The Sessions data collector collects all details for a session and the currently running request. SQL and Explain text is collected when the Enable SQL and Explain check box is selected and when SQL and Explain thresholds are met. Query band information is collected when the Enable SQL and Explain check box is selected and when either SQL and Explain thresholds are met or for utility sessions. The SQL and Explain thresholds can be set high or low and corresponding SQL and Explain text appears in the SQL and Explain tabs in query details views. The SQL associated with a query can help you target and optimize the query. The Explain text shows a query's progress through the Explain plan so you can optimize the query and change the Explain plan.
The Teradata Viewpoint system is configured to collect longer-running queries when SQL and Explain collection is enabled. Set the threshold lower to include shorter running queries, which may increase performance overhead.
The explain plan progress for all queries is updated at the collection rate of the Sessions collector. If you want to fetch the latest explain plan progress for a particular query more frequently than that rate, you can do so in the Query Monitor or Query Groups portlets. You can enable this feature per role by granting the Get Explain from DB permission for one or both of these portlets in Roles Manager.
Requirements for SQL and Explain Collection
The following are the requirements for SQL and Explain collection:
Request is in the DBC/SQL partition.
- Request must be active when collected.
- Request must exceed the threshold of 10 elapsed seconds or 5 CPU seconds (active thresholds are per request, not per session).
In addition, note the following for the utilities:
- Utility partition data sessions do not run SQL.
- Utility Control sessions in the DBC/SQL partition normally do not exceed the threshold.