Siemens V 4.0 User Manual

GINA V4.0 System Administrator Guide – September 2000

33

Customizing the database layout

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GINA offers you the option of customizing the database layout and the access privileges.
One aspect of this relates to the assignment of names of database tables for persistent
classes, whereby the default is that the class names of the specialist models are also used
to designate the database tables. However, this may cause problems if the maximum per-
mitted length for identifiers is subject to specific restrictions.

For example, table names are limited to 18 characters in the INFORMIX version used.
Since GINA itself requires a character as a prefix, class names that are longer than 17 char-
acters must be mapped to a shorter table name.

❍ ❍ ●

Another aspect is the definition of the actual storage space for tables in the physical data-
base structures, i.e. the dbspaces. Performance requirements can be considered here, and
the optimization functions of the database system can be used.

In terms of access privileges, requirements with regard to access protection are defined at
database or table level. The functionality also depends on the concrete database server.

The specifications for this customization are defined in description files. These are made
known to the

 mgen2

generator using the

 -r

and

 -t

options [14]. The generator then

creates an appropriately modified database schema. The following description files exist:

–

the pfx file and

–

the tbl file