MySQL operational considerations

ON UPDATE and ON DELETE commands with CASCADE, SET NULL, or SET DEFAULT clauses are not captured by MySQL's binlog, so are not read by MySQL Reader.

When Compression is True, MySQL Reader compares the received before and after value for the UPDATE operation and sets the value in the data array in the WAEvent output only when the before and after values are not the same. This may cause problems when the target has an ON UPDATE constraint: the value in the source and target may not match.