Use the TableIndexTempExtension to specify the file extension used by the engine for the physical index file that makes up part of a logical DBISAM temporary table. Temporary tables are created when altering the structure of a table, optimizing the table, or for canned SQL result sets. The default value is ".idx". Be sure to always include the filename extension separator (.) when specifying the file extension.
This property cannot be set while the engine is active and the TDBISAMEngine Active property is True.