Monitoring a Global Transaction

Use the onstat -x command to track open transactions and determine whether they have been heuristically rolled back.

For example, in the output, an H flag in the flags field identifies a heuristic rollback, the G flag identifies a global transaction, the L flag indicates loosely-coupled mode, and the T flag indicates tightly-coupled mode.

The curlog and logposit fields provide the exact position of a logical-log record. If a transaction is not rolling back, curlog and logposit describe the position of the most recently written log record. When a transaction is rolling back, these fields describe the position of the most recently "undone" log record. As the transaction rolls back, the curlog and logposit values decrease. In a long transaction, the rate at which the logposit and beginlg values converge can help you estimate how much longer the rollback is going to take.

For more information on and an example of onstat -x output, see the IBM Informix Administrator's Reference.

You also can use the onstat -u and onstat -k commands to track transactions and the locks that they hold. For details, see the monitoring transactions section in your IBM Informix Performance Guide. For a description of the fields that onstat -x displays, see the IBM Informix Administrator's Reference.