Function buildFilterInfo

src/Planner/Utils.cpp:565–602

}

FilterDAGInfo buildFilterInfo(ASTPtr filter_expression,
        const QueryTreeNodePtr & table_expression,
        PlannerContextPtr & planner_context,
        NameSet table_expression_required_names_without_filter)
{
    const auto & query_context = planner_context->getQueryContext();

    /// If the filter expression is a standalone subquery (e.g. ROW POLICY
    /// USING (SELECT 1)), wrap it with notEquals(<subquery>, 0) so that
    /// buildQueryTree produces a FunctionNode at the top level instead of
    /// a bare QueryNode/UnionNode.  QueryAnalyzer::resolve() requires
    /// table_expression to be empty for top-level QUERY/UNION nodes;
    /// wrapping turns the subquery into a function argument that is
    /// resolved through the normal scalar-subquery evaluation path.
    /// We use notEquals(x, 0) rather than equals(1, x) to preserve
    /// boolean semantics: any non-zero value is truthy (e.g. USING (SELECT 2)
    /// should allow rows, not deny them).
    if (filter_expression->as<ASTSubquery>()
        || filter_expression->as<ASTSelectWithUnionQuery>())
    {
        filter_expression = makeASTFunction("notEquals",
            filter_expression,
            make_intrusive<ASTLiteral>(Field(UInt8(0))));
    }

    auto filter_query_tree = buildQueryTree(filter_expression, query_context);

    QueryAnalysisPass query_analysis_pass(table_expression);
    query_analysis_pass.run(filter_query_tree, query_context);

    /// Optimize logical expressions in the filter, e.g. convert OR-chains of
    /// equalities into IN (important for row policies that produce many
    /// permissive conditions like `x = 1 OR x = 2 OR ... OR x = N`).
    LogicalExpressionOptimizerPass logical_expression_optimizer_pass;
    logical_expression_optimizer_pass.run(filter_query_tree, query_context);

    return buildFilterInfo(std::move(filter_query_tree), table_expression, planner_context, std::move(table_expression_required_names_without_filter));
}

FilterDAGInfo buildFilterInfo(QueryTreeNodePtr filter_query_tree,
        const QueryTreeNodePtr & table_expression,