Apart from the advantages of resolving many of the weaknesses cited in Section 25.2,
the main advantages of extending the relational data model come from reuse and sharing.
Reuse comes from the ability to extend the DBMS server to perform standard functionality
centrally, rather than have it coded in each application. For example, applications may
require spatial data types that represent points, lines, and polygons, with associated functions
that calculate the distance between two points, the distance between a point and a
line, whether a point is contained within a polygon, and whether two polygonal regions
overlap, among others. If we can embed this functionality in the server, it saves having to
define it in each application that needs it, and consequently allows the functionality to be
shared by all applications. These advantages also give rise to increased productivity both
for the developer and for the end-user.
Apart from the advantages of resolving many of the weaknesses cited in Section 25.2,
the main advantages of extending the relational data model come from reuse and sharing.
Reuse comes from the ability to extend the DBMS server to perform standard functionality
centrally, rather than have it coded in each application. For example, applications may
require spatial data types that represent points, lines, and polygons, with associated functions
that calculate the distance between two points, the distance between a point and a
line, whether a point is contained within a polygon, and whether two polygonal regions
overlap, among others. If we can embed this functionality in the server, it saves having to
define it in each application that needs it, and consequently allows the functionality to be
shared by all applications. These advantages also give rise to increased productivity both
for the developer and for the end-user.
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