Joining database files: Performance considerations

You can do the following to improve the performance of join logical files:

• If the physical files you are joining have a different number of records, specify the physical file with fewest records first (first parameter following the JOIN keyword).
• Consider using the DYNSLT keyword. See Dynamic Select/Omit for more details.
• Consider describing your join logical file so it can automatically share an existing access path. See Using Existing Access Paths for more details.

  Note:

  Join logical files always have access paths using the second field of the pair of fields specified in the JFLD keyword. This field acts like a key field in simple logical files. If an access path does not already exist, the access path is implicitly created with immediate maintenance.