private KeyPrefix buildKey(final int k) {
        return KeyPrefix.create("key" + k);
    }
This is meant to be compared to
stroom.pipeline.refdata.store.offheapstore.TestRefDataOffHeapStore#testLookupPerf()
stroom-state/stroom-planb-impl/src/test/java/stroom/planb/impl/db/TestStateLookupImpl.java