Function explainStep

src/Processors/QueryPlan/QueryPlan.cpp:274–330

}

static void explainStep(const IQueryPlanStep & step, JSONBuilder::JSONMap & map, const ExplainPlanOptions & options)
{
    map.add("Node Type", step.getName());
    map.add("Node Id", step.getUniqID());

    if (options.description)
    {
        const auto & description = step.getStepDescription();
        if (!description.empty())
            map.add("Description", description);
    }

    const auto dump_column = [](JSONBuilder::JSONArray & header_array, const ColumnWithTypeAndName & column)
    {
        auto column_map = std::make_unique<JSONBuilder::JSONMap>();
        column_map->add("Name", column.name);
        if (column.type)
            column_map->add("Type", column.type->getName());
        header_array.add(std::move(column_map));
    };

    if (options.header && step.hasOutputHeader())
    {
        auto header_array = std::make_unique<JSONBuilder::JSONArray>();

        for (const auto & output_column : *step.getOutputHeader())
            dump_column(*header_array, output_column);

        map.add("Header", std::move(header_array));
    }

    if (options.input_headers && !step.getInputHeaders().empty())
    {
        auto input_headers_array = std::make_unique<JSONBuilder::JSONArray>();

        for (const auto & input_header : step.getInputHeaders())
        {
            auto header_array = std::make_unique<JSONBuilder::JSONArray>();

            for (const auto & input_column : *input_header)
                dump_column(*header_array, input_column);

            input_headers_array->add(std::move(header_array));
        }

        map.add("Input Headers", std::move(input_headers_array));
    }

    if (options.actions)
        step.describeActions(map);

    if (options.indexes)
        step.describeIndexes(map);

    if (options.projections)
        step.describeProjections(map);
}