Accelerated sub-string searches on large data sets can be performed using filtering processes that can improve or optimize run time performance. A first filtering process can include partitioning a binary tree into sections to enable an exact search to replace a substring search for part of the binary tree and for part of the binary tree to be potentially excluded from substring searching. A second filtering process can include comparing count representations of entries in the binary tree and of a received input string to potentially further exclude entries from substring searching.