Performance when too many active tasks running

[hongguoan]

Hi:
We have performance issue after activiti deployed 3 months.
We found out 43% of oracle CPU time is spending on table scan on

select * from ACT_RU_TASK where PARENT_TASK_ID_ = :1

SQL> select count(*) from ACTIVITI_ADM.ACT_RU_TASK;

  COUNT(*)
———-
    185276

SQL> select last_analyzed from dba_tables where table_name='ACT_RU_TASK';

LAST_ANAL
———
08-JAN-16

SQL> select distinct PARENT_TASK_ID_ from ACTIVITI_ADM.ACT_RU_TASK;

We do have long running task that could last years, and all parent_task_id is null.
Is there any way for us to improve the performance on this?
Thanks
PARENT_TASK_ID_
—————————————————————-

[jbarrez]

I don't think 185276 rows should be a problem for modern databases.
Do you know which API/query call executes this SQL? I can see it might be executed when deleting a task (for cleaning up via parent).