Method onData

src/Client/ClientBase.cpp:576–631

void ClientBase::onData(Block & block, ASTPtr parsed_query)
{
    if (block.empty())
        return;

    processed_rows_from_blocks += block.rows();
    /// Even if all blocks are empty, we still need to initialize the output stream to write empty resultset.
    initOutputFormat(block, parsed_query);

    /// The header block containing zero rows was used to initialize
    /// output_format, do not output it.
    /// Also do not output too much data if we're fuzzing.
    if (block.rows() == 0 || (query_fuzzer_runs != 0 && processed_rows_from_blocks >= 100))
        return;

    try
    {
        output_format->write(materializeBlock(
            block,
            !output_format->supportsSpecialSerializationKinds()));
        written_first_block = true;
    }
    catch (const NetException &)
    {
        throw;
    }
    catch (const ErrnoException &)
    {
        throw;
    }
    catch (const Exception &)
    {
        //this is a bad catch. It catches too much cases unrelated to LocalFormatError
        /// Catch client errors like NO_ROW_DELIMITER
        throw LocalFormatError(getCurrentExceptionMessageAndPattern(print_stack_trace), getCurrentExceptionCode());
    }

    /// Received data block is immediately displayed to the user.
    output_format->flush();

    /// Restore progress bar and progress table after data block.
    if (need_render_progress && tty_buf)
    {
        if (select_into_file && !select_into_file_and_stdout)
            error_stream << "\r";
        std::unique_lock lock(tty_mutex);
        progress_indication.writeProgress(*tty_buf, lock);
    }
    if (need_render_progress_table && tty_buf && !cancelled)
    {
        if (!need_render_progress && select_into_file && !select_into_file_and_stdout)
            error_stream << "\r";
        std::unique_lock lock(tty_mutex);
        progress_table.writeTable(*tty_buf, lock, progress_table_toggle_on.load(), progress_table_toggle_enabled, false);
    }
}