Comparing hash table with Gk arrays on variable-length reads. Experiments on the Khoisan Roche 454® dataset (variable length reads) with a hash table and Gk arrays (with variable-length read option). (a) Maximal space consumption of each index for several read numbers and values of k (the error bars represent the variation in space usage, depending on k). The lower space consumption corresponds to a lower k. (b) Index construction time (the lighter gray corresponds to the smaller k). (c) Query computation time for 600,000 reads depending on the value of k.