TAILIEUCHUNG - Inclusion of new types in relational database systems

The collection of built-in data types in a data base system (. integer, floating point number, character string) and built-in operators (. +, -, *, /) were motivated by the needs of business data processing applications. However, in many engineering applications this collection of types is not appropriate. For example, in a geographic application a user typically wants points, lines, line groups and polygons as basic data types and operators which include intersection, distance and containment. In scientific application, one requires complex numbers and time series with appropriate operators. In such applications one is currently required to simulate these data types | INCLUSION OF NEW TYPES IN RELATIONAL DATA BASE SYSTEMS Michael Stonebraker EECS Dept. University of California, Berkeley Abstract This paper explores a mechanism to support user-de®ned data types for columns in a relational data base system. Previous work suggested how to support new operators and new data types. The contribution of this work is to suggest ways to allow query optimization on commands which include new data types and operators and ways to allow access methods to be used for new data types. 1. INTRODUCTION The collection of built-in data types in a data base system (. integer, ¯oating point number, char- acter string) and built-in operators (. +, -, *, /) were motivated by the needs of business data processing applications. However, in many engineering applications this collection of types is not appropriate. For example, in a geographic application a user typically wants points, lines, line groups and polygons as basic data types and operators which include intersection, distance and containment. In scienti®c application, one requires complex numbers and time series with appropriate operators. In such applications one is currently required to simulate these data types and operators using the basic data types and operators pro- vided by the DBMS at substantial inef®ciency and complexity. Even in business applications, one some- times needs user-de®ned data types. For example, one system [RTI84] has implemented a sophisticated date and time data type to add to its basic collection. This implementation allows subtraction of dates, and returns "correct" answers, . "April 15" - "March 15" = 31 days This de®nition of subtraction is appropriate for most users; however, some applications require all months to have 30 days (. programs which compute interest on bonds). Hence, they require a de®nition of sub- hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh This research was sponsored by the . Air Force Of®ce of Scienti®c Research Grant 83-0254 and the .

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