Sys_refcursor spawning maximum threads

Question

Hello All , i have a procedure which outputs 10 refcursors. It is called called by a .NET utility which then writes the data to 18 different flat files. The proc is of below format
CREATE OR REPLACE PROCEDURE FILE_EXTRACT
(OUTREC1 OUT SYS_REFCURSOR,
OUTREC2 OUT SYS_REFCURSOR,)
AS
BEGIN
OPEN OUTREC1 FOR
SELECT /*+PARALLEL(A,8)*/
COL1,COL2
FROM TABLE A;
OPEN OUTREC2 FOR
SELECT /*+PARALLEL(B,8)*/
COL1,COL2
FROM TABLE B;
I have used parallel hint because all the tables used in the queries a huge tables and this is a nightly batch job. The issue here is that i have expected oracle to use 8 processes for this execution so all my select statements have parallel hint with degree 8 , but unusaully the procedure is erroring out on production databases because of maximum number of connections are being spawned and the database is not able to create any new session.
When i debuged and did a quick test proc where i used only one out refcursor it ran only 9 threads . then i ran by adding one more out ref cursor it spawn 17 threads. I think its the way .NET is fetching data from each of these cursors.When i print the first refcursor i do see queries which are running for the second along with the first causing the parallel queries run more than expected. The cause of the problem here is all the refcursors are executed and waiting to return data. SO when .net starts reading first cursor the other queries also run.
Can somebody suggest me a better approach where we are not using lots of processes and still try to parallise things ??

Answer 1

I have checked the open cursor of my session:
SQL> SELECT o.sid, s.username, substr(machine,1,32),
count(*)
2  FROM v$open_cursor o, v$session s
3  WHERE o.sid = s.sid
4  GROUP BY o.sid, s.username, machine
5  HAVING COUNT(*) > 1
6  ORDER BY count(*) desc;
SID USERNAME
SUBSTR(MACHINE,1,32)
COUNT(*)
146 MAD                            bello
557This proves nothing as the cursors may have been closed after the SQL finished.
The problem is that for each row of data you are opening a ref cursor, but these opened cursors are not being closed for each row.
Can you not just join to the address table that is in the function and retrieve the data as an additional column? It doesn't really seem like you need to use a function in this case.
Also bear in mind that calling user defined functions from within SQL causes a performance issue when dealing with lots of rows of data due to the context switching between SQL and PL/SQL that has to take place.
If you can do it just in SQL then do that. Ony resort to PL/SQL when absolutely necessary.