Add ExpressionDAG [Part 4].

src/Interpreters/ExpressionActions.cpp

@@ -1251,7 +1251,7 @@ void ExpressionActionsChain::addStep()
         throw Exception("Cannot add action to empty ExpressionActionsChain", ErrorCodes::LOGICAL_ERROR);
 
     ColumnsWithTypeAndName columns = steps.back()->getResultColumns();
-    steps.push_back(std::make_unique<ExpressionActionsStep>(std::make_shared<ExpressionActions>(columns, context)));
+    steps.push_back(std::make_unique<ExpressionActionsStep>(std::make_shared<ActionsDAG>(columns)));
 }
 
 void ExpressionActionsChain::finalize()
@@ -1398,12 +1398,17 @@ void ExpressionActionsChain::JoinStep::finalize(const Names & required_output_)
     std::swap(result_columns, new_result_columns);
 }
 
-ExpressionActionsPtr & ExpressionActionsChain::Step::actions()
+ActionsDAGPtr & ExpressionActionsChain::Step::actions()
 {
-    return typeid_cast<ExpressionActionsStep *>(this)->actions;
+    return typeid_cast<ExpressionActionsStep *>(this)->actions_dag;
 }
 
-const ExpressionActionsPtr & ExpressionActionsChain::Step::actions() const
+const ActionsDAGPtr & ExpressionActionsChain::Step::actions() const
+{
+    return typeid_cast<const ExpressionActionsStep *>(this)->actions_dag;
+}
+
+ExpressionActionsPtr ExpressionActionsChain::Step::getExpression() const
 {
     return typeid_cast<const ExpressionActionsStep *>(this)->actions;
 }
@@ -1420,13 +1425,18 @@ ActionsDAG::ActionsDAG(const ColumnsWithTypeAndName & inputs)
         addInput(input.name, input.type);
 }
 
-ActionsDAG::Node & ActionsDAG::addNode(Node node)
+ActionsDAG::Node & ActionsDAG::addNode(Node node, bool can_replace)
 {
-    if (index.count(node.result_name) != 0)
+    auto it = index.find(node.result_name);
+    if (it != index.end() && !can_replace)
         throw Exception("Column '" + node.result_name + "' already exists", ErrorCodes::DUPLICATE_COLUMN);
 
     auto & res = nodes.emplace_back(std::move(node));
     index[res.result_name] = &res;
+
+    if (it != index.end())
+        it->second->renaming_parent = &res;
+
     return res;
 }
 
@@ -1460,7 +1470,7 @@ const ActionsDAG::Node & ActionsDAG::addColumn(ColumnWithTypeAndName column)
     return addNode(std::move(node));
 }
 
-const ActionsDAG::Node & ActionsDAG::addAlias(const std::string & name, std::string alias)
+const ActionsDAG::Node & ActionsDAG::addAlias(const std::string & name, std::string alias, bool can_replace)
 {
     auto & child = getNode(name);
 
@@ -1472,7 +1482,7 @@ const ActionsDAG::Node & ActionsDAG::addAlias(const std::string & name, std::str
     node.allow_constant_folding = child.allow_constant_folding;
     node.children.emplace_back(&child);
 
-    return addNode(std::move(node));
+    return addNode(std::move(node), can_replace);
 }
 
 const ActionsDAG::Node & ActionsDAG::addArrayJoin(const std::string & source_name, std::string result_name)
@@ -1591,8 +1601,9 @@ const ActionsDAG::Node & ActionsDAG::addFunction(
 ColumnsWithTypeAndName ActionsDAG::getResultColumns() const
 {
     ColumnsWithTypeAndName result;
-    result.reserve(nodes.size());
+    result.reserve(index.size());
     for (const auto & node : nodes)
+        if (!node.renaming_parent)
             result.emplace_back(node.column, node.result_type, node.result_name);
 
     return result;
@@ -1602,11 +1613,23 @@ NamesAndTypesList ActionsDAG::getNamesAndTypesList() const
 {
     NamesAndTypesList result;
     for (const auto & node : nodes)
+        if (!node.renaming_parent)
             result.emplace_back(node.result_name, node.result_type);
 
     return result;
 }
 
+Names ActionsDAG::getNames() const
+{
+    Names names;
+    names.reserve(index.size());
+    for (const auto & node : nodes)
+        if (!node.renaming_parent)
+            names.emplace_back(node.result_name);
+
+    return names;
+}
+
 std::string ActionsDAG::dumpNames() const
 {
     WriteBufferFromOwnString out;
@@ -1625,7 +1648,9 @@ ExpressionActionsPtr ActionsDAG::buildExpressions(const Context & context)
     {
         Node * node = nullptr;
         size_t num_created_children = 0;
+        size_t num_expected_children = 0;
         std::vector<Node *> parents;
+        Node * renamed_child = nullptr;
     };
 
     std::vector<Data> data(nodes.size());
@@ -1643,13 +1668,38 @@ ExpressionActionsPtr ActionsDAG::buildExpressions(const Context & context)
 
     for (auto & node : nodes)
     {
+        data[reverse_index[&node]].num_expected_children += node.children.size();
+
         for (const auto & child : node.children)
             data[reverse_index[child]].parents.emplace_back(&node);
 
-        if (node.children.empty())
+        if (node.renaming_parent)
+        {
+
+            auto & cur = data[reverse_index[node.renaming_parent]];
+            cur.renamed_child = &node;
+            cur.num_expected_children += 1;
+        }
+    }
+
+    for (auto & node : nodes)
+    {
+        if (node.children.empty() && data[reverse_index[&node]].renamed_child == nullptr)
             ready_nodes.emplace(&node);
     }
 
+    auto update_parent = [&](Node * parent)
+    {
+        auto & cur = data[reverse_index[parent]];
+        ++cur.num_created_children;
+
+        if (cur.num_created_children == cur.num_expected_children)
+        {
+            auto & push_stack = parent->type == Type::ARRAY_JOIN ? ready_array_joins : ready_nodes;
+            push_stack.push(parent);
+        }
+    };
+
     auto expressions = std::make_shared<ExpressionActions>(NamesAndTypesList(), context);
 
     while (!ready_nodes.empty() || !ready_array_joins.empty())
@@ -1662,6 +1712,8 @@ ExpressionActionsPtr ActionsDAG::buildExpressions(const Context & context)
         for (const auto & child : node->children)
             argument_names.emplace_back(child->result_name);
 
+        auto & cur = data[reverse_index[node]];
+
         switch (node->type)
         {
             case Type::INPUT:
@@ -1671,7 +1723,7 @@ ExpressionActionsPtr ActionsDAG::buildExpressions(const Context & context)
                 expressions->add(ExpressionAction::addColumn({node->column, node->result_type, node->result_name}));
                 break;
             case Type::ALIAS:
-                expressions->add(ExpressionAction::copyColumn(argument_names.at(0), node->result_name));
+                expressions->add(ExpressionAction::copyColumn(argument_names.at(0), node->result_name, cur.renamed_child != nullptr));
                 break;
             case Type::ARRAY_JOIN:
                 expressions->add(ExpressionAction::arrayJoin(argument_names.at(0), node->result_name));
@@ -1681,17 +1733,11 @@ ExpressionActionsPtr ActionsDAG::buildExpressions(const Context & context)
                 break;
         }
 
-        for (const auto & parent : data[reverse_index[node]].parents)
+        for (const auto & parent : cur.parents)
-        {
+            update_parent(parent);
-            auto & cur = data[reverse_index[parent]];
-            ++cur.num_created_children;
 
-            if (parent->children.size() == cur.num_created_children)
+        if (node->renaming_parent)
-            {
+            update_parent(node->renaming_parent);
-                auto & push_stack = parent->type == Type::ARRAY_JOIN ? ready_array_joins : ready_nodes;
-                push_stack.push(parent);
-            }
-        }
     }
 
     return expressions;

src/Interpreters/ExpressionActions.h

@@ -160,6 +160,8 @@ public:
     struct Node
     {
         std::vector<Node *> children;
+        /// This field is filled if current node is replaced by existing node with the same name.
+        Node * renaming_parent = nullptr;
 
         Type type;
 
@@ -192,16 +194,16 @@ public:
     ActionsDAG(const NamesAndTypesList & inputs);
     ActionsDAG(const ColumnsWithTypeAndName & inputs);
 
-    const std::list<Node> & getNodes() const;
     const Index & getIndex() const { return index; }
 
     ColumnsWithTypeAndName getResultColumns() const;
     NamesAndTypesList getNamesAndTypesList() const;
+    Names getNames() const;
     std::string dumpNames() const;
 
     const Node & addInput(std::string name, DataTypePtr type);
     const Node & addColumn(ColumnWithTypeAndName column);
-    const Node & addAlias(const std::string & name, std::string alias);
+    const Node & addAlias(const std::string & name, std::string alias, bool can_replace);
     const Node & addArrayJoin(const std::string & source_name, std::string result_name);
     const Node & addFunction(
             const FunctionOverloadResolverPtr & function,
@@ -212,10 +214,12 @@ public:
     ExpressionActionsPtr buildExpressions(const Context & context);
 
 private:
-    Node & addNode(Node node);
+    Node & addNode(Node node, bool can_replace = false);
     Node & getNode(const std::string & name);
 };
 
+using ActionsDAGPtr = std::shared_ptr<ActionsDAG>;
+
 /** Contains a sequence of actions on the block.
   */
 class ExpressionActions
@@ -363,17 +367,19 @@ struct ExpressionActionsChain
         virtual std::string dump() const = 0;
 
         /// Only for ExpressionActionsStep
-        ExpressionActionsPtr & actions();
+        ActionsDAGPtr & actions();
-        const ExpressionActionsPtr & actions() const;
+        const ActionsDAGPtr & actions() const;
+        ExpressionActionsPtr getExpression() const;
     };
 
     struct ExpressionActionsStep : public Step
     {
+        ActionsDAGPtr actions_dag;
         ExpressionActionsPtr actions;
 
-        explicit ExpressionActionsStep(ExpressionActionsPtr actions_, Names required_output_ = Names())
+        explicit ExpressionActionsStep(ActionsDAGPtr actions_, Names required_output_ = Names())
             : Step(std::move(required_output_))
-            , actions(std::move(actions_))
+            , actions_dag(std::move(actions_))
         {
         }
 
@@ -458,7 +464,9 @@ struct ExpressionActionsChain
             throw Exception("Empty ExpressionActionsChain", ErrorCodes::LOGICAL_ERROR);
         }
 
-        return steps.back()->actions();
+        auto * step = typeid_cast<ExpressionActionsStep *>(&steps.back());
+        step->actions = step->actions_dag->buildExpressions(context);
+        return step->actions;
     }
 
     Step & getLastStep()
@@ -472,7 +480,7 @@ struct ExpressionActionsChain
     Step & lastStep(const NamesAndTypesList & columns)
     {
         if (steps.empty())
-            steps.emplace_back(std::make_unique<ExpressionActionsStep>(std::make_shared<ExpressionActions>(columns, context)));
+            steps.emplace_back(std::make_unique<ExpressionActionsStep>(std::make_shared<ActionsDAG>(columns)));
         return *steps.back();
     }
 

src/Interpreters/ExpressionAnalyzer.cpp

@@ -472,8 +472,8 @@ ArrayJoinActionPtr SelectQueryExpressionAnalyzer::appendArrayJoin(ExpressionActi
 
     getRootActions(array_join_expression_list, only_types, step.actions());
 
-    before_array_join = chain.getLastActions();
     auto array_join = addMultipleArrayJoinAction(step.actions(), is_array_join_left);
+    before_array_join = chain.getLastActions();
 
     chain.steps.push_back(std::make_unique<ExpressionActionsChain::ArrayJoinStep>(
             array_join, step.getResultColumns()));
@@ -615,13 +615,14 @@ JoinPtr SelectQueryExpressionAnalyzer::makeTableJoin(const ASTTablesInSelectQuer
     return subquery_for_join.join;
 }
 
-bool SelectQueryExpressionAnalyzer::appendPrewhere(
+ExpressionActionsPtr SelectQueryExpressionAnalyzer::appendPrewhere(
     ExpressionActionsChain & chain, bool only_types, const Names & additional_required_columns)
 {
     const auto * select_query = getSelectQuery();
+    ExpressionActionsPtr prewhere_actions;
 
     if (!select_query->prewhere())
-        return false;
+        return prewhere_actions;
 
     auto & step = chain.lastStep(sourceColumns());
     getRootActions(select_query->prewhere(), only_types, step.actions());
@@ -629,15 +630,16 @@ bool SelectQueryExpressionAnalyzer::appendPrewhere(
     step.required_output.push_back(prewhere_column_name);
     step.can_remove_required_output.push_back(true);
 
-    auto filter_type = step.actions()->getSampleBlock().getByName(prewhere_column_name).type;
+    auto filter_type = step.actions()->getIndex().find(prewhere_column_name)->second->result_type;
     if (!filter_type->canBeUsedInBooleanContext())
         throw Exception("Invalid type for filter in PREWHERE: " + filter_type->getName(),
                         ErrorCodes::ILLEGAL_TYPE_OF_COLUMN_FOR_FILTER);
 
     {
         /// Remove unused source_columns from prewhere actions.
-        auto tmp_actions = std::make_shared<ExpressionActions>(sourceColumns(), context);
+        auto tmp_actions_dag = std::make_shared<ActionsDAG>(sourceColumns());
-        getRootActions(select_query->prewhere(), only_types, tmp_actions);
+        getRootActions(select_query->prewhere(), only_types, tmp_actions_dag);
+        auto tmp_actions = tmp_actions_dag->buildExpressions(context);
         tmp_actions->finalize({prewhere_column_name});
         auto required_columns = tmp_actions->getRequiredColumns();
         NameSet required_source_columns(required_columns.begin(), required_columns.end());
@@ -653,7 +655,7 @@ bool SelectQueryExpressionAnalyzer::appendPrewhere(
             }
         }
 
-        auto names = step.actions()->getSampleBlock().getNames();
+        auto names = step.actions()->getNames();
         NameSet name_set(names.begin(), names.end());
 
         for (const auto & column : sourceColumns())
@@ -661,7 +663,8 @@ bool SelectQueryExpressionAnalyzer::appendPrewhere(
                 name_set.erase(column.name);
 
         Names required_output(name_set.begin(), name_set.end());
-        step.actions()->finalize(required_output);
+        prewhere_actions = chain.getLastActions();
+        prewhere_actions->finalize(required_output);
     }
 
     {
@@ -672,8 +675,8 @@ bool SelectQueryExpressionAnalyzer::appendPrewhere(
         /// 2. Store side columns which were calculated during prewhere actions execution if they are used.
         ///    Example: select F(A) prewhere F(A) > 0. F(A) can be saved from prewhere step.
         /// 3. Check if we can remove filter column at prewhere step. If we can, action will store single REMOVE_COLUMN.
-        ColumnsWithTypeAndName columns = step.actions()->getSampleBlock().getColumnsWithTypeAndName();
+        ColumnsWithTypeAndName columns = prewhere_actions->getSampleBlock().getColumnsWithTypeAndName();
-        auto required_columns = step.actions()->getRequiredColumns();
+        auto required_columns = prewhere_actions->getRequiredColumns();
         NameSet prewhere_input_names(required_columns.begin(), required_columns.end());
         NameSet unused_source_columns;
 
@@ -687,11 +690,13 @@ bool SelectQueryExpressionAnalyzer::appendPrewhere(
         }
 
         chain.steps.emplace_back(std::make_unique<ExpressionActionsChain::ExpressionActionsStep>(
-                std::make_shared<ExpressionActions>(std::move(columns), context)));
+                std::make_shared<ActionsDAG>(std::move(columns))));
         chain.steps.back()->additional_input = std::move(unused_source_columns);
+        chain.getLastActions();
+        chain.addStep();
     }
 
-    return true;
+    return prewhere_actions;
 }
 
 void SelectQueryExpressionAnalyzer::appendPreliminaryFilter(ExpressionActionsChain & chain, ExpressionActionsPtr actions, String column_name)
@@ -699,7 +704,8 @@ void SelectQueryExpressionAnalyzer::appendPreliminaryFilter(ExpressionActionsCha
     ExpressionActionsChain::Step & step = chain.lastStep(sourceColumns());
 
     // FIXME: assert(filter_info);
-    step.actions() = std::move(actions);
+    auto * expression_step = typeid_cast<ExpressionActionsChain::ExpressionActionsStep *>(&step);
+    expression_step->actions = std::move(actions);
     step.required_output.push_back(std::move(column_name));
     step.can_remove_required_output = {true};
 
@@ -721,7 +727,7 @@ bool SelectQueryExpressionAnalyzer::appendWhere(ExpressionActionsChain & chain,
 
     getRootActions(select_query->where(), only_types, step.actions());
 
-    auto filter_type = step.actions()->getSampleBlock().getByName(where_column_name).type;
+    auto filter_type = step.actions()->getIndex().find(where_column_name)->second->result_type;
     if (!filter_type->canBeUsedInBooleanContext())
         throw Exception("Invalid type for filter in WHERE: " + filter_type->getName(),
                         ErrorCodes::ILLEGAL_TYPE_OF_COLUMN_FOR_FILTER);
@@ -750,8 +756,9 @@ bool SelectQueryExpressionAnalyzer::appendGroupBy(ExpressionActionsChain & chain
     {
         for (auto & child : asts)
         {
-            group_by_elements_actions.emplace_back(std::make_shared<ExpressionActions>(columns_after_join, context));
+            auto actions_dag = std::make_shared<ActionsDAG>(columns_after_join);
-            getRootActions(child, only_types, group_by_elements_actions.back());
+            getRootActions(child, only_types, actions_dag);
+            group_by_elements_actions.emplace_back(actions_dag->buildExpressions(context));
         }
     }
 
@@ -838,8 +845,9 @@ bool SelectQueryExpressionAnalyzer::appendOrderBy(ExpressionActionsChain & chain
     {
         for (auto & child : select_query->orderBy()->children)
         {
-            order_by_elements_actions.emplace_back(std::make_shared<ExpressionActions>(columns_after_join, context));
+            auto actions_dag = std::make_shared<ActionsDAG>(columns_after_join);
-            getRootActions(child, only_types, order_by_elements_actions.back());
+            getRootActions(child, only_types, actions_dag);
+            order_by_elements_actions.emplace_back(actions_dag->buildExpressions(context));
         }
     }
     return true;
@@ -919,7 +927,7 @@ void SelectQueryExpressionAnalyzer::appendProjectResult(ExpressionActionsChain &
         }
     }
 
-    step.actions()->add(ExpressionAction::project(result_columns));
+    chain.getLastActions()->add(ExpressionAction::project(result_columns));
 }
 
 
@@ -933,7 +941,7 @@ void ExpressionAnalyzer::appendExpression(ExpressionActionsChain & chain, const
 
 ExpressionActionsPtr ExpressionAnalyzer::getActions(bool add_aliases, bool project_result)
 {
-    ExpressionActionsPtr actions = std::make_shared<ExpressionActions>(aggregated_columns, context);
+    auto actions_dag = std::make_shared<ActionsDAG>(aggregated_columns);
     NamesWithAliases result_columns;
     Names result_names;
 
@@ -954,9 +962,11 @@ ExpressionActionsPtr ExpressionAnalyzer::getActions(bool add_aliases, bool proje
             alias = name;
         result_columns.emplace_back(name, alias);
         result_names.push_back(alias);
-        getRootActions(ast, false, actions);
+        getRootActions(ast, false, actions_dag);
     }
 
+    auto actions = actions_dag->buildExpressions(context);
+
     if (add_aliases)
     {
         if (project_result)
@@ -980,10 +990,10 @@ ExpressionActionsPtr ExpressionAnalyzer::getActions(bool add_aliases, bool proje
 
 ExpressionActionsPtr ExpressionAnalyzer::getConstActions()
 {
-    ExpressionActionsPtr actions = std::make_shared<ExpressionActions>(NamesAndTypesList(), context);
+    auto actions = std::make_shared<ActionsDAG>(NamesAndTypesList());
 
     getRootActions(query, true, actions, true);
-    return actions;
+    return actions->buildExpressions(context);
 }
 
 ExpressionActionsPtr SelectQueryExpressionAnalyzer::simpleSelectActions()
@@ -1064,10 +1074,9 @@ ExpressionAnalysisResult::ExpressionAnalysisResult(
             query_analyzer.appendPreliminaryFilter(chain, filter_info->actions, filter_info->column_name);
         }
 
-        if (query_analyzer.appendPrewhere(chain, !first_stage, additional_required_columns_after_prewhere))
+        if (auto actions = query_analyzer.appendPrewhere(chain, !first_stage, additional_required_columns_after_prewhere))
         {
-            prewhere_info = std::make_shared<PrewhereInfo>(
+            prewhere_info = std::make_shared<PrewhereInfo>(actions, query.prewhere()->getColumnName());
-                    chain.steps.front()->actions(), query.prewhere()->getColumnName());
 
             if (allowEarlyConstantFolding(*prewhere_info->prewhere_actions, settings))
             {
@@ -1081,7 +1090,6 @@ ExpressionAnalysisResult::ExpressionAnalysisResult(
                         prewhere_constant_filter_description = ConstantFilterDescription(*column_elem.column);
                 }
             }
-            chain.addStep();
         }
 
         array_join = query_analyzer.appendArrayJoin(chain, before_array_join, only_types || !first_stage);

src/Interpreters/ExpressionAnalyzer.h

@@ -319,7 +319,7 @@ private:
     void appendPreliminaryFilter(ExpressionActionsChain & chain, ExpressionActionsPtr actions, String column_name);
     /// remove_filter is set in ExpressionActionsChain::finalize();
     /// Columns in `additional_required_columns` will not be removed (they can be used for e.g. sampling or FINAL modifier).
-    bool appendPrewhere(ExpressionActionsChain & chain, bool only_types, const Names & additional_required_columns);
+    ExpressionActionsPtr appendPrewhere(ExpressionActionsChain & chain, bool only_types, const Names & additional_required_columns);
     bool appendWhere(ExpressionActionsChain & chain, bool only_types);
     bool appendGroupBy(ExpressionActionsChain & chain, bool only_types, bool optimize_aggregation_in_order, ManyExpressionActions &);
     void appendAggregateFunctionsArguments(ExpressionActionsChain & chain, bool only_types);

src/Interpreters/MutationsInterpreter.cpp

@@ -612,8 +612,8 @@ ASTPtr MutationsInterpreter::prepareInterpreterSelectQuery(std::vector<Stage> &
 
             for (const auto & kv : stage.column_to_updated)
             {
-                actions_chain.getLastActions()->add(ExpressionAction::copyColumn(
+                actions_chain.getLastStep().actions()->addAlias(
-                        kv.second->getColumnName(), kv.first, /* can_replace = */ true));
+                        kv.second->getColumnName(), kv.first, /* can_replace = */ true);
             }
         }
 
@@ -624,7 +624,7 @@ ASTPtr MutationsInterpreter::prepareInterpreterSelectQuery(std::vector<Stage> &
         actions_chain.finalize();
 
         /// Propagate information about columns needed as input.
-        for (const auto & column : actions_chain.steps.front()->actions()->getRequiredColumnsWithTypes())
+        for (const auto & column : actions_chain.steps.front()->getRequiredColumns())
             prepared_stages[i - 1].output_columns.insert(column.name);
     }
 
@@ -670,7 +670,7 @@ void MutationsInterpreter::addStreamsForLaterStages(const std::vector<Stage> & p
                 /// Execute DELETEs.
                 pipeline.addSimpleTransform([&](const Block & header)
                 {
-                    return std::make_shared<FilterTransform>(header, step->actions(), stage.filter_column_names[i], false);
+                    return std::make_shared<FilterTransform>(header, step->getExpression(), stage.filter_column_names[i], false);
                 });
             }
             else
@@ -678,7 +678,7 @@ void MutationsInterpreter::addStreamsForLaterStages(const std::vector<Stage> & p
                 /// Execute UPDATE or final projection.
                 pipeline.addSimpleTransform([&](const Block & header)
                 {
-                    return std::make_shared<ExpressionTransform>(header, step->actions());
+                    return std::make_shared<ExpressionTransform>(header, step->getExpression());
                 });
             }
         }