How to check the Execution plan from a shared pool?
When we are observing any performance issue of the present SQL statement then we need to check the execution path of the culprit SQL statement. If it was already executed then we can obtain from the shared pool memory region of SGA in Oracle.
Using the following trick, you can get the execution path of executed SQL from the memory region of SGA. Using this trick, you can identify those heavily loaded queries which affect database performance degrading. During running 24/7 online database, performance tuning is the big thing and issue.
Check the execution plan with which the SQL statement that has already been executed has been compiled, obtaining the data from the SHARED POOL (v$sql).
In V$SQL I can see the sql statements that have already been executed, so that I can obtain the identifier (V $ SQL.SQL_ID) of any sql statement, to later consult the execution plan using the dbms_xplan package (DBMS_XPLAN.DISPLAY_CURSOR (SQL_ID)).
SQL> connect system / fabiancrea
SQL> select deptno, count (*) from scott.emp group by deptno;
DEPTNO COUNT (*)
SQL> select sql_id from v $ sql where sql_text = 'select deptno, count (*) from scott.emp group by deptno';
SQL> select * from table (dbms_xplan.display_cursor ('cxyqkgukrtpd6'));
SQL_ID cxyqkgukrtpd6, child number 0
select deptno, count (*) from scott.emp group by deptno
Hash value plan: 4067220884
| Id | Operation | Name | Rows | Bytes | Cost (% CPU) | Time |
| 0 | SELECT STATEMENT | | | | 7 (100) | |
| 1 | HASH GROUP BY | | 3 | 9 | 7 (15) | 00:00:01 |
| 2 | TABLE ACCESS FULL | EMP | 14 | 42 | 6 (0) | 00:00:01 |
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