Contents
What is the execution plan of an oracle statement?
A statement’s execution plan is the sequence of operations Oracle performs to run the statement. The row source tree is the core of the execution plan. It shows the following information: An ordering of the tables referenced by the statement
How to create an EXPLAIN PLAN in Oracle?
Oracle Performance Manager charts and Oracle SQL Analyze can automatically create and display explain plans for you. For more information on using explain plans, see Oracle Enterprise Manager Concepts. With the query optimizer, execution plans can and do change as the underlying optimizer inputs change.
Why does the execution plan differ from the EXPLAIN PLAN?
This can differ from the plan during actual execution for a SQL statement, because of differences in the execution environment and explain plan environment. Execution plans can differ due to the following: The execution and explain plan happen on different databases.
What does null mean in Oracle EXPLAIN PLAN?
The NULL in the Rows column indicates that the optimizer does not have any statistics on the table. Analyzing the table shows the following: You can also select the COST. This is useful for comparing execution plans or for understanding why the optimizer chooses one execution plan over another.
What happens when showplan text is off in SQL Server?
When SET SHOWPLAN_TEXT is OFF, SQL Server executes statements without generating a report with execution plan information. SET SHOWPLAN_TEXT is intended to return readable output for Microsoft Win32 command prompt applications such as the sqlcmd utility.
What are the sections of the SQL statement EXPLAIN PLAN?
This chapter introduces execution plans, describes the SQL statement EXPLAIN PLAN, and explains how to interpret its output. This chapter also provides procedures for managing outlines to control application performance characteristics. This chapter contains the following sections: