In {HEAD ~ some embodiments}, {TAIL ~ the sub strings} associated with the indices are created based on a historical analysis of queries received from database users 
In { HEAD ~ some embodiments } , { TAIL ~ the sub strings } associated with the indices are created based on a historical analysis of queries received from database users
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH