Method generateOutput

src/Server/GRPCServer.cpp:1280–1385

    }

    void Call::generateOutput()
    {
        /// We add query_id and time_zone to the first result anyway.
        addQueryDetailsToResult();

        if (!io.pipeline.initialized() || io.pipeline.pushing())
            return;

        Block header;
        if (io.pipeline.pulling())
            header = io.pipeline.getHeader();

        if (output_compression_method != CompressionMethod::None)
            output.resize(DBMS_DEFAULT_BUFFER_SIZE); /// Must have enough space for compressed data.
        write_buffer = std::make_unique<WriteBufferFromVector<PODArray<char>>>(output);
        nested_write_buffer = static_cast<WriteBufferFromVector<PODArray<char>> *>(write_buffer.get());
        if (output_compression_method != CompressionMethod::None)
        {
            write_buffer = wrapWriteBufferWithCompressionMethod(std::move(write_buffer), output_compression_method, output_compression_level);
            compressing_write_buffer = write_buffer.get();
        }

        auto has_output = [&] { return (nested_write_buffer->position() != output.data()) || (compressing_write_buffer && compressing_write_buffer->offset()); };

        output_format_processor = query_context->getOutputFormat(output_format, *write_buffer, header);
        Stopwatch after_send_progress;

        /// Unless the input() function is used we are not going to receive input data anymore.
        if (!input_function_is_used)
            check_query_info_contains_cancel_only = true;

        if (io.pipeline.pulling())
        {
            auto executor = std::make_shared<PullingAsyncPipelineExecutor>(io.pipeline);
            io.pipeline.setConcurrencyControl(query_context->getSettingsRef()[Setting::use_concurrency_control]);
            auto check_for_cancel = [&]
            {
                if (isQueryCancelled())
                {
                    executor->cancel();
                    return false;
                }
                return true;
            };

            addOutputFormatToResult();
            addOutputColumnsNamesAndTypesToResult(header);

            Block block;
            while (check_for_cancel())
            {
                if (!executor->pull(block, interactive_delay / 1000))
                    break;

                throwIfFailedToSendResult();
                if (!check_for_cancel())
                    break;