Don’t get confused about Logical Files, Views and Indices!

  Kungsholmen 2
  Jun 14, 2021

In this session the differences between the logical file types are explained. You’ll learn how to move business logic into the database by generating SQL views.

It will be explained why SQL needs first and foremost access paths, either in SQL indexes or keyed logical files. You’ll discover that even though an SQL index cannot be specified in an SQL statement, an SQL index can be used in conjunction with native I/O like any DDS described keyed logical file.


Long time ago, database objects were defined only with DDS (Data Description Specifications). Data access occurred with native I/O through DDS described (keyed) physical and logical files. But native I/O is only used in conjunction with RPG and COBOL. DDS is only known on the IBM i and furthermore stabilized since a few releases. The rest of the world uses SQL which also has become the strategical product for IBM for accessing and database data and creating database objects. While DDS provides only a single type of logical files, with SQL we are faced with two different types, respectively indexes and views.

      As far as good! But … Do we really need to move completely to SQL? What is the difference between these types of logical files? Which type of logical file has to be used in what situation? … And finally what about native I/O? 


Speaker: Birgitta Hauser, Toolmaker Advanced Efficiency GmbH

Session Handout: 35d Logical Files - Views - Indexes.pdf

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Birgitta Hauser

Software & Database Engineer, Toolmaker Advanced Efficiency GmbH

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