High invalidations in v$sqlarea for 1 query tag with "SQL Analyze"

Question

Hi All,
Hopefully post to the right forum, if not please do let me know. Thanks
I have one pre-production issue still don't have any clue how to move forward.
This is 2 RAC nodes in linux platform with Oracle 11.2.0.2
In the begininng this environment having a lot of performance issue, as huge "cursor: pin S wait on X", "latch: shared pool"
and "library cache:Mutex X" causing very bad performance in this environment. After oracle support suggest to disable few hidden paramter
and adjust some parameter, then it help to stablized the environment (according to oracle, the initial issue was caused by high version count).
But we still can find minimal "latch:shared pool" and "library cache:Mutex X" on top 5 wait event list on hourly AWR report.
This time oracle was saying it might caused by high reload and high invalidatiosn in sqlarea (not sure how true it is), luckily the event
did not caused the performance issue at this moment, but we're asking support how can we get rid of the "mutex/latch" event.
They give me one query to check the invalidations in v$sqlarea, and they suspect the high validation is causing by application.
  select *
  from v$sqlarea
  order by invalidations DESC;
  Weird thing is, there have one SQL tag with "SQL Analyze" always causing high invalidations. But we're not able to get more detail (base on SQL_ID)
in v$sql or v$session table. This SQL insert into v$sqlarea and remove within 1 or 2 seconds, hard to get more information.
And the statement is exactly the same, but don't know why SQL Analyze always checking on it.
This SQL is triggering by SYS user, and it is inserting into MLOG$ table (one of the application materialized log file)
  insert into "test"."MLOG$_test1" select * from "test"."MLOG$_test1"
  The v$sqlarea information as below, sometime the invalidations can hit more than 10,000
  SQL_ID              SQL_TEXT                                                                                        LOADS  INVALIDATIONS
  0m6dhq90rg82x /* SQL Analyze(632,0) */ insert into "test"."MLOG$_test" select * from "test"."MLOG$_test  7981    7981
  {code}
  Anyone have any idea how can i move forward for this issue? As Oracle is asking me to use SQLTXPLAIN get the detail?
  Please share with me if you have any idea. Thanks in advance.
  Regards,
  Klng                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

Answer 1

Hi Dom,
We have checked there have no SQL Tuning enable for this SQL_ID. Below is the optimizer parameter in this environment, the hidden parameter was changed which suggest by oracle support.
NAME                                 TYPE        VALUE
_optimizer_adaptive_cursor_sharing   boolean     FALSE
_optimizer_extended_cursor_sharing_r string      NONE
el
object_cache_optimal_size            integer     102400
optimizer_capture_sql_plan_baselines boolean     FALSE
optimizer_dynamic_sampling           integer     2
optimizer_features_enable            string      11.2.0.2
optimizer_index_caching              integer     90
optimizer_index_cost_adj             integer     10
optimizer_mode                       string      ALL_ROWS
optimizer_secure_view_merging        boolean     TRUE
optimizer_use_invisible_indexes      boolean     FALSE
optimizer_use_pending_statistics     boolean     FALSE
optimizer_use_sql_plan_baselines     boolean     TRUE
plsql_optimize_level                 integer     2
SQL> select * from dba_sql_plan_baselines;
no rows selected
SQL>yeah we did run the ash, but the high invalidation did not caputre in the report. Actually this SQL tag with sql analyze it gone from v$sqlarea very fast (only 1 or 2 seconds only).
Thanks.
Regards,
Klng