SQL Query Optimization Messages

SQL Query Optimization Messages

You can tune the performance of SQL queries by using the SQL Query Optimization Messages to determine:

• What processing steps the data access plan contains,
• Why those processing steps were selected, and
• The estimated and actual costs of those processing steps.

There are two main types of Optimization messages:

• Bind Time (see Bind-time Messages):

  Summary:

  Join order and method, sort required, total estimated cost.

  Detail:

  Detail estimates for each join order/method combination.

• Execution Time (see Execution-Time Messages):

  Summary:

  Rows read from index and data, rows qualified, rows sorted, and so on, during the time the plan was open.

  Detail:

  Same data as summary, but for each execution of a statement.