Summary 

Preserve the existing settings in an index when clearing it before updating. 

Remarks 

Normally when an index is updated with ActionCreate=true in the IndexJob, the settings in the index (noise word lists, alphabet files, ICU version if any) are updated to the current settings. 

If the index already exists, and you want to clear it without modifying the settings that were originally used to create the index, set the flag dtsIndexCreatePreserveExistingSettings to tell dtSearch to read the settings currently in the index and preserve them when clearing the index.