Oracle SQL query fails only in one process: “ORA-01405: fetched column value is NULL”

Question

I'm trying to call a system stored procedure in a "plugin" that I've built. When I test my plugin out in a test application, it works fine. When I run the plugin in the targeted app I'm building it for, I get an exception from Oracle that doesn't make any sense.

I'm using Oracle server 11.2.0.1.0, and ODP.NET 2.112.2.0.

Here's the debug trace from ODP.NET from my test app:

(ENTRY) OracleConnection::OracleConnection(1)
(POOL)  New connection pool created for: "Data Source=orcl;User ID=scott;"
(ENTRY) OracleConnection::CreateCommand()
OpsSqlPrepare2():SQL: begin DBMS_AQADM.START_QUEUE(queue_name => 'MyQueue'); end;
(EXIT)  OpsSqlExecuteNonQuery(): RetCode=0 Line=877
(EXIT)  OracleCommand::ExecuteNonQuery()
(ENTRY) OracleConnection::Dispose()
(ENTRY) OracleConnection::Close()

And here's debug trace from ODP.NET from the same code running in the targeted app:

(ENTRY) OracleConnection::OracleConnection(1)
(POOL)  New connection pool created for: "Data Source=orcl;User ID=scott;"
(ENTRY) OracleConnection::CreateCommand()
OpsSqlPrepare2():SQL: begin DBMS_AQADM.START_QUEUE(queue_name => 'MyQueue'); end;
(EXIT)  OpsSqlExecuteNonQuery(): RetCode=0 Line=877
(EXIT)  OracleCommand::ExecuteNonQuery()
(ENTRY) OpsErrGetOpoCtx()
(ERROR) Oracle error code=1405; ORA-01405: fetched column value is NULL
(EXIT)  OpsErrGetOpoCtx(): RetCode=0 Line=137
(ENTRY) OracleConnection::Dispose()
(ENTRY) OracleConnection::Close()

I'm at a loss as to what could be different between the test/target applications. Both processes are running as members of the local Administrators group. Both are using the same connection string. Both are running the same .NET code, but with a different outcome from the database server. What could be going on here?

Answer 1

It turns out that my target application was executing my plugin code while in Distributed XA Transaction (MSDTC in my case). The call to DBMS_AQADM.START_QUEUE has an implicit COMMIT; that I wasn't aware of. The error message is obviously not helpful at all in this case.

The solution is to wrap my call in in the following:

using (var scope = new TransactionScope(TransactionScopeOption.Surpress))
{
    // execute DBMS_AQADM.START_QUEUE code here
    scope.Complete();
}

This causes the call to DBMS_AQADM.START_QUEUE to run outside of the ambient transaction.

Answer 2

This error comes from old OCI & prec-compiled code where an indicator variable was required to be set to indicate a null return for the field. When there is no indicator variable declared, this error is triggered if a null value is encountered. Obviously, some older code is still layered under the calls you made.

In other words, it is a data issue. I don't know where to start looking offhand.