Method makeJoin

src/Interpreters/ExpressionAnalyzer.cpp:1253–1295

}

JoinPtr SelectQueryExpressionAnalyzer::makeJoin(
    const ASTTablesInSelectQueryElement & join_element,
    const ColumnsWithTypeAndName & left_columns,
    std::optional<ActionsDAG> & left_convert_actions)
{
    /// Two JOINs are not supported with the same subquery, but different USINGs.

    if (joined_plan)
        throw Exception(ErrorCodes::LOGICAL_ERROR, "Table join was already created for query");

    std::optional<ActionsDAG> right_convert_actions;

    const auto & analyzed_join = syntax->analyzed_join;

    if (auto storage = analyzed_join->getStorageJoin())
    {
        auto joined_block_actions = analyzed_join->createJoinedBlockActions(getContext(), getPreparedSets());
        NamesWithAliases required_columns_with_aliases = analyzed_join->getRequiredColumns(
            Block(joined_block_actions.getResultColumns()), joined_block_actions.getRequiredColumns().getNames());

        Names original_right_column_names;
        for (auto & pr : required_columns_with_aliases)
            original_right_column_names.push_back(pr.first);

        auto right_columns = storage->getRightSampleBlock().getColumnsWithTypeAndName();
        std::tie(left_convert_actions, right_convert_actions) = analyzed_join->createConvertingActions(left_columns, right_columns, getContext());
        return storage->getJoinLocked(analyzed_join, getContext(), original_right_column_names);
    }

    joined_plan = buildJoinedPlan(getContext(), getPreparedSets(), join_element, *analyzed_join, query_options);

    const ColumnsWithTypeAndName & right_columns = joined_plan->getCurrentHeader()->getColumnsWithTypeAndName();
    std::tie(left_convert_actions, right_convert_actions) = analyzed_join->createConvertingActions(left_columns, right_columns, getContext());
    if (right_convert_actions)
    {
        auto converting_step = std::make_unique<ExpressionStep>(joined_plan->getCurrentHeader(), std::move(*right_convert_actions));
        converting_step->setStepDescription("Convert joined columns");
        joined_plan->addStep(std::move(converting_step));
    }

    JoinPtr join = chooseJoinAlgorithm(analyzed_join, left_columns, joined_plan, getContext());
    return join;
}

ActionsAndProjectInputsFlagPtr SelectQueryExpressionAnalyzer::appendPrewhere(
    ExpressionActionsChain & chain, bool only_types)