Re: column masking in 10g

  • From: "Alexander Fatkulin" <afatkulin@xxxxxxxxx>
  • To: "David Boyd" <davidb158@xxxxxxxxxxx>
  • Date: Fri, 2 Mar 2007 13:07:22 +1000

Dave, It depends.

As long as you can get with simple SQL inline predicates the
performance will virtually be the same


create view v_t2 as
        select n, case mod(n, 2) when 0 then m else null end m
                from t2;

will perform virtually the same (from both elapsed time / latches) as
column masking using the policy function with the "return 'mod(n,2)=0'
" predicate. Don't forget I'm talking about _static_ policies here,


as long as you start using PL/SQL functions in a view - the
performance will significantly degrade (mostly due to context switches
between engines). The subquery caching (don't forget to declare
function as a deterministic) can help you but anyway - it has it's own

As always - don't forget to test for your own specific cases.

On 3/2/07, David Boyd <davidb158@xxxxxxxxxxx> wrote:

This works great for me.  Thanks so much.

Did you have experience on the performance between VPD and view?


Alexander Fatkulin,
Senior Oracle DBA

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