问如何清除Oracle.ManagedDataAccess.Client表结构缓存

EN

public ActionResult<object> Try()
{
    OracleConnection conn = (OracleConnection)_context.Database.GetDbConnection();
    if (conn.State != ConnectionState.Open)
        conn.Open();
    var cmd = conn.CreateCommand();
    cmd.CommandText = "select * from mytable fetch first 1 rows only";

    var result = new List<string>();
    using (OracleDataReader reader = cmd.ExecuteReader())
    {
        while (reader.Read())
            result.Add(reader.GetName(0)+": "+reader.GetValue(0).ToString());
    }
    return string.Join(',',result);
}

create table mytable (f1 number(10), f2 varchar2(10));
insert into mytable values (32,'32');
grant select on mytable to myuser;

http://localhost/MyController/Try
// output is okay:
// F1: 32

alter table mytable add f3 varchar2(5) default ('f3') null;

http://localhost/MyController/Try

System.Exception
  HResult=0x80131500
  Message=Internal Error
  Source=Oracle.ManagedDataAccess
  StackTrace:
   at OracleInternal.TTC.TTCExecuteSql.ReceiveExecuteResponse(Accessor[]& defineAccessors, Accessor[] bindAccessors, Boolean bHasReturningParams, SQLMetaData& sqlMetaData, SqlStatementType statementType, Int64 noOfRowsFetchedLastTime, Int32 noOfRowsToFetch, Int32& noOfRowsFetched, Int64& queryId, Int32 longFetchSize, Int64 clientInitialLOBFetchSize, Int64 initialLOBFetchSize, Int64 initialJSONFetchSize, Int64[] scnFromExecution, Boolean bAllInputBinds, Int32 arrayBindCount, DataUnmarshaller& dataUnmarshaller, MarshalBindParameterValueHelper& marshalBindParamsHelper, Int64[]& rowsAffectedByArrayBind, Boolean bDefineDone, Boolean& bMoreThanOneRowAffectedByDmlWithRetClause, List`1& implicitRSList, Boolean bLOBArrayFetchRequired)
   at OracleInternal.ServiceObjects.OracleCommandImpl.ExecuteReader(String commandText, OracleParameterCollection paramColl, CommandType commandType, OracleConnectionImpl connectionImpl, OracleDataReaderImpl& rdrImpl, Int32 longFetchSize, Int64 clientInitialLOBFS, OracleDependencyImpl orclDependencyImpl, Int64[] scnForExecution, Int64[]& scnFromExecution, OracleParameterCollection& bindByPositionParamColl, Boolean& bBindParamPresent, Int64& internalInitialLOBFS, Int64 internalInitialJSONFS, OracleException& exceptionForArrayBindDML, OracleConnection connection, IEnumerable`1 adrianParsedStmt, Boolean isDescribeOnly, Boolean isFromEF)
   at Oracle.ManagedDataAccess.Client.OracleCommand.ExecuteReader(Boolean requery, Boolean fillRequest, CommandBehavior behavior)
   at Oracle.ManagedDataAccess.Client.OracleCommand.ExecuteReader()