database contention

Hi,

I can see multiple insert and select statement which is causing temp space  contention as shown following event. Please suggest if something can be done to resolve the issue.

insert /*+ append */ into sys.ora_temp_1

select /*+  parallel_index(t, "ING_FDK_MV

insert /*+ append */ into sys.ora_temp_2

insert /*+ append */ into sys.ora_temp_4

Database=4 RAC node 11.2.0.2

Events:

WAITED  enq: PS - contention  

WAITED  enq: PS - contention  

  WAITED  enq: PS - contention  

Thanks!