protected override async Task <int> DoUpdateRowsAsync(object id, IPersistentCollection collection, ISessionImplementor session, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            if (ArrayHelper.IsAllFalse(elementColumnIsSettable))
            {
                return(0);
            }

            try
            {
                DbCommand    st          = null;
                IExpectation expectation = Expectations.AppropriateExpectation(UpdateCheckStyle);
                //bool callable = UpdateCallable;
                bool        useBatch = expectation.CanBeBatched;
                IEnumerable entries  = collection.Entries(this);
                int         i        = 0;
                int         count    = 0;
                foreach (object entry in entries)
                {
                    if (await(collection.NeedsUpdatingAsync(entry, i, ElementType, cancellationToken)).ConfigureAwait(false))
                    {
                        int offset = 0;
                        if (useBatch)
                        {
                            if (st == null)
                            {
                                st =
                                    await(session.Batcher.PrepareBatchCommandAsync(SqlUpdateRowString.CommandType, SqlUpdateRowString.Text,
                                                                                   SqlUpdateRowString.ParameterTypes, cancellationToken)).ConfigureAwait(false);
                            }
                        }
                        else
                        {
                            st =
                                await(session.Batcher.PrepareCommandAsync(SqlUpdateRowString.CommandType, SqlUpdateRowString.Text,
                                                                          SqlUpdateRowString.ParameterTypes, cancellationToken)).ConfigureAwait(false);
                        }

                        try
                        {
                            //offset += expectation.Prepare(st, Factory.ConnectionProvider.Driver);

                            int loc = await(WriteElementAsync(st, collection.GetElement(entry), offset, session, cancellationToken)).ConfigureAwait(false);
                            if (hasIdentifier)
                            {
                                await(WriteIdentifierAsync(st, collection.GetIdentifier(entry, i), loc, session, cancellationToken)).ConfigureAwait(false);
                            }
                            else
                            {
                                loc = await(WriteKeyAsync(st, id, loc, session, cancellationToken)).ConfigureAwait(false);
                                if (HasIndex && !indexContainsFormula)
                                {
                                    await(WriteIndexToWhereAsync(st, collection.GetIndex(entry, i, this), loc, session, cancellationToken)).ConfigureAwait(false);
                                }
                                else
                                {
                                    await(WriteElementToWhereAsync(st, collection.GetSnapshotElement(entry, i), loc, session, cancellationToken)).ConfigureAwait(false);
                                }
                            }

                            if (useBatch)
                            {
                                await(session.Batcher.AddToBatchAsync(expectation, cancellationToken)).ConfigureAwait(false);
                            }
                            else
                            {
                                expectation.VerifyOutcomeNonBatched(await(session.Batcher.ExecuteNonQueryAsync(st, cancellationToken)).ConfigureAwait(false), st);
                            }
                        }

                        catch (OperationCanceledException) { throw; }
                        catch (Exception e)
                        {
                            if (useBatch)
                            {
                                session.Batcher.AbortBatch(e);
                            }
                            throw;
                        }
                        finally
                        {
                            if (!useBatch)
                            {
                                session.Batcher.CloseCommand(st, null);
                            }
                        }
                        count++;
                    }
                    i++;
                }
                return(count);
            }
            catch (DbException sqle)
            {
                throw ADOExceptionHelper.Convert(SQLExceptionConverter, sqle,
                                                 "could not update collection rows: " + MessageHelper.CollectionInfoString(this, collection, id, session),
                                                 SqlUpdateRowString.Text);
            }
        }
        protected override async Task <int> DoUpdateRowsAsync(object id, IPersistentCollection collection, ISessionImplementor session, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();
            // we finish all the "removes" first to take care of possible unique
            // constraints and so that we can take better advantage of batching
            try
            {
                const int offset = 0;
                int       count  = 0;

                if (RowDeleteEnabled)
                {
                    IExpectation   deleteExpectation = Expectations.AppropriateExpectation(DeleteCheckStyle);
                    bool           useBatch          = deleteExpectation.CanBeBatched;
                    SqlCommandInfo sql = SqlDeleteRowString;
                    // update removed rows fks to null
                    int         i       = 0;
                    IEnumerable entries = collection.Entries(this);

                    foreach (object entry in entries)
                    {
                        if (await(collection.NeedsUpdatingAsync(entry, i, ElementType, cancellationToken)).ConfigureAwait(false))
                        {
                            DbCommand st;
                            // will still be issued when it used to be null
                            if (useBatch)
                            {
                                st = await(session.Batcher.PrepareBatchCommandAsync(SqlDeleteRowString.CommandType, sql.Text,
                                                                                    SqlDeleteRowString.ParameterTypes, cancellationToken)).ConfigureAwait(false);
                            }
                            else
                            {
                                st = await(session.Batcher.PrepareCommandAsync(SqlDeleteRowString.CommandType, sql.Text,
                                                                               SqlDeleteRowString.ParameterTypes, cancellationToken)).ConfigureAwait(false);
                            }

                            try
                            {
                                int loc = await(WriteKeyAsync(st, id, offset, session, cancellationToken)).ConfigureAwait(false);
                                // No columnNullness handling: the element is the entity key and should not contain null
                                // values.
                                await(WriteElementToWhereAsync(st, collection.GetSnapshotElement(entry, i), null, loc, session, cancellationToken)).ConfigureAwait(false);
                                if (useBatch)
                                {
                                    await(session.Batcher.AddToBatchAsync(deleteExpectation, cancellationToken)).ConfigureAwait(false);
                                }
                                else
                                {
                                    deleteExpectation.VerifyOutcomeNonBatched(await(session.Batcher.ExecuteNonQueryAsync(st, cancellationToken)).ConfigureAwait(false), st);
                                }
                            }
                            catch (OperationCanceledException) { throw; }
                            catch (Exception e)
                            {
                                if (useBatch)
                                {
                                    session.Batcher.AbortBatch(e);
                                }
                                throw;
                            }
                            finally
                            {
                                if (!useBatch && st != null)
                                {
                                    session.Batcher.CloseCommand(st, null);
                                }
                            }
                            count++;
                        }
                        i++;
                    }
                }

                if (RowInsertEnabled)
                {
                    IExpectation insertExpectation = Expectations.AppropriateExpectation(InsertCheckStyle);
                    //bool callable = InsertCallable;
                    bool           useBatch = insertExpectation.CanBeBatched;
                    SqlCommandInfo sql      = SqlInsertRowString;

                    // now update all changed or added rows fks
                    int         i       = 0;
                    IEnumerable entries = collection.Entries(this);
                    foreach (object entry in entries)
                    {
                        if (await(collection.NeedsUpdatingAsync(entry, i, ElementType, cancellationToken)).ConfigureAwait(false))
                        {
                            DbCommand st;
                            if (useBatch)
                            {
                                st = await(session.Batcher.PrepareBatchCommandAsync(SqlInsertRowString.CommandType, sql.Text,
                                                                                    SqlInsertRowString.ParameterTypes, cancellationToken)).ConfigureAwait(false);
                            }
                            else
                            {
                                st = await(session.Batcher.PrepareCommandAsync(SqlInsertRowString.CommandType, sql.Text,
                                                                               SqlInsertRowString.ParameterTypes, cancellationToken)).ConfigureAwait(false);
                            }

                            try
                            {
                                //offset += insertExpectation.Prepare(st, Factory.ConnectionProvider.Driver);
                                int loc = await(WriteKeyAsync(st, id, offset, session, cancellationToken)).ConfigureAwait(false);
                                if (HasIndex && !indexContainsFormula)
                                {
                                    loc = await(WriteIndexToWhereAsync(st, collection.GetIndex(entry, i, this), loc, session, cancellationToken)).ConfigureAwait(false);
                                }
                                // No columnNullness handling: the element is the entity key and should not contain null
                                // values.
                                await(WriteElementToWhereAsync(st, collection.GetElement(entry), null, loc, session, cancellationToken)).ConfigureAwait(false);
                                if (useBatch)
                                {
                                    await(session.Batcher.AddToBatchAsync(insertExpectation, cancellationToken)).ConfigureAwait(false);
                                }
                                else
                                {
                                    insertExpectation.VerifyOutcomeNonBatched(await(session.Batcher.ExecuteNonQueryAsync(st, cancellationToken)).ConfigureAwait(false), st);
                                }
                            }
                            catch (OperationCanceledException) { throw; }
                            catch (Exception e)
                            {
                                if (useBatch)
                                {
                                    session.Batcher.AbortBatch(e);
                                }
                                throw;
                            }
                            finally
                            {
                                if (!useBatch && st != null)
                                {
                                    session.Batcher.CloseCommand(st, null);
                                }
                            }
                            count++;
                        }
                        i++;
                    }
                }
                return(count);
            }
            catch (DbException sqle)
            {
                throw ADOExceptionHelper.Convert(SQLExceptionConverter, sqle, "could not update collection rows: " + MessageHelper.CollectionInfoString(this, collection, id, session));
            }
        }