You can monitor queries using the Teradata Viewpoint Query Monitor portlet and other tools and utilities to identify poorly performing queries. Poor query performance is usually due to:
- Stale statistics. See Collecting Statistics.
- Poor query construction. See Finding and Fixing Problem Queries.
- Skewed query processing. See Managing Skewed Processing.
- Skewed table distribution. See Identifying and Fixing Skewed Tables.
- Locks that block queries from accessing needed data. See Identifying and Managing Blocked Queries.
This section also covers the performance issues related to transaction rollbacks, which occur when a query fails to complete. See Working with Transaction Rollbacks.