bdfg1m0hGeneral Information


The TPFDF/Distributed Data Access (DDA) Feature

The TPFDF/DDA feature propagates data from a TPFDF database (hierarchical) to a DATABASE 2 (DB2) database (relational).

The database administrator defines the correlation between fields in the hierarchical database (index keys, index levels, and so on) and fields in the relational database (data row, column, and so on). Extracting fields from the TPFDF file (or files) to build the SQL data row is defined centrally for any TPFDF file that contains data to be propagated.

When any file-modification command is detected, the central definition is checked to determine what action to take. This action can be as simple as ignoring LRECs with a particular ID (by not defining any actions for that ID) or can be as complicated as extracting index keys at each indexing level together with multiple fields in other files.

Figure 9 shows an SQL row built from fields in an index file (1) , a field in its detail file (2) , and a field in a different detail file (3). The extracted data can be a complete field or part of a field.

Figure 9. Data Extraction: From Index Files and Multiple Files


Figure 10 shows a simple one-to-one relationship between the TPFDF LREC data and the DATABASE 2 SQL data row.

Figure 10. Data Extraction: One-to-One Relationship between the Data Fields and Rows