Describe access paths for database files

These topics discuss the different ways of describing access paths for database files.

An access path describes the order in which records are to be retrieved. Records in a physical or logical file can be retrieved using an arrival sequence access path or a keyed sequence access path. For logical files, you can also select and omit records based on the value of one or more fields in each record. A key field is a field used to arrange the records of a particular type within a file member.

• Use arrival sequence access path for database files
  The arrival sequence access path for database files is based on the order in which the records arrive and are stored in the file. This topic discusses what kind of file can use arrival sequence access path and how you can use the path to describe the file.
• 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.
• Use existing access path specifications
  The keyword REFACCPTH in data description specifications (DDS) allows you to use another file's access path specifications. When the file is created, the system determines which access path to share.
• Use floating-point fields in database file access paths
  The collating sequence for records in a keyed database file depends on the presence of the SIGNED, UNSIGNED, and ABSVAL keywords in data description specifications (DDS). For floating-point fields, the sign is the farthest-left bit, the exponent is next, and the significant is last.