Created by Jerry Wang, last modified on Apr 21, 2016

Whether the Knowledge Article search is implemented via TREX or normal search is controlled by the global variable GV_TREX_SEARCH_POSSIBLE in class CL_CRM_QKNOART_RUN_BTIL.
The class will check whether there is available RFC destination for TREX search and it could be maintained via customizing Customer Relationship Management->Enterprise Intelligence->Configure RFC Destination:

If your configuration is correct however in the runtime still normal search is performed, you can debug the function module
CRM_SAF_API_SE_CONV_SS to figure out why ev_success fails to be set as abap_true.

more related configuration tables could be found in package EI_SAF_CUST.