  We describe Hokusai, a real time system which is able to capture frequency
information for streams of arbitrary sequences of symbols. The algorithm uses
the CountMin sketch as its basis and exploits the fact that sketching is
linear. It provides real time statistics of arbitrary events, e.g. streams of
queries as a function of time. We use a factorizing approximation to provide
point estimates at arbitrary (time, item) combinations. Queries can be answered
in constant time.
