Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Developer's Guide

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### Fixed Length CHAR Primary Keys

If an existing database table has a primary key column in which the values vary in length, but the type is `CHAR` instead of `VARCHAR`, the Application Server automatically trims any extra spaces when retrieving primary key values. It is not a good practice to use a fixed length `CHAR` column as a primary key. Use this feature with schemas that cannot be changed, such as a schema inherited from a legacy application.

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