{HEAD ~ Checkpointing} would enable {TAIL ~ the relational database system} to implement restartable queries, and thus database performance is increased 
enable
{ HEAD ~ Checkpointing } would enable { TAIL ~ the relational database system } to implement restartable queries , and thus database performance is increased
HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH