An execution plan is the set of steps the database server uses to access information in the database related to a statement. The execution plan for a statement can be saved and reviewed, regardless of whether it was just optimized, whether it bypassed the optimizer, or whether its plan was cached from previous executions. A query execution plan may not correspond exactly to the syntax used in the original statement, and may use materialized views instead of the base tables explicitly specified in the query. However, the operations described in the execution plan are semantically equivalent to the original query.
You can view the execution plan in Interactive SQL or by using SQL functions. You can choose to retrieve the execution plan in several different formats:
There are two types of text representations of a query execution plan: short and long. Use the SQL functions to access the text plan. There is also a graphical version of the plan. You can also obtain plans for SQL queries with a particular cursor type by using the GRAPHICAL_PLAN and EXPLANATION functions.
To learn more about SQL Anywhere query processing, see the white paper "Query Processing Based on SQL Anywhere 12.0.1 Architecture" at http://www.sybase.com/detail?id=1096047.
Discuter à propos de cette page dans DocCommentXchange.
|Copyright © 2012, iAnywhere Solutions, Inc. - SQL Anywhere 12.0.1|