User-defined access methods

This publication explains how to create secondary access methods that provide SQL access to non-relational and other data that does not conform to built-in access methods. For example, a user-defined access method might retrieve data from an external location or manipulate specific data within a smart large object.

An access method can make any data appear to the end user as rows from an internal relational table or keys in an index.. With the help of an access method, the end user can apply SQL statements to retrieve nonstandard data. Because the access method creates rows from the data that it accesses, external or smart-large-object data can join with other data from an internal database.

This publication calls the index that the access method presents to the user a virtual index.