Introduction to Access Paths › Recognizing the Basic Properties of Access Paths › Span (SPN) Access Path

Span (SPN) Access Path

A SPN access path specifies a keyed multi-format access path. It can be used to describe to the edit and display transaction functions how records are to be retrieved from a pair of related files. These files possess a common foreign key. These files must be related by an Owned by or Refers to relation. The SPN access path must be created over the owning or referred to file. This access path type:

• Initially defaults to those keys defined by the key relations of the based-on files but can be overridden to an alternative key sequence
• Allows virtual fields to be specified on the access path relations
• Must be created explicitly
• Is associated with a RTV access path that points to an associated UPD access path used to carry out any updates to the based-on file
• Allows explicit selection of multiple access path formats
• Defaults to the virtual fields of the based-on file's relations; these are then present on the access path's relations.