Please reply:how to avoid extra trailing spaces while using cursor sharing

Question

i am using cursor sharing with FORCE or SIMILAR.
what is the solution to avoid extra trailing spaces without any java code change.
do we have any option in oracle to avoid extra trailing spaces during the query processing ?
I am using Oracle 10g
CURSOR SHARING is a feature in which multiple sql statements
which are same will have a shared cursor (in the library cache) for an oracle session,
i.e, the first three steps of the sql processing (hard parse, soft parse, optimization)
will be done only the first time that kind of statement is executed.
There are two ways in which similar SQL statements with different condition values can be made to "SHARE" cursor during execution:
1. Writing SQLs with Bind Variables: SQLs having no hard coded literals in them
For e.g., the query below
SELECT node.emp_name AS configid
FROM emp node
WHERE emp_no = :1
AND dept_no =
DECODE (SUBSTR (:2, 1, 3),
:3, :4,
(SELECT MAX (dept_no)
FROM emp
WHERE emp_no = :5 AND dept_no <= :6)
AND node.dept_type = :7
ORDER BY node.emp_name
Here all the variables are dynamically bound during the execution. The ":X" represents BIND Variable and the actual values are bound to the SQL only at the 4th step of the execution of the SQL.
In applications: The queries written with "?" as bind variables will be converted into ":X" and are sqls with Bind Variables.
2. The CURSOR_SHARING parameter: Only Useful for SQL statements containing literals:
For eg., the query below:
SELECT node.emp_name AS configid
FROM emp node
WHERE emp_no = 'H200'
AND dept_no =
DECODE (SUBSTR (:1, 1, 3),
'PLN', :2,
(SELECT MAX (dept_no)
FROM emp
WHERE emp_no = :3 AND dept_no <= :4)
AND node.dept_type = :5
ORDER BY node.emp_name
In the query above, there are two hard coded literals H200 , PLN. In this case when the same SQL executed with different values like (H2003 , PLN), oracle will create a new cursor for this statement and all the first three steps ( hard & soft parse and optimization plan) needs to be done again.
This can be avoided by changing the CURSOR_SHARING parameter which can be set to any of three values:
1. EXACT: Causes the mechanism not be used, i.e. no cursor sharing for statements with different literals. This is the default value.
2. FORCE: Causes unconditional sharing of SQL statements that only differ in literals.
3. SIMILAR: Causes cursor sharing to take place when this is known not to have any impact on optimization.
So, FORCE and SIMILAR values of the parameter will be helping in cursor sharing and improve the performance of the SQLs having literals.
But here the problem arises if we use the FORCE and SIMILAR other than EXACT.
alter session set cursor_sharing ='EXACT'
select 1 from dual;
'1'
1
alter session set curson_sharing='FORCE'
select 2 from dual;
'2'
2
alter session set curson_sharing='SIMILAR'
select 3 from dual;
'3'
3
So, this will give extra trailing spaces in when we retrieve from java method and any
further java processing based on the hardcoded literal values will fail. this needs lot of
effort in remodifying the existing millions of lines of code.
My question is i have to use cursor sharing with FORCE or SIMILAR and can't we do the trimming
from the oracle query processing level ?
please help me on this ?
Message was edited by:
Leeladhar
Message was edited by:
Leeladhar

Answer 1

Please reply to this thread
How to avoid extr trailing spaces using Cursor sharing opton FORCE, SIMILAR