Extspaces

An extspace is a logical name associated with an arbitrary string that signifies the location of external data. The resource that the extspace references depends on a user-defined access method for accessing its contents.

For example, a database user might require access to binary files encoded in a proprietary format. First, a developer creates an access method, which is a set of routines that access the data. These routines are responsible for all interaction between the database server and the external file. A DBA then adds an extspace that has the file as its target to the database. After the DBA creates a table in the extspace, the users can access the data in the proprietary files via SQL statements. To locate those files, use the extspace information.

An extspace need not be a filename. For example, it can be a network location. The routines that access the data can use information found in the string associated with the extspace in any manner.

For more information on user-defined access methods, see the IBM Informix Virtual-Table Interface Programmer's Guide. For more information on creating functions and primary access methods, see the IBM Informix Guide to SQL: Syntax.