In one example, a data security system may determine prevalence of a file based query data for an object (e.g., a file or a hash or a file). An example algorithm may provide using a statistically justifiable estimate of the prevalence while storing few data records, and therefore may provide prevalence information in O(1) time complexity (i.e., constant time). Such an algorithm may be applied in near real-time to provide, e.g., an immediate response to a query for the prevalence of a file.