A directory that the dtSearch Engine can use to store temporary files.

Use TempFileDir to control the location of most temporary files that the dtSearch Engine creates, such as temporary files used for large file conversion operations or extraction of large documents stored in containers. If TempFileDir is blank, these files will be stored either in the PrivateDir or the Windows TEMP folder. dtSearch automatically deletes these temp files when the related operation is completed.  

Temporary file lists and sort buffers created during indexing are stored in the location specified by IndexJob.TempFileDir, or in the index folder if IndexJob.TempFileDir is blank.