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5.14 Interfacing Extensions To Indexes

The procedures described thus far let you define new types, new functions, and new operators. However, we cannot yet define an index on a column of a new data type. To do this, we must define an operator class for the new data type. Later in this section, we will illustrate this concept in an example: a new operator class for the B-tree index method that stores and sorts complex numbers in ascending absolute value order.

Note: Prior to PostgreSQL release 7.3, it was necessary to make manual additions to the system catalogs pg_amop, pg_amproc, and pg_opclass in order to create a user-defined operator class. That approach is now deprecated in favor of using CREATE OPERATOR CLASS, which is a much simpler and less error-prone way of creating the necessary catalog entries.