Clear SGA and Buffer Cache

The “Buffer Cache” has the recently used data blocks and the “SGA” has the SQL parse and the explain plan details. While executing SQL statements the details are stored in Buffer cache and the SGA, Hence the subsequent execution the SQL statement will be faster.

It is necessary to clear the above memories to find the exact execution time of the SQL statement (Mostly while working in SQL tuning...).

1:  SQL> alter system flush buffer_cache;  
2:  SQL> alter system flush shared_pool;