15.00 - Rules for Order Mapping Methods - Teradata Database

Teradata Database SQL Data Definition Language Detailed Topics

Teradata Database
Programming Reference

Rules for Order Mapping Methods

If you specify a method as the MAP routine for an ordering, it must obey the following rules:

  • It must be associated with the UDT for which this ordering is defined.
  • Its declared parameter list must be empty.
  • Its result data type must be a predefined data type.
  • Its predefined data type is valid except the following:

  • BLOB
  • CLOB
  • It must be declared to be DETERMINISTIC.
  • The name you specify for it in the ordering definition must be the name of a method contained within the SYSUDTLIB database.
  • If you create a structured UDT that might be used for a hash index definition, you must ensure that its ordering function never returns a null. If it does, Teradata Database aborts the request and returns an error to the requestor.
  • See “CREATE METHOD” on page 403 for details about method associations with UDTs, parameters, result data types, and the DETERMINISTIC option.