Use a keyed sequence access path for database files

A keyed sequence access path for database files is based on the contents of the key fields as defined in data description specifications (DDS). This topic describes how the key fields are arranged for the file.

This type of access path is updated whenever records are added or deleted, or when records are updated and the contents of a key field is changed. The keyed sequence access path is valid for both physical and logical files. The sequence of the records in the file is defined in DDS when the file is created and is maintained automatically by the system.

Key fields defined as character fields are arranged based on the sequence defined for EBCDIC characters. Key fields defined as numeric fields are arranged based on their algebraic values, unless the UNSIGNED (unsigned value) or ABSVAL (absolute value) DDS keywords are specified for the field. Key fields defined as DBCS are allowed, but are arranged only as single bytes based on their bit representation.

• Arrange key fields using an alternative collating sequence
  Keyed fields defined as character fields can be arranged based either on the sequence for EBCDIC characters or on an alternative collating sequence.
• Arrange key fields using the SRTSEQ parameter
  You can arrange key fields containing character data according to several sorting sequences available with the SRTSEQ parameter.
• Arrange key fields in ascending or descending sequence
  Key fields can be arranged in either ascending or descending sequence.
• Use more than one key field
  You can use more than one key field to arrange the records in a database file. The key fields do not have to use the same sequence.
• Prevent duplicate key values
  DB2 Universal Database™ for iSeries™ allows records with duplicate key values in your files. However, you might want to prevent duplicate key values in some of your files.
• Arrange duplicate keys
  If you do not specify the UNIQUE keyword in data description specifications (DDS), you can specify how the system stores records with duplicate key values, if duplicate key values occur.