Temporal Data and Relational Theory

Two recent trends—the plummeting cost of storage and the widespread adoption of data warehouse technology—have led to an increasing interest in temporal databases. Indeed, the idea of maintaining and processing historical data has become not just a goal but a reality for many organizations. As a consequence, the ability to deal properly with the time dimension in databases has become an increasingly important practical problem. And today’s mainstream DBMS products are (at last, some might say) beginning to include features that are specifically designed to help with this important requirement—though it has to be said too that the support currently found in those products falls a long way short of the theoretical ideal.

This video seminar describes and explains that theoretical ideal—which, interestingly, is 100% consistent with the classical relational model—in depth. It also describes the new temporal support to be found in the SQL standard (“SQL:2011”), as well as in certain of today’s major SQL products.

The seminar overall falls into four major parts:

• Part I consists of a quick review of relevant aspects of the relational model.
• Part II, “Laying the Foundations,” explains some of the basic problems of temporal databases (some of which are far from obvious, incidentally) and lays the groundwork for solving those problems.
• Part III, “Building on the Foundations,” uses the material from Part II as a basis for addressing a variety of practical issues, including temporal database design, temporal integrity constraints, and temporal querying and updating.
• Part IV examines the pertinent features of SQL:2011 and today’s SQL products.

The seminar is aimed primarily at technical specialists, though managers should benefit from it too (most of the technical material needed to understand the overall message is included in the seminar itself).