Method resolveJoin

src/Analyzer/Resolve/QueryAnalyzer.cpp:5143–5421

Resolve join node in scope

/// Resolve join node in scope
void QueryAnalyzer::resolveJoin(QueryTreeNodePtr & join_node, IdentifierResolveScope & scope, QueryExpressionsAliasVisitor & expressions_visitor)
{
    checkStackSize();

    auto & join_node_typed = join_node->as<JoinNode &>();

    resolveQueryJoinTreeNode(join_node_typed.getLeftTableExpression(), scope, expressions_visitor);
    validateJoinTableExpressionWithoutAlias(join_node, join_node_typed.getLeftTableExpression(), scope);

    resolveQueryJoinTreeNode(join_node_typed.getRightTableExpression(), scope, expressions_visitor);
    validateJoinTableExpressionWithoutAlias(join_node, join_node_typed.getRightTableExpression(), scope);

    if (isCorrelatedQueryOrUnionNode(join_node_typed.getLeftTableExpression()))
        throw Exception(ErrorCodes::NOT_IMPLEMENTED,
            "Correlated subqueries are not supported in JOINs yet, but found in expression: {}",
            join_node_typed.getLeftTableExpression()->formatASTForErrorMessage());

    if (isCorrelatedQueryOrUnionNode(join_node_typed.getRightTableExpression()))
        throw Exception(ErrorCodes::NOT_IMPLEMENTED,
            "Correlated subqueries are not supported in JOINs yet, but found in expression: {}",
            join_node_typed.getRightTableExpression()->formatASTForErrorMessage());

    if (!join_node_typed.getLeftTableExpression()->hasAlias() && !join_node_typed.getRightTableExpression()->hasAlias())
        checkDuplicateTableNamesOrAliasForPasteJoin(join_node_typed, scope);

    if (join_node_typed.isNaturalJoin())
    {
        /// Synthesize a USING expression from the intersection of left and right column names.
        Names left_cols;
        NameSet right_cols;

        if (!getOrderedColumnsFromTableExpression(join_node_typed.getLeftTableExpression(), left_cols))
            throw Exception(ErrorCodes::NOT_IMPLEMENTED,
                "NATURAL JOIN: cannot determine columns of left table expression in {}",
                join_node_typed.formatASTForErrorMessage());

        if (!getColumnsFromTableExpression(join_node_typed.getRightTableExpression(), right_cols))
            throw Exception(ErrorCodes::NOT_IMPLEMENTED,
                "NATURAL JOIN: cannot determine columns of right table expression in {}",
                join_node_typed.formatASTForErrorMessage());

        QueryTreeNodes using_nodes;
        NameSet seen;
        for (const auto & col_name : left_cols)
        {
            /// Skip sub-columns (e.g. name.size) — NATURAL JOIN only matches top-level columns.
            if (col_name.find('.') != std::string::npos)
                continue;

            if (right_cols.contains(col_name) && !seen.contains(col_name))
            {
                seen.insert(col_name);
                using_nodes.push_back(std::make_shared<IdentifierNode>(Identifier(col_name)));
            }
        }

        if (using_nodes.empty())
        {