Abstract: A method for processing data in the form of a stream of messages regarding, for example, stock price information, implemented using a computer system wherein the data may arrive at a rate faster than the computer system can process individual messages. Each message is tagged with a phase number as it arrives; only the data in the messages received at the end of a phase are stored in the computer system's database. Periodically, at the end of at least one phase and perhaps at the end of many phases depending on the rate messages are received, the computer queries its database to select information regarding the data. Algorithms, according to the present invention, allow the efficient selection of data by disregarding a portion of the information in some cases, and, in other cases, by finding the phase ranges wherein data messages overlap between phase ranges. In the former, data is lost; it the latter, data processing may be slowed. The selected information is then output.

Abstract: An event detection system allows data to be inserted while event conditions are being checked. Each record is assigned a time stamp as it is inserted into a database. Each event condition check is assigned a time stamp range. The event condition check then produces only those matches that have at least one record with a time stamp in the range and no record with a time stamp after the range. After each event condition check, the range is changed so that, in subsequent checks, no part of a previous range is duplicated and no time stamps are excluded from every checked range. As a result of this process, records may be inserted while event conditions are being checked.