1. A computer-implemented method for processing log data, comprising: receiving log data that comprises a plurality of events, an event including one or more fields; and for each event in the plurality of events: storing, in a buffer, the event; identifying a first value of a first field of the event; identifying a first minimum value that indicates a minimum value of the first field of all of the events stored in the buffer, wherein the first minimum value is stored in a metadata structure that comprises information about contents of the buffer; determining whether the first minimum value exceeds the first value; and responsive to determining that the first minimum value exceeds the first value, updating the metadata structure by replacing the first minimum value with the first value.