DB2 & IMS

Migration Challenges

6 Pages

Refer to the Installation Guide and the Data Sharing Planning and Administration manuals for details on data sharing mixed-mode issues.

Access Path Regression

Some shops have experienced changes in access paths for SQL statements bound in the V8 environment. There are many considerations here, including newly available access paths such as reverse index scanning and SQL statements that contain certain categories of predicates designed to coerce DB2 into choosing a particular path.

Some of these issues can be addressed by using DB2 V8 enhanced catalog statistics and by removing oddball predicates. One additional technique is to use optimizer hints. See the SQL Reference Guide for more information.

Enable NFM

The next step is the execution of CatMaint to convert many DB2 Catalog columns to Unicode and expanding the length of many to 128 bytes. While this job is running, you’re enabling NFM.

Typical Issues in ENFM

Job DSNTIJNE may abend due to lack of sort work space or other reasons. It may be restarted, but once started, there’s no falling back.

Execution time for this job is mostly a function of the size of your catalog, particularly tablespace SYSDBASE, since it contains tables, SYSCOLUMNS, SYSTABLES, and others whose columns are being expanded. IBM has made presentations and white papers on this process available on their DB2 support Website.

 “No New Function” NFM

6 Pages