1. A data-processing system comprising: one or more processors; one or more computer-readable media; and a routine that executes on the one or more processors to analyze a stream of digitally encoded log data output from a computational system and stored in the computer-readable media by maintaining a historical dynamic normalcy graph of meta-data that represents statistical patterns within the stream of log data; detecting changes within the stream of log data; and identifying abnormalities in the stream of log data based on the statistical patterns and on detected changes within the stream of log data.