Transaction log management

摘要

A transaction processing system comprising a transaction log, a log management policy, a profile and a log manager, and method for managing the transaction log are provided. The method comprises maintaining a transaction log of recoverable changes made by transaction processing tasks, each task having an associated transaction type; storing a log management policy including at least one log threshold and a plurality of possible actions associated therewith; and storing a profile of log resource usage characteristics of tasks for different types of transactions. Usage of the log by transaction processing tasks is monitored to determine when a log threshold is reached. The profile indicates the normal logging behavior of particular types of transaction by identifying ranges of acceptable values for a plurality of log resource usage characteristics. Such characteristics may include time taken for a task to complete, CPU resource consumed, number of log records made, etc. From a comparison of the profile behavior with the current log resource usage of a task which has been identified as holding up trimming of the log, likelihood that the identified task having entered an invalid loop and represents a ‘bad’ program, rather than simply validly taking a long time to complete can be inferred. Thus the most appropriate action can be selected and taken.

主权项

1. A method, within a transaction processing system executing a two-phase commit protocol, for managing a transaction log of a plurality of recoverable changes made by transaction processing tasks, each recoverable change corresponding to a unit of work performed by a particular transaction processing task having an associated transaction type, comprising:
monitoring usage of the transaction log by the transaction processing tasks; comparing a measure of log space within the transaction log with a threshold; upon a determination that the threshold has been met,
identifying, from all active tasks, an active task having an oldest log entry within the transaction log;identifying a transaction type of the identified active task having the oldest log entry;identifying actual log resource usage of the identified active task having the oldest log entry;comparing the actual log resource usage with a typical log resource usage for the identified transaction type; andselecting, based upon the comparison between the actual log resource usage and the typical log resource usage, one of a plurality of log size reduction actions.