Interfacing Extensions To Indexes

PostgreSQL 7.3.4 Documentation
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# Chapter 14. Interfacing Extensions To Indexes

# 14.1. Introduction

The procedures described thus far let you define new types, new functions, and new operators. However, we cannot yet define a secondary index (such as a B-tree, R-tree, or hash access method) over a new type, nor associate operators of a new type with secondary indexes. To do these things, we must define an operator class for the new data type. We will describe operator classes in the context of a running example: a new operator class for the B-tree access 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 `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.

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Rules versus Triggers | Up | Access Methods and Operator Classes