The SQL*Plus auto trace is another method to get actual execution plan with some additional statistics. When set to ON automatically display execution plan after each SQL statement with Statistics

1. Query that will return the trace file for a given session or for all sessions attached to the database. You should be connected as SYSDBA
2. Automation for Enabling and disabling SQL Trace

SQL Trace and TKPROF let you to accurately assess the efficiency of the SQL statements when an application runs. For best results, use these tools with EXPLAIN PLAN rather than using EXPLAIN PLAN alone.

An execution plan is the sequence of operations Oracle performs to run the statement. The EXPLAIN PLAN statement displays execution plans chosen by the Oracle optimizer for SELECT, UPDATE, INSERT, and DELETE statements.

When a SQL query is submitted to an Oracle database, Oracle query optimizer decide how to access the data. The process of making this decision is called query optimization, Oracle looks for the optimal way to retrieve the data, using the execution path.