribute timestamping, databases using tuple timestamping where relations are in temporal normal form and databases using tuple timestamping where a single relation is used. We run sample queries against these types of temporal databases and measure the processing time of these queries. This study verifies that the major performance trade off between different types of temporal databases is between the restructuring (unpack) operation needed in temporal databases using attribute timestamping and the join operation needed in temporal databases using tuple timestamping. Furthermore, the experiments show that keepin..

Temporal join processing with hilbert curve space mapping

Management of data with a time dimension increases the overhead of storage and query processing in large database applications especially with the join operation, which is a commonly used and expensive relational operator. The join evaluation is difficult because temporal data are intrinsically multidimensional. The problem is harder since tuples with longer life spans tend to overlap a greater number of joining tuples thus; they are likely to be accessed more often. The proposed index-based Hilbert-Temporal Join (Hilbert-TJ) join algorithm maps temporal data into Hilbert curve space that is inherently clustered, thus allowing for fast retrieval and storage. An evaluation and comparison study of the proposed Hilbert-TJ algorithm determined the relative performance with respect to a nested-loop join, a sort-merge, and a partition-based join algorithm that use a multiversion B+ tree (MVBT) index. The metrics include the processing time (disk I/O time plus CPU time) and index storage size. Under the given conditions, the expected outcome was that by reducing index redundancy better performance was achieved. Additionally, the Hilbert-TJ algorithm offers support to both valid-time and transaction-time data

The effects of aflatoxin residues on nutritional contents in ground red chili peppers (Capsicum annuum)

WOS: 000435278400151