Sampling transactions from multi-level log file records

A method for sampling transactions from multi-level log file records, a log file contains operation records, each operation record is of a certain type, each operation record is associated with a transaction, the method comprising:

• reading a plurality of operation records from the log file into a record store;
• sampling records of the plurality of operation records of each operation record type at a predefined sampling rate;
• identifying operation records in the plurality of operations records associated with completed transactions of which the sampled operation records are associated;
• and
• extracting the identified operation records from the record store into a data store.