Data Conversion - Information Systems Reengineering, Integration and Normalization - page 148

A template file can be created from an input network schema together with user
input to specify the record identifier. The template file consists of network schema
record types, their linkages to each other through different set types, and their re-
cord identifier. The record identifiers will contain the concatenation of record keys
and will be mapped into the relational database as primary keys or composite keys.
The template file will be used to unload the network database into sequential files.
The following shows the structure of a template file.

Record type template file
Name Key 1 ,.ey n Identifier Type Identifier 1 ..Identifier n Attr 1 ..Attr n

Name = network schema record type name
Key 1 ,.Key n = record key of the record type
Identifier Type = record identifier type,'F' for fully internally
identified, 'P' for partially internally identified
and 'I' for internally unidentifier.
Identifier 1 ..Identifier n = concatenated record keys with owner
record keys.
Attr 1 ..Attr n = attributes of the record type.

Besides the above template file, another template file is used to store all the set
linkage information. The following is the structure of the set linkage template file.

Set linkage template file

Owner Member Set linkage Name

Owner = owner record type name within the set
Member = member record type within the set
Set Linkage = name of the set that connects the owner and
member

Step 2—Unload network database into sequential files.
In the unload process, with the help of template files from step 1, an Unload pro-
gram will read all record occurrences of each record type of the network database