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Posted to commits@quickstep.apache.org by ji...@apache.org on 2017/01/30 00:47:46 UTC
incubator-quickstep git commit: Reduce the number of group-by
attributes by pulling tables up aggregations
Repository: incubator-quickstep
Updated Branches:
refs/heads/reduce-group-by-attrs [created] 04db5cd77
Reduce the number of group-by attributes by pulling tables up aggregations
Project: http://git-wip-us.apache.org/repos/asf/incubator-quickstep/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-quickstep/commit/04db5cd7
Tree: http://git-wip-us.apache.org/repos/asf/incubator-quickstep/tree/04db5cd7
Diff: http://git-wip-us.apache.org/repos/asf/incubator-quickstep/diff/04db5cd7
Branch: refs/heads/reduce-group-by-attrs
Commit: 04db5cd770472e9ca3ee02514727a2b9940ce1ca
Parents: 3210500
Author: Jianqiao Zhu <ji...@cs.wisc.edu>
Authored: Sun Jan 29 18:36:14 2017 -0600
Committer: Jianqiao Zhu <ji...@cs.wisc.edu>
Committed: Sun Jan 29 18:47:32 2017 -0600
----------------------------------------------------------------------
query_optimizer/CMakeLists.txt | 1 +
query_optimizer/Optimizer.cpp | 3 +-
query_optimizer/Optimizer.hpp | 2 -
query_optimizer/PhysicalGenerator.cpp | 2 +
query_optimizer/PhysicalGenerator.hpp | 11 +-
query_optimizer/cost_model/CMakeLists.txt | 1 +
.../cost_model/StarSchemaSimpleCostModel.cpp | 79 ++++++-
.../cost_model/StarSchemaSimpleCostModel.hpp | 21 ++
query_optimizer/rules/CMakeLists.txt | 23 ++
.../rules/ReduceGroupByAttributes.cpp | 211 +++++++++++++++++++
.../rules/ReduceGroupByAttributes.hpp | 143 +++++++++++++
query_optimizer/tests/OptimizerTest.cpp | 2 +-
12 files changed, 484 insertions(+), 15 deletions(-)
----------------------------------------------------------------------
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/CMakeLists.txt
----------------------------------------------------------------------
diff --git a/query_optimizer/CMakeLists.txt b/query_optimizer/CMakeLists.txt
index b6c794d..587288e 100644
--- a/query_optimizer/CMakeLists.txt
+++ b/query_optimizer/CMakeLists.txt
@@ -207,6 +207,7 @@ target_link_libraries(quickstep_queryoptimizer_PhysicalGenerator
quickstep_queryoptimizer_physical_Physical
quickstep_queryoptimizer_rules_AttachLIPFilters
quickstep_queryoptimizer_rules_PruneColumns
+ quickstep_queryoptimizer_rules_ReduceGroupByAttributes
quickstep_queryoptimizer_rules_StarSchemaHashJoinOrderOptimization
quickstep_queryoptimizer_rules_SwapProbeBuild
quickstep_queryoptimizer_strategy_Aggregate
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/Optimizer.cpp
----------------------------------------------------------------------
diff --git a/query_optimizer/Optimizer.cpp b/query_optimizer/Optimizer.cpp
index b14c938..1b91574 100644
--- a/query_optimizer/Optimizer.cpp
+++ b/query_optimizer/Optimizer.cpp
@@ -30,10 +30,11 @@ void Optimizer::generateQueryHandle(const ParseStatement &parse_statement,
OptimizerContext *optimizer_context,
QueryHandle *query_handle) {
LogicalGenerator logical_generator(optimizer_context);
+ PhysicalGenerator physical_generator(optimizer_context);
ExecutionGenerator execution_generator(catalog_database, query_handle);
execution_generator.generatePlan(
- physical_generator_.generatePlan(
+ physical_generator.generatePlan(
logical_generator.generatePlan(*catalog_database, parse_statement)));
}
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/Optimizer.hpp
----------------------------------------------------------------------
diff --git a/query_optimizer/Optimizer.hpp b/query_optimizer/Optimizer.hpp
index 36f956a..227dd04 100644
--- a/query_optimizer/Optimizer.hpp
+++ b/query_optimizer/Optimizer.hpp
@@ -70,8 +70,6 @@ class Optimizer {
QueryHandle *query_handle);
private:
- PhysicalGenerator physical_generator_;
-
DISALLOW_COPY_AND_ASSIGN(Optimizer);
};
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/PhysicalGenerator.cpp
----------------------------------------------------------------------
diff --git a/query_optimizer/PhysicalGenerator.cpp b/query_optimizer/PhysicalGenerator.cpp
index 7cb97dc..b2094e2 100644
--- a/query_optimizer/PhysicalGenerator.cpp
+++ b/query_optimizer/PhysicalGenerator.cpp
@@ -28,6 +28,7 @@
#include "query_optimizer/physical/Physical.hpp"
#include "query_optimizer/rules/AttachLIPFilters.hpp"
#include "query_optimizer/rules/PruneColumns.hpp"
+#include "query_optimizer/rules/ReduceGroupByAttributes.hpp"
#include "query_optimizer/rules/StarSchemaHashJoinOrderOptimization.hpp"
#include "query_optimizer/rules/SwapProbeBuild.hpp"
#include "query_optimizer/strategy/Aggregate.hpp"
@@ -103,6 +104,7 @@ P::PhysicalPtr PhysicalGenerator::generateInitialPlan(
P::PhysicalPtr PhysicalGenerator::optimizePlan() {
std::vector<std::unique_ptr<Rule<P::Physical>>> rules;
rules.emplace_back(new PruneColumns());
+ rules.emplace_back(new ReduceGroupByAttributes(optimizer_context_));
if (FLAGS_reorder_hash_joins) {
rules.emplace_back(new StarSchemaHashJoinOrderOptimization());
rules.emplace_back(new PruneColumns());
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/PhysicalGenerator.hpp
----------------------------------------------------------------------
diff --git a/query_optimizer/PhysicalGenerator.hpp b/query_optimizer/PhysicalGenerator.hpp
index 886a173..42fea86 100644
--- a/query_optimizer/PhysicalGenerator.hpp
+++ b/query_optimizer/PhysicalGenerator.hpp
@@ -33,6 +33,8 @@
namespace quickstep {
namespace optimizer {
+class OptimizerContext;
+
/** \addtogroup QueryOptimizer
* @{
*/
@@ -43,9 +45,12 @@ namespace optimizer {
class PhysicalGenerator : public LogicalToPhysicalMapper {
public:
/**
- * @brief Constructor
+ * @brief Constructor.
+ *
+ * @param optimizer_context The optimizer context.
*/
- PhysicalGenerator() {
+ explicit PhysicalGenerator(OptimizerContext *optimizer_context)
+ : optimizer_context_(optimizer_context) {
createStrategies();
}
@@ -125,6 +130,8 @@ class PhysicalGenerator : public LogicalToPhysicalMapper {
*/
std::unordered_map<logical::LogicalPtr, physical::PhysicalPtr> logical_to_physical_map_;
+ OptimizerContext *optimizer_context_;
+
/**
* @brief The complete physical plan.
*/
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/cost_model/CMakeLists.txt
----------------------------------------------------------------------
diff --git a/query_optimizer/cost_model/CMakeLists.txt b/query_optimizer/cost_model/CMakeLists.txt
index 90133e7..9463b0a 100644
--- a/query_optimizer/cost_model/CMakeLists.txt
+++ b/query_optimizer/cost_model/CMakeLists.txt
@@ -49,6 +49,7 @@ target_link_libraries(quickstep_queryoptimizer_costmodel_StarSchemaSimpleCostMod
glog
quickstep_catalog_CatalogRelation
quickstep_catalog_CatalogRelationStatistics
+ quickstep_catalog_CatalogTypedefs
quickstep_queryoptimizer_costmodel_CostModel
quickstep_queryoptimizer_expressions_AttributeReference
quickstep_queryoptimizer_expressions_ComparisonExpression
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/cost_model/StarSchemaSimpleCostModel.cpp
----------------------------------------------------------------------
diff --git a/query_optimizer/cost_model/StarSchemaSimpleCostModel.cpp b/query_optimizer/cost_model/StarSchemaSimpleCostModel.cpp
index 75b1b2b..5109cb4 100644
--- a/query_optimizer/cost_model/StarSchemaSimpleCostModel.cpp
+++ b/query_optimizer/cost_model/StarSchemaSimpleCostModel.cpp
@@ -21,11 +21,11 @@
#include <algorithm>
#include <memory>
-#include <unordered_map>
#include <vector>
#include "catalog/CatalogRelation.hpp"
#include "catalog/CatalogRelationStatistics.hpp"
+#include "catalog/CatalogTypedefs.hpp"
#include "query_optimizer/cost_model/CostModel.hpp"
#include "query_optimizer/expressions/AttributeReference.hpp"
#include "query_optimizer/expressions/ComparisonExpression.hpp"
@@ -383,18 +383,79 @@ double StarSchemaSimpleCostModel::estimateSelectivityForPredicate(
std::size_t StarSchemaSimpleCostModel::getNumDistinctValues(
const E::ExprId attribute_id,
const P::TableReferencePtr &table_reference) {
- const CatalogRelation &relation = *table_reference->relation();
- const std::vector<E::AttributeReferencePtr> &attributes = table_reference->attribute_list();
- for (std::size_t i = 0; i < attributes.size(); ++i) {
- if (attributes[i]->id() == attribute_id) {
- const CatalogRelationStatistics &stat = relation.getStatistics();
- if (stat.hasNumDistinctValues(i)) {
- return stat.getNumDistinctValues(i);
+ const auto rel_attr_id =
+ findCatalogRelationAttributeId(table_reference, attribute_id);
+ if (rel_attr_id != kInvalidAttributeID) {
+ const CatalogRelationStatistics &stat =
+ table_reference->relation()->getStatistics();
+ if (stat.hasNumDistinctValues(rel_attr_id)) {
+ return stat.getNumDistinctValues(rel_attr_id);
+ }
+ }
+ return estimateCardinalityForTableReference(table_reference);
+}
+
+bool StarSchemaSimpleCostModel::impliesUniqueAttributes(
+ const P::PhysicalPtr &physical_plan,
+ const std::vector<E::AttributeReferencePtr> &attributes) {
+ switch (physical_plan->getPhysicalType()) {
+ case P::PhysicalType::kAggregate: {
+ const P::AggregatePtr &aggregate =
+ std::static_pointer_cast<const P::Aggregate>(physical_plan);
+ return E::SubsetOfExpressions(aggregate->grouping_expressions(), attributes);
+ }
+ case P::PhysicalType::kHashJoin: {
+ const P::HashJoinPtr &hash_join =
+ std::static_pointer_cast<const P::HashJoin>(physical_plan);
+ bool unique_from_left =
+ impliesUniqueAttributes(hash_join->right(), hash_join->right_join_attributes())
+ && impliesUniqueAttributes(hash_join->left(), attributes);
+ bool unique_from_right =
+ impliesUniqueAttributes(hash_join->left(), hash_join->left_join_attributes())
+ && impliesUniqueAttributes(hash_join->right(), attributes);
+ return unique_from_left || unique_from_right;
+ }
+ case P::PhysicalType::kTableReference: {
+ const P::TableReferencePtr &table_reference =
+ std::static_pointer_cast<const P::TableReference>(physical_plan);
+ const CatalogRelationStatistics &stat =
+ table_reference->relation()->getStatistics();
+ if (stat.hasNumTuples()) {
+ const std::size_t num_tuples = stat.getNumTuples();
+ for (const auto &attr : attributes) {
+ const attribute_id rel_attr_id =
+ findCatalogRelationAttributeId(table_reference, attr->id());
+ if (rel_attr_id != kInvalidAttributeID &&
+ stat.hasNumDistinctValues(rel_attr_id) &&
+ stat.getNumDistinctValues(rel_attr_id) == num_tuples) {
+ return true;
+ }
+ }
}
+ return false;
+ }
+ case P::PhysicalType::kSample: // Fall through
+ case P::PhysicalType::kSelection:
+ case P::PhysicalType::kSort: {
+ DCHECK_EQ(physical_plan->getNumChildren(), 1u);
+ return impliesUniqueAttributes(physical_plan->children()[0], attributes);
+ }
+ default:
break;
+ }
+ return false;
+}
+
+attribute_id StarSchemaSimpleCostModel::findCatalogRelationAttributeId(
+ const physical::TableReferencePtr &table_reference,
+ const expressions::ExprId expr_id) {
+ const auto &attribute_list = table_reference->attribute_list();
+ for (std::size_t i = 0; i < attribute_list.size(); ++i) {
+ if (attribute_list[i]->id() == expr_id) {
+ return i;
}
}
- return estimateCardinalityForTableReference(table_reference);
+ return kInvalidAttributeID;
}
} // namespace cost
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/cost_model/StarSchemaSimpleCostModel.hpp
----------------------------------------------------------------------
diff --git a/query_optimizer/cost_model/StarSchemaSimpleCostModel.hpp b/query_optimizer/cost_model/StarSchemaSimpleCostModel.hpp
index 6f6aa29..d750ca0 100644
--- a/query_optimizer/cost_model/StarSchemaSimpleCostModel.hpp
+++ b/query_optimizer/cost_model/StarSchemaSimpleCostModel.hpp
@@ -23,7 +23,9 @@
#include <cstddef>
#include <vector>
+#include "catalog/CatalogTypedefs.hpp"
#include "query_optimizer/cost_model/CostModel.hpp"
+#include "query_optimizer/expressions/AttributeReference.hpp"
#include "query_optimizer/expressions/ExprId.hpp"
#include "query_optimizer/expressions/Predicate.hpp"
#include "query_optimizer/physical/Aggregate.hpp"
@@ -105,6 +107,21 @@ class StarSchemaSimpleCostModel : public CostModel {
double estimateSelectivityForFilterPredicate(
const physical::PhysicalPtr &physical_plan);
+ /**
+ * @brief Check whether a set of attributes are unique (i.e. have distinct
+ * values) for a relation.
+ *
+ * @param physical_plan The physical plan that corresponds to a relation.
+ * @param attributes The set of attributes to be checked. Note that each
+ * attribute in this set must be an output attribute of the physical
+ * plan.
+ * @return True if it is guaranteed that the attributes are unique; false
+ * otherwise.
+ */
+ bool impliesUniqueAttributes(
+ const physical::PhysicalPtr &physical_plan,
+ const std::vector<expressions::AttributeReferencePtr> &attributes);
+
private:
std::size_t estimateCardinalityForAggregate(
const physical::AggregatePtr &physical_plan);
@@ -144,6 +161,10 @@ class StarSchemaSimpleCostModel : public CostModel {
std::size_t getNumDistinctValues(const expressions::ExprId attribute_id,
const physical::TableReferencePtr &table_reference);
+ // For a table reference attribute, find its correponding catalog attribute.
+ attribute_id findCatalogRelationAttributeId(
+ const physical::TableReferencePtr &table_reference,
+ const expressions::ExprId expr_id);
DISALLOW_COPY_AND_ASSIGN(StarSchemaSimpleCostModel);
};
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/rules/CMakeLists.txt
----------------------------------------------------------------------
diff --git a/query_optimizer/rules/CMakeLists.txt b/query_optimizer/rules/CMakeLists.txt
index 7fffadc..7176a4a 100644
--- a/query_optimizer/rules/CMakeLists.txt
+++ b/query_optimizer/rules/CMakeLists.txt
@@ -25,6 +25,9 @@ add_library(quickstep_queryoptimizer_rules_GenerateJoins GenerateJoins.cpp Gener
add_library(quickstep_queryoptimizer_rules_PruneColumns PruneColumns.cpp PruneColumns.hpp)
add_library(quickstep_queryoptimizer_rules_PushDownFilter PushDownFilter.cpp PushDownFilter.hpp)
add_library(quickstep_queryoptimizer_rules_PushDownSemiAntiJoin PushDownSemiAntiJoin.cpp PushDownSemiAntiJoin.hpp)
+add_library(quickstep_queryoptimizer_rules_ReduceGroupByAttributes
+ ReduceGroupByAttributes.cpp
+ ReduceGroupByAttributes.hpp)
add_library(quickstep_queryoptimizer_rules_Rule ../../empty_src.cpp Rule.hpp)
add_library(quickstep_queryoptimizer_rules_RuleHelper RuleHelper.cpp RuleHelper.hpp)
add_library(quickstep_queryoptimizer_rules_StarSchemaHashJoinOrderOptimization
@@ -118,6 +121,25 @@ target_link_libraries(quickstep_queryoptimizer_rules_PushDownSemiAntiJoin
quickstep_queryoptimizer_logical_PatternMatcher
quickstep_queryoptimizer_rules_TopDownRule
quickstep_utility_Macros)
+target_link_libraries(quickstep_queryoptimizer_rules_ReduceGroupByAttributes
+ quickstep_catalog_CatalogRelation
+ quickstep_queryoptimizer_OptimizerContext
+ quickstep_queryoptimizer_costmodel_StarSchemaSimpleCostModel
+ quickstep_queryoptimizer_expressions_AttributeReference
+ quickstep_queryoptimizer_expressions_ExprId
+ quickstep_queryoptimizer_expressions_ExpressionUtil
+ quickstep_queryoptimizer_expressions_NamedExpression
+ quickstep_queryoptimizer_physical_Aggregate
+ quickstep_queryoptimizer_physical_HashJoin
+ quickstep_queryoptimizer_physical_PatternMatcher
+ quickstep_queryoptimizer_physical_Physical
+ quickstep_queryoptimizer_physical_PhysicalType
+ quickstep_queryoptimizer_physical_TableReference
+ quickstep_queryoptimizer_physical_TopLevelPlan
+ quickstep_queryoptimizer_rules_PruneColumns
+ quickstep_queryoptimizer_rules_Rule
+ quickstep_types_TypeID
+ quickstep_utility_Macros)
target_link_libraries(quickstep_queryoptimizer_rules_Rule
glog
quickstep_utility_Macros)
@@ -213,6 +235,7 @@ target_link_libraries(quickstep_queryoptimizer_rules
quickstep_queryoptimizer_rules_PruneColumns
quickstep_queryoptimizer_rules_PushDownFilter
quickstep_queryoptimizer_rules_PushDownSemiAntiJoin
+ quickstep_queryoptimizer_rules_ReduceGroupByAttributes
quickstep_queryoptimizer_rules_Rule
quickstep_queryoptimizer_rules_RuleHelper
quickstep_queryoptimizer_rules_StarSchemaHashJoinOrderOptimization
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/rules/ReduceGroupByAttributes.cpp
----------------------------------------------------------------------
diff --git a/query_optimizer/rules/ReduceGroupByAttributes.cpp b/query_optimizer/rules/ReduceGroupByAttributes.cpp
new file mode 100644
index 0000000..99e17b3
--- /dev/null
+++ b/query_optimizer/rules/ReduceGroupByAttributes.cpp
@@ -0,0 +1,211 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ **/
+
+#include "query_optimizer/rules/ReduceGroupByAttributes.hpp"
+
+#include <algorithm>
+#include <map>
+#include <vector>
+#include <unordered_set>
+#include <utility>
+
+#include "catalog/CatalogRelation.hpp"
+#include "query_optimizer/OptimizerContext.hpp"
+#include "query_optimizer/cost_model/StarSchemaSimpleCostModel.hpp"
+#include "query_optimizer/expressions/AttributeReference.hpp"
+#include "query_optimizer/expressions/ExprId.hpp"
+#include "query_optimizer/expressions/ExpressionUtil.hpp"
+#include "query_optimizer/expressions/NamedExpression.hpp"
+#include "query_optimizer/physical/Aggregate.hpp"
+#include "query_optimizer/physical/HashJoin.hpp"
+#include "query_optimizer/physical/PatternMatcher.hpp"
+#include "query_optimizer/physical/Physical.hpp"
+#include "query_optimizer/physical/PhysicalType.hpp"
+#include "query_optimizer/physical/TableReference.hpp"
+#include "query_optimizer/physical/TopLevelPlan.hpp"
+#include "query_optimizer/rules/PruneColumns.hpp"
+#include "types/TypeID.hpp"
+
+#include "glog/logging.h"
+
+namespace quickstep {
+namespace optimizer {
+
+namespace E = ::quickstep::optimizer::expressions;
+namespace P = ::quickstep::optimizer::physical;
+
+P::PhysicalPtr ReduceGroupByAttributes::apply(const P::PhysicalPtr &input) {
+ DCHECK(input->getPhysicalType() == P::PhysicalType::kTopLevelPlan);
+ cost_model_.reset(new cost::StarSchemaSimpleCostModel(
+ std::static_pointer_cast<const P::TopLevelPlan>(input)->shared_subplans()));
+
+ P::PhysicalPtr output = applyInternal(input);
+ if (output != input) {
+ output = PruneColumns().apply(output);
+ }
+ return output;
+}
+
+P::PhysicalPtr ReduceGroupByAttributes::applyInternal(const P::PhysicalPtr &input) {
+ std::vector<P::PhysicalPtr> new_children;
+ for (const P::PhysicalPtr &child : input->children()) {
+ new_children.push_back(applyInternal(child));
+ }
+
+ if (new_children != input->children()) {
+ return applyToNode(input->copyWithNewChildren(new_children));
+ } else {
+ return applyToNode(input);
+ }
+}
+
+P::PhysicalPtr ReduceGroupByAttributes::applyToNode(const P::PhysicalPtr &input) {
+ P::TableReferencePtr table_reference;
+ if (P::SomeTableReference::MatchesWithConditionalCast(input, &table_reference)) {
+ // Collect the attributes-to-TableReference mapping info.
+ for (const auto &attr : table_reference->attribute_list()) {
+ source_.emplace(attr->id(), std::make_pair(table_reference, attr));
+ }
+ return input;
+ }
+
+ P::AggregatePtr aggregate;
+ if (!P::SomeAggregate::MatchesWithConditionalCast(input, &aggregate) ||
+ aggregate->grouping_expressions().size() <= 1u) {
+ return input;
+ }
+
+ // Divide the group-by attributes into groups based on their source table.
+ std::map<P::TableReferencePtr, std::vector<E::AttributeReferencePtr>> table_attributes;
+ for (const auto &expr : aggregate->grouping_expressions()) {
+ const auto source_it = source_.find(expr->id());
+ if (source_it != source_.end()) {
+ table_attributes[source_it->second.first].emplace_back(source_it->second.second);
+ }
+ }
+
+ std::unordered_set<E::ExprId> erased_grouping_attr_ids;
+ std::vector<std::pair<P::TableReferencePtr, E::AttributeReferencePtr>> hoisted_tables;
+
+ // For each group (i.e. each source table), if it is profitable then we pull
+ // the table up the aggregation.
+ for (const auto &pair : table_attributes) {
+ const P::TableReferencePtr table = pair.first;
+ const std::vector<E::AttributeReferencePtr> &attributes = pair.second;
+ // TODO(jianqiao): find a cost-based metic instead of hard-coding the threshold
+ // number of group-by attributes.
+ if (attributes.size() <= 3u) {
+ continue;
+ }
+
+ std::vector<AttributeInfo> attr_infos;
+ for (const auto &attr : attributes) {
+ attr_infos.emplace_back(attr,
+ cost_model_->impliesUniqueAttributes(table, {attr}),
+ !attr->getValueType().isVariableLength(),
+ attr->getValueType().maximumByteLength());
+ }
+
+ std::vector<const AttributeInfo *> attr_info_refs;
+ for (const auto &info : attr_infos) {
+ attr_info_refs.emplace_back(&info);
+ }
+ std::sort(attr_info_refs.begin(),
+ attr_info_refs.end(),
+ AttributeInfo::IsBetterThan);
+
+ const AttributeInfo &best_candidate = *attr_info_refs.front();
+ if (!best_candidate.is_unique) {
+ // Cannot find a key attribute. Give up pulling this table up.
+ continue;
+ }
+
+ const E::AttributeReferencePtr key_attribute = best_candidate.attribute;
+ hoisted_tables.emplace_back(table, key_attribute);
+
+ for (const auto &attr : attributes) {
+ if (attr->id() != key_attribute->id()) {
+ erased_grouping_attr_ids.emplace(attr->id());
+ }
+ }
+ }
+
+ if (erased_grouping_attr_ids.empty()) {
+ return input;
+ }
+
+ // Reconstuct the Aggregate node with reduced group-by attributes and then
+ // construct HashJoin nodes on top of the Aggregate.
+ std::vector<E::NamedExpressionPtr> reduced_grouping_expressions;
+ for (const auto &expr : aggregate->grouping_expressions()) {
+ if (erased_grouping_attr_ids.find(expr->id()) == erased_grouping_attr_ids.end()) {
+ reduced_grouping_expressions.emplace_back(expr);
+ }
+ }
+
+ const P::AggregatePtr new_aggregate =
+ P::Aggregate::Create(aggregate->input(),
+ reduced_grouping_expressions,
+ aggregate->aggregate_expressions(),
+ aggregate->filter_predicate());
+
+ P::PhysicalPtr output = new_aggregate;
+ std::vector<E::NamedExpressionPtr> project_expressions =
+ E::ToNamedExpressions(output->getOutputAttributes());
+ for (const auto &pair : hoisted_tables) {
+ const P::TableReferencePtr &source_table = pair.first;
+ const E::AttributeReferencePtr &probe_attribute = pair.second;
+
+ E::AttributeReferencePtr build_attribute;
+ std::vector<E::AttributeReferencePtr> new_attribute_list;
+ for (const auto &attr : source_table->attribute_list()) {
+ if (attr->id() == probe_attribute->id()) {
+ build_attribute =
+ E::AttributeReference::Create(optimizer_context_->nextExprId(),
+ attr->attribute_name(),
+ attr->attribute_alias(),
+ attr->relation_name(),
+ attr->getValueType(),
+ E::AttributeReferenceScope::kLocal);
+ new_attribute_list.emplace_back(build_attribute);
+ } else {
+ new_attribute_list.emplace_back(attr);
+ project_expressions.emplace_back(attr);
+ }
+ }
+
+ DCHECK(build_attribute != nullptr);
+ const P::TableReferencePtr build_side_table =
+ P::TableReference::Create(source_table->relation(),
+ source_table->relation()->getName(),
+ new_attribute_list);
+ output = P::HashJoin::Create(output,
+ build_side_table,
+ {probe_attribute},
+ {build_attribute},
+ nullptr,
+ project_expressions,
+ P::HashJoin::JoinType::kInnerJoin);
+ }
+
+ return output;
+}
+
+} // namespace optimizer
+} // namespace quickstep
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/rules/ReduceGroupByAttributes.hpp
----------------------------------------------------------------------
diff --git a/query_optimizer/rules/ReduceGroupByAttributes.hpp b/query_optimizer/rules/ReduceGroupByAttributes.hpp
new file mode 100644
index 0000000..5a1f295
--- /dev/null
+++ b/query_optimizer/rules/ReduceGroupByAttributes.hpp
@@ -0,0 +1,143 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ **/
+
+#ifndef QUICKSTEP_QUERY_OPTIMIZER_RULES_REDUCE_GROUP_BY_ATTRIBUTES_HPP_
+#define QUICKSTEP_QUERY_OPTIMIZER_RULES_REDUCE_GROUP_BY_ATTRIBUTES_HPP_
+
+#include <cstddef>
+#include <memory>
+#include <string>
+#include <unordered_map>
+#include <utility>
+
+#include "query_optimizer/cost_model/StarSchemaSimpleCostModel.hpp"
+#include "query_optimizer/expressions/AttributeReference.hpp"
+#include "query_optimizer/expressions/ExprId.hpp"
+#include "query_optimizer/physical/Physical.hpp"
+#include "query_optimizer/physical/TableReference.hpp"
+#include "query_optimizer/rules/Rule.hpp"
+#include "utility/Macros.hpp"
+
+namespace quickstep {
+namespace optimizer {
+
+class OptimizerContext;
+
+/**
+ * @brief Rule that applies to a physical plan to reduce the number of group-by
+ * attributes for Aggregate nodes (to improve performance) by pulling
+ * joins up the aggregations.
+ *
+ * For example, let R be a relation with PRIMARY KEY x and attributes y, z. Let
+ * S be a relation with FOREIGN KEY u refering to R(x) and attribute v. Then the
+ * optimization rule will transform the physical plan:
+ * Aggregate(
+ * [input relation]: HashJoin(
+ * [probe relation]: S
+ * [build relation]: R
+ * [join expression]: S.u = R.x
+ * [project attributes]: v, x, y, z
+ * )
+ * [aggregate expression]: SUM(v) AS sum_v
+ * [group-by attributes]: x, y, z
+ * )
+ *
+ * into:
+ * HashJoin(
+ * [probe relation]: Aggregate(
+ * [input relation]: S
+ * [aggregate expression]: SUM(v) AS sum_v
+ * [group-by attribute]: u
+ * ) AS T
+ * [build relation]: R
+ * [join expression]: T.u = R.x
+ * [project attributes]: sum_v, x, y, z
+ * )
+ */
+class ReduceGroupByAttributes : public Rule<physical::Physical> {
+ public:
+ /**
+ * @brief Constructor.
+ *
+ * @param optimizer_context The optimizer context.
+ */
+ explicit ReduceGroupByAttributes(OptimizerContext *optimizer_context)
+ : optimizer_context_(optimizer_context) {}
+
+ ~ReduceGroupByAttributes() override {}
+
+ std::string getName() const override {
+ return "ReduceGroupByAttributes";
+ }
+
+ physical::PhysicalPtr apply(const physical::PhysicalPtr &input) override;
+
+ private:
+ struct AttributeInfo {
+ AttributeInfo(const expressions::AttributeReferencePtr &attribute_in,
+ const bool is_unique_in,
+ const bool is_fixed_length_in,
+ const std::size_t maximum_size_in)
+ : attribute(attribute_in),
+ is_unique(is_unique_in),
+ is_fixed_length(is_fixed_length_in),
+ maximum_size(maximum_size_in) {}
+
+ // In the situation that there are multiple attributes that can serve as the
+ // group-by key, we define an ordering based on aggregation performance (e.g.
+ // it is faster to do aggregation with a fix-length attribute as the group-by
+ // key than with a variable-length attribute).
+ inline static bool IsBetterThan(const AttributeInfo *lhs,
+ const AttributeInfo *rhs) {
+ if (lhs->is_unique != rhs->is_unique) {
+ return lhs->is_unique;
+ }
+ if (lhs->is_fixed_length != rhs->is_fixed_length) {
+ return lhs->is_fixed_length;
+ }
+ if (lhs->maximum_size != rhs->maximum_size) {
+ return lhs->maximum_size < rhs->maximum_size;
+ }
+ return lhs->attribute->id() < rhs->attribute->id();
+ }
+
+ const expressions::AttributeReferencePtr attribute;
+ const bool is_unique;
+ const bool is_fixed_length;
+ const std::size_t maximum_size;
+ };
+
+ physical::PhysicalPtr applyInternal(const physical::PhysicalPtr &input);
+ physical::PhysicalPtr applyToNode(const physical::PhysicalPtr &input);
+
+ OptimizerContext *optimizer_context_;
+ std::unique_ptr<cost::StarSchemaSimpleCostModel> cost_model_;
+
+ // Maps an attribute's id to the TableReference that generates the attribute.
+ std::unordered_map<expressions::ExprId,
+ std::pair<physical::TableReferencePtr,
+ expressions::AttributeReferencePtr>> source_;
+
+ DISALLOW_COPY_AND_ASSIGN(ReduceGroupByAttributes);
+};
+
+} // namespace optimizer
+} // namespace quickstep
+
+#endif // QUICKSTEP_QUERY_OPTIMIZER_RULES_REDUCE_GROUP_BY_ATTRIBUTES_HPP_
http://git-wip-us.apache.org/repos/asf/incubator-quickstep/blob/04db5cd7/query_optimizer/tests/OptimizerTest.cpp
----------------------------------------------------------------------
diff --git a/query_optimizer/tests/OptimizerTest.cpp b/query_optimizer/tests/OptimizerTest.cpp
index 3838638..7eb7a11 100644
--- a/query_optimizer/tests/OptimizerTest.cpp
+++ b/query_optimizer/tests/OptimizerTest.cpp
@@ -62,7 +62,7 @@ OptimizerTest::OptimizerTest()
catalog_database_(
new CatalogDatabase(catalog_.get(), "TestDatabase" /* name */, 0)),
optimizer_context_(new OptimizerContext),
- physical_generator_(new PhysicalGenerator()) {}
+ physical_generator_(new PhysicalGenerator(optimizer_context_.get())) {}
E::AliasPtr OptimizerTest::createAlias(const E::ExpressionPtr &expression,
const std::string &attribute_name,