IFX_EXTDIRECTIVES

The IFX_EXTDIRECTIVES environment variable specifies whether the query optimizer allows external query optimization directives from the sysdirectives system catalog table to be applied to queries in existing applications. The IFX_EXTDIRECTIVES environment variable is set on the client.

You can specify either ON and OFF or 1 and 0 to set the environment variable.

>>-setenv--IFX_DIRECTIVES--+-1-+-------------------------------><
                           '-0-'
 

1

External optimizer directives accepted

0

External optimizer directives not accepted

Queries within a given client application can use external directives if both the EXT_DIRECTIVES parameter in the configuration file of the database server and the IFX_EXTDIRECTIVES environment variable setting on the client system are both set to 1 or ON. If IFX_EXTDIRECTIVES is not set, external directives are supported only if the ONCONFIG parameter EXT_DIRECTIVES is set to 2. The following table summarizes the effect of valid IFX_EXTDIRECTIVES and EXT_DIRECTIVES settings on support for external optimizer directives.

The database server interprets any EXT_DIRECTIVES setting besides 1 or 2 (or no setting) as equivalent to OFF, disabling support for external directives. Any value of IFX_EXTDIRECTIVES other than 1 has the same effect for the client.

For information on how to define external optimizer directives, see the description of the SAVE EXTERNAL DIRECTIVES statement of SQL in the IBM Informix: Guide to SQL Syntax. For more information about the EXT_DIRECTIVES configuration parameter, see the IBM Informix: Administrator's Reference. For more information on the performance impact of directives, see your IBM Informix: Performance Guide.