The DB2 Distributed Data Facility

The data adapter fully supports the DB2 Distributed Data Facility (DDF). The following sections describe data adapter support for DB2 DDF.

In this section: File Descriptions for DDF Accessing Tables at Different Locations

File Descriptions for DDF

To identify the DB2 subsystem, include the DB2 LOCATION attribute in the TABLENAME parameter of the Access File. This identifies the table to FOCUS as a remote table. The syntax is

TABLENAME=[location.][creator.]table

where:

location

Is the DB2 subsystem location name; 16 characters maximum.

creator

Is the authorization ID of the table's creator; 8 characters maximum.

table

Is the name of the RDBMS table or view; 18 characters maximum.

Note:

• The TABLENAME value can have be a maximum of 44 characters (including the required periods).
• AUTODB2 can create Access Files that specify three-part table names. For information, see Automated Procedures.

Accessing Tables at Different Locations

The data adapter allows you to join tables at different locations. FOCUS performs the join since DB2 does not permit a single SQL statement to reference data at more than one location.

The data adapter determines that FOCUS must manage the join based on the presence and value of the LOCATION attribute in the TABLENAME parameter of one or more of the tables referenced in the request. If all remote tables have the same LOCATION attribute, the data adapter optimizes the join to the RDBMS. If you use local aliases for remote tables (and, therefore, have no LOCATION attribute in the table name), you must SET OPTIMIZATION=OFF for each request that joins tables from more than one location.

FOCUS automatically appends a "FOR FETCH ONLY" clause to SELECT statements generated by TABLE requests. This clause assists the DB2 optimizer in access path selection and offers substantial performance improvements.