This section describes access methods, explains why you
create user-defined access methods, and shows you how to create user-defined
access methods
Built-in access methods
An access method consists of software routines that open
files, retrieve data into memory, and write data to permanent storage
such as a disk.
User-defined access methods
You can create user-defined primary 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.
Access-method components
When you add an access method to IBM Informix, you add, or register,
a collection of C user-defined routines (UDRs) in the system catalog.
These UDRs take advantage of an Informix application programming
interface (API), the Virtual-Table Interface (VTI).
Access method flow
To apply a user-defined access method, the database server
must locate the access-method components, particularly the purpose
functions.
Release date: March 2014