To better understand the performance on different
keyword queries with various characteristics, several
keyword queries with 2-6 keywords were used. To
evaluate the performance for keyword queries with
different selectivities, tests were performed using
various sets of keywords with keyword frequency
ranges of 1 to 100 (low), 101 to 10 000 (medium), and
above 10 000 (high). The computation performance
was based on elapsed time.