Stored Procedure Concurrency Problem 10g

Question

dear all,
Please any one could help on this my problem is appreciated.......
i'm generating ticket numbers using stored procedure as below .
i need to know followings .....(i'm using oracle 10g)
1 .Does oracle stored procedure handle concurrency by default or does db manage concurrency when we using sps or do we have handle concurrency inside a stored procedure?
2.when i generating ticket no using this stored procedure is there any concurrency issue when 100 clients are access it concurrently???
3. Is there issue or bug in my java code??????????
4.I have already used select for update statement but when i used that in db rowlocks are hanging and db become stuck .........
SELECT serial_no into newSerial FROM SERIAL_TAB WHERE BR_CODE=xbranch AND SCH_CODE = xscheme for update;
5. and in my where clause i pass branch and scheme eg:SELECT serial_no into newSerial FROM SERIAL_TAB WHERE BR_CODE=xbranch AND SCH_CODE =
xscheme;
when i run this sp oracle return the error 'more than one row return by query'
but when run query seperately it will return exactly one row for same brach code and scheme code no duplicates.
why this happen and it also happen to update statement it will ignore branch code and update for all schemes
UPDATE SERIAL_TAB SET serial_no=newSerial WHERE BR_CODE=xbranch AND SCH_CODE = xscheme;
what should i do ? sorry for my long question since i'm in deep trouble.....................
could any one can help please................................
in my java code i use transaction and setAutoCommit(false) when calling this sp
public String getTicketNo(String br,String sch){
//getconnection
//setAutoCommit(False);
//call sp get return value ;
//commit;
//if error rollback transaction
create or replace PROCEDURE sp_generate_ticket (
xbranch in varchar,
xscheme in varchar ,
xresult OUT VARCHAR
) AS
BEGIN
newSerial:=0;
SELECT serial_no into newSerial FROM SERIAL_TAB WHERE BR_CODE=xbranch AND SCH_CODE = xscheme;
newSerial:=newSerial+1;
UPDATE SERIAL_TAB SET serial_no=newSerial WHERE BR_CODE=xbranch AND SCH_CODE = xscheme;
--- do other operations -------------------------------------------------------------------------------------
END;
Best Regards,
Pradeep.
Edited by: user8958520 on Jan 1, 2012 10:02 PM

Answer 1

user8958520 wrote:
i need to know followings .....(i'm using oracle 10g)
1 .Does oracle stored procedure handle concurrency by default or does db manage concurrency when we using sps or do we have handle concurrency inside a stored procedure?Oracle is a multi-user and multi-process system. It supports concurrency. It also requires the developer to design and write "+thread safe+" code. Its concurrency cannot address and fix design flaws in application code.
2.when i generating ticket no using this stored procedure is there any concurrency issue when 100 clients are access it concurrently???That depends entirely on WHAT that procedure code does. And whether that code is thread safe.
4.I have already used select for update statement but when i used that in db rowlocks are hanging and db become stuck .........
SELECT serial_no into newSerial FROM SERIAL_TAB WHERE BR_CODE=xbranch AND SCH_CODE = xscheme for update;Horrible and utterly flawed approach. This forces serialisation. This means if that procedure is call by a 100 clients, only a SINGLE client can be serviced at a time. ALL OTHERS need to queue and WAIT.
Serialisation kills database performance.
What you have is a serious design flaw. Not an Oracle issue. And there is no magic solution to make this flawed approach work in a performant and scalable manner. This flaw introduces artificial contention. This flaw enforces serialisation. This flaw means that your application code WILL step on its own toes time and time again.
The proper solution is to fix this design flaw - and not use poorly conceived procedures such as sp_generate_ticket that violates fundamental concurrency principles.