Bind variable & LIKE :1 - Performance issue

Question

I'm using ODP.NET version 10.2 and I'm facing a performance problem with LIKE key word in statements.
I'm doing the following :
OracleConnection conn = new OracleConnection();
conn.ConnectionString = connectionString;
string strQuery;
OracleCommand cmd = new OracleCommand();
cmd.Connection = conn;
strQuery = "SELECT field FROM table WHERE field LIKE :1";
cmd.Parameters.Add(":1", OracleDbType.Varchar2, 2, "x%",ParameterDirection.Input);
-> This takes quite a long time to retrieve the data.
If I do the following (without Parameters.Add) it flies :
strQuery = "SELECT field FROM table WHERE field LIKE 'x%'";
cmd.CommandText = strQuery;
OracleDataAdapter da = new OracleDataAdapter();
da.SelectCommand = cmd;
DataSet ds = new DataSet();
da.Fill(ds, "table");
What am I doing wrong ?
Thanks in advance
Philippe

Answer 1

Hi,
Is this behavior specific to ODP.NET? Do you get the same behavior testing sqlplus with bind variables? If you're not sure how, here's how you can try it..
Cheers,
Greg
SQL> var abc varchar2(100);
SQL> exec :abc := 'K%';
PL/SQL procedure successfully completed.
SQL> set timing on
SQL> select * from emp where ename like :abc;
EMPNO ENAME JOB MGR
HIREDATE SAL COMM DEPTNO
7839 KING PRESIDENT
17-NOV-81 5000 10
Elapsed: 00:00:00.00
SQL> select * from emp where ename like 'K%';
EMPNO ENAME JOB MGR
HIREDATE SAL COMM DEPTNO
7839 KING PRESIDENT
17-NOV-81 5000 10
Elapsed: 00:00:00.01
SQL>