Oracle SQL and PL/SQL : how to minimize execution time of retrieving members of the object (returned by user's function) - sql

Question

I wrote a function to get a number of values in an Oracle view. As functions can't return more then one value, I have used an object (with a signature of 8 numbers). This works, but not fine...
The execution time of a select query (and selecting from view, based on this query) is proportional to retrieved members number, i.e.:
retrieving 1 attribute consumes 1 second (it's equal to retrieve a WHOLE object, but object value is unusable for report),
retrieving 2 attributes consumes 2 seconds,
and so on...
This looks like Oracle executes PL function to get every member of returned object.
I think that function, returning varray(8) of numbers will not solve the problem too: eight implicit calls must be replaced by eight explicit subqueries. Can anybody solve this problem? (Except to rewrite to use a function returning one string, which I will try myself now...)
Here is the type declaration:
create or replace type "ARD"."PAY_FINE_FR_12_" AS object
(fed1 number
, reg1 number
, fed_nach number
, reg_nach number
, fed_upl number
, reg_upl number
, fed2 number
, reg2 number);

Answer 1

I will assume you have given meaningful names to your type's attributes. In which case you are returning not eight numbers but four pairs of numbers. This suggests a possible way of improving things. Whether it could actually solve your problem will depend on the precise details of your situation (which you have not provided).
Here is a type representing those number pairs, and a nested table type we can use for array processing.
create or replace type pay_pair as object
( pay_cat varchar2(4)
, fed number
, reg number )
/
create or replace type pay_pair_nt as table of pay_pair
/
This is a function which populates an array with four pairs of numbers. In the absence of any actual business rule I have plumped for the simplest possible example.
create or replace function get_pay_pairs
return pay_pair_nt
is
return_value pay_pair_nt;
begin
select
pay_pair (
case col1
when 1 then 'one'
when 2 then 'nach'
when 3 then 'upl'
when 4 then 'two'
else null;
end
, fed
, pay )
bulk collect into return_value
from v23;
return return_value;
end;
/
If you need the signature of the original type you can rewrite your function like this:
create or replace function get_pay_fine
return PAY_FINE_FR_12_
is
return_value PAY_FINE_FR_12_;
l_array pay_pair_nt;
begin
l_array := get_pay_pairs;
for i in 1..4 loop
case l_array(i).pay_cat
when 'one' then
return_value.fed1 := l_array(i).fed;
return_value.reg1 := l_array(i).reg;
when 'nach' then
return_value.fed_nach := l_array(i).fed;
return_value.reg_nach := l_array(i).reg;
when 'upl' then
return_value.fed_upl := l_array(i).fed;
return_value.reg_upl := l_array(i).reg;
else
return_value.fed2 := l_array(i).fed;
return_value.reg2 := l_array(i).reg;
end case;
end loop;
return return_value;
end;
I'll repeat, this is a demonstration of available techniques rather than a proposed solution. The crux is how your view supplies the values.