A system and method are provided for pattern discovery in input heterogeneous logs having unstructured text content and one or more fields. The system includes a memory. The system further includes a processor in communication with the memory. The processor runs program code to preprocess the input heterogeneous logs to obtain pre-processed logs by splitting the input heterogeneous logs into tokens. The processor runs program code to generate seed patterns from the preprocessed logs. The processor runs program code to generate final patterns by specializing a selected set of fields in each of the seed patterns to generate a final pattern set.