Clear query cache

Author: bahusoid

src/NHibernate.Test/TestCase.cs

@@ -14,6 +14,8 @@
 using NUnit.Framework.Interfaces;
 using System.Text;
 using NHibernate.Driver;
+using NHibernate.SqlCommand;
+using NHibernate.SqlTypes;
 
 namespace NHibernate.Test
 {
@@ -297,13 +299,16 @@ public static void DropSchema(bool useStdOut, SchemaExport export, ISessionFacto
 				// As it seems Oracle can cache returned types for query for given connection.
 				// So exception can be thrown if two tests execute same query but with different types in result (like for Entity.Id int and Entity.Id Guid)
 				case OracleClientDriver oraSysData:
-					oraSysData.ClearPool(null);
-					break;
 				case OracleDataClientDriver oraUnmanaged:
-					oraUnmanaged.ClearPool(null);
-					break;
 				case OracleManagedDataClientDriver oraManaged:
-					oraManaged.ClearPool(null);
+					using (var con = sfi.ConnectionProvider.GetConnection())
+					using (var cmd = con.CreateCommand())
+					{
+						cmd.CommandText = "alter system flush shared_pool;";
+						cmd.Connection = con;
+						cmd.ExecuteNonQuery();
+					}
+
 					break;
 
 				// Firebird will pool each connection created during the test and will marked as used any table