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What causes execution plan to change?
1 Answer. The Optimizer takes the parsed representation of SQL statement and Statistics to generate final execution plan with the lowest cost. During this process the Optimizer generates multiple plans and compares them. Execution plans may change as the Optimizer inputs(Parsed SQL Statement and Statistics) get changed …
How would you find execution plan has changed?
You can check if the SQL execution plan has changed by using the Active Workload Repository (AWR). First, you need to find the SQL_ID for the relevant query. The view GV$SQL contains the most recent SQL. If you can’t find the query in this view, try DBA_HIST_SQLTEXT instead.
How do I delete an execution plan in Oracle?
Flush Bad SQL Plan from Shared Pool
- 1) FIND ADDRESS AND HASH_VALUE OF SQL_ID SQL> select ADDRESS, HASH_VALUE from V$SQLAREA where SQL_ID like ‘7yc%’; ADDRESS HASH_VALUE —————- ———- 000000085FD77CF0 808321886.
- 2) PURGE THE PLAN FROM SHARED POOL.
Is Romell Broom still alive?
Deceased (1956–2020)
Romell Broom/Living or Deceased
How to change the execution plan without changing the SQL query?
Example: For the below query, we want to force it to use parallel 4 Hint execution plan, But without changing the query. select count (*) from bigtab where weight in ( select distinct ( weight) from bigtab);
How to find elements affecting the execution plan?
You can use SQL Tuning Adviser, SQLTXPLAN, SQL Trace etc to make it easier to find the elements affecting the execution plan. Thanks for contributing an answer to Database Administrators Stack Exchange!
How to generate execution plan in Oracle Database?
How Oracle instance generates SQL_ID, HASH_VALUE and PLAN_HASH_VALUE for each SQL statement and its hash value is explained in the blog 3 values you should know when tuning the SQL statement. Ways of generating EXECUTION PLAN in Oracle Database explains the different ways of generating execution plan of SQL statement.
Which is the perfect execution plan for a query?
At the beginning query execution plan was perfect, database engine was using only index seeks and execution of the query was not longer that 200ms.