TWB_STATUS private log captures job performance data at different stages of the job. These stages, also known as operator processing methods, include the following:
- Initialization of operators (INITIATE method)
- Data acquisition performed by the operators (EXECUTE method)
- Checkpoint processing (CHECKPOINT method)
- Restart processing (RESTART method)
- Termination of operators (TERMINATE method)
By default, Teradata PT collects performance data for each instance of the operator at the beginning and end of each method. Teradata PT also provides a tbuild command option for specifying the interval (in seconds) for collecting performance data.
The performance data can be viewed as a relational table, which contains the following fields:
- The name of the job step
- The name of the operator
- Instance number
- Processing method (INITIATE, EXECUTE, CHECKPOINT, RESTART, TERMINATE)
- Start time of a method
- End time of a method
- CPU utilization (in seconds) for a method
- Number of buffers transferred since the beginning of data acquisition
- Number of rows sent (or received) by the instance since the beginning of data acquisition
This information is useful for evaluating the performance of a job in terms of throughput and the cost of exporting and loading of data by each operator. It is also useful for capacity planning by collecting the performance data for a period of time, summarizing the CPU utilization and elapsed time for each job, and then determining the trend of performance for the overall loading and exporting processes for a specific system configuration.