VPD Performance

Question

Hi,
I need to use VPD feature for my project, so testing the performance hit if I use VPD.
I have table CUST_MAST which hold details for customer. I want to apply VPD policy on this table in such a way that branch employee can see only customers under their own branch.
So that I added one field BRANCH_CODE in CUST_MAST table, this field will hold branch code number and policy function will return predicate like WHERE BRANCH_CODE = 'CODE VALUE'. so I can grantee that employee can see only own branch customers. Its working fine.
Now I want to test performance hit with VPD. So I am testing INSERT,SELECT,UPDATE, DELETE operation on this table. I created one more table with same structure as CUST_MAST e.g CUST_MAST_VPD and added branch_code. The policy function is applied on CUST_MAST_VPD
CUST_MAST ---------- Structure before adding BRANCH_CODE
cust_no
cust_name
CUST_MAST_VPD ----------- Structure after adding BRANCH_CODE
cust_no
cust_name
branch_code
Policy Function
create or replace function filter_branch_data
p_schema in varchar2,
p_table in varchar2
return varchar2
as
l_retstr varchar2(2000);
begin
if(SYS_CONTEXT ('hr_ctx', 'BRANCH_CODE') = 'ALL') then
l_retstr := null;
else
l_retstr := 'BRANCH_CODE = '||''''|| SYS_CONTEXT ('hr_ctx', 'BRANCH_CODE')||'''';
end if;
return l_retstr ;
end;
Policy Type is
dbms_rls.add_policy (
object_schema => 'DEV',
object_name => 'CUST_MAST_VPD',
policy_name => 'perform_vpd_test',
function_schema => 'DEV',
policy_function => 'filter_branch_data',
statement_types => 'SELECT,INSERT,UPDATE,DELETE,INDEX',
update_check => TRUE,
policy_type => dbms_rls.context_sensitive
Table has following Indexes
Index for non policy table CUST_MAST
Unique Index on cust_no
Index for policy table CUST_MAST_VPD
Unique index on cust_no
Index on bank_code
When I tried to Insert,select,update and delete operation with 10000 records
but I got a apposite result, with VPD my performace got improved,
INSERT - takes less time to insert in policy table i.e CUST_MAST_VPD -- performance improved
SELECT - takes more time to select from policy table i.e CUST_MAST_VPD --
performance decreased
UPDATE - takes less time to update records in policy table i.e CUST_MAST_VPD -- performance improved
DELETE - takes less time to delete from policy table i.e CUST_MAST_VPD --
performance imporved
MY QUESTION
As per my thinking It should reduce the performance but how it is possible that for INSERT,UPDATE and DELETE performance is improved ?

Answer 1

Hi,
Thanks for reply.
POLICY table has 2 indexes
Unique Index on cust_no
Index on branch_code.
I made mistake in previous Post there is no field bank_code its a brach_code.