#include "duckdb/optimizer/filter_combiner.hpp"

#include "duckdb/execution/expression_executor.hpp"
#include "duckdb/planner/expression.hpp"
#include "duckdb/planner/expression_iterator.hpp"
#include "duckdb/planner/expression/bound_between_expression.hpp"
#include "duckdb/planner/expression/bound_columnref_expression.hpp"
#include "duckdb/planner/expression/bound_comparison_expression.hpp"
#include "duckdb/planner/expression/bound_conjunction_expression.hpp"
#include "duckdb/planner/expression/bound_constant_expression.hpp"
#include "duckdb/planner/expression/bound_function_expression.hpp"
#include "duckdb/planner/operator/logical_empty_result.hpp"
#include "duckdb/planner/operator/logical_filter.hpp"
#include "duckdb/planner/table_filter.hpp"
#include "duckdb/planner/filter/constant_filter.hpp"
#include "duckdb/planner/filter/null_filter.hpp"
#include "duckdb/optimizer/optimizer.hpp"
#include "duckdb/common/operator/cast_operators.hpp"
#include "duckdb/planner/filter/conjunction_filter.hpp"

namespace duckdb {

using ExpressionValueInformation = FilterCombiner::ExpressionValueInformation;

ValueComparisonResult CompareValueInformation(ExpressionValueInformation &left, ExpressionValueInformation &right);

FilterCombiner::FilterCombiner(ClientContext &context) : context(context) {
}

FilterCombiner::FilterCombiner(Optimizer &optimizer) : FilterCombiner(optimizer.context) {
}

Expression *FilterCombiner::GetNode(Expression *expr) {
	auto entry = stored_expressions.find(expr);
	if (entry != stored_expressions.end()) {
		// expression already exists: return a reference to the stored expression
		return entry->second.get();
	}
	// expression does not exist yet: create a copy and store it
	auto copy = expr->Copy();
	auto pointer_copy = copy.get();
	D_ASSERT(stored_expressions.find(pointer_copy) == stored_expressions.end());
	stored_expressions.insert(make_pair(pointer_copy, move(copy)));
	return pointer_copy;
}

idx_t FilterCombiner::GetEquivalenceSet(Expression *expr) {
	D_ASSERT(stored_expressions.find(expr) != stored_expressions.end());
	D_ASSERT(stored_expressions.find(expr)->second.get() == expr);
	auto entry = equivalence_set_map.find(expr);
	if (entry == equivalence_set_map.end()) {
		idx_t index = set_index++;
		equivalence_set_map[expr] = index;
		equivalence_map[index].push_back(expr);
		constant_values.insert(make_pair(index, vector<ExpressionValueInformation>()));
		return index;
	} else {
		return entry->second;
	}
}

FilterResult FilterCombiner::AddConstantComparison(vector<ExpressionValueInformation> &info_list,
                                                   ExpressionValueInformation info) {
	for (idx_t i = 0; i < info_list.size(); i++) {
		auto comparison = CompareValueInformation(info_list[i], info);
		switch (comparison) {
		case ValueComparisonResult::PRUNE_LEFT:
			// prune the entry from the info list
			info_list.erase(info_list.begin() + i);
			i--;
			break;
		case ValueComparisonResult::PRUNE_RIGHT:
			// prune the current info
			return FilterResult::SUCCESS;
		case ValueComparisonResult::UNSATISFIABLE_CONDITION:
			// combination of filters is unsatisfiable: prune the entire branch
			return FilterResult::UNSATISFIABLE;
		default:
			// prune nothing, move to the next condition
			break;
		}
	}
	// finally add the entry to the list
	info_list.push_back(info);
	return FilterResult::SUCCESS;
}

FilterResult FilterCombiner::AddFilter(unique_ptr<Expression> expr) {
	//	LookUpConjunctions(expr.get());
	// try to push the filter into the combiner
	auto result = AddFilter(expr.get());
	if (result == FilterResult::UNSUPPORTED) {
		// unsupported filter, push into remaining filters
		remaining_filters.push_back(move(expr));
		return FilterResult::SUCCESS;
	}
	return result;
}

void FilterCombiner::GenerateFilters(const std::function<void(unique_ptr<Expression> filter)> &callback) {
	// first loop over the remaining filters
	for (auto &filter : remaining_filters) {
		callback(move(filter));
	}
	remaining_filters.clear();
	// now loop over the equivalence sets
	for (auto &entry : equivalence_map) {
		auto equivalence_set = entry.first;
		auto &entries = entry.second;
		auto &constant_list = constant_values.find(equivalence_set)->second;
		// for each entry generate an equality expression comparing to each other
		for (idx_t i = 0; i < entries.size(); i++) {
			for (idx_t k = i + 1; k < entries.size(); k++) {
				auto comparison = make_unique<BoundComparisonExpression>(ExpressionType::COMPARE_EQUAL,
				                                                         entries[i]->Copy(), entries[k]->Copy());
				callback(move(comparison));
			}
			// for each entry also create a comparison with each constant
			int lower_index = -1, upper_index = -1;
			bool lower_inclusive, upper_inclusive;
			for (idx_t k = 0; k < constant_list.size(); k++) {
				auto &info = constant_list[k];
				if (info.comparison_type == ExpressionType::COMPARE_GREATERTHAN ||
				    info.comparison_type == ExpressionType::COMPARE_GREATERTHANOREQUALTO) {
					lower_index = k;
					lower_inclusive = info.comparison_type == ExpressionType::COMPARE_GREATERTHANOREQUALTO;
				} else if (info.comparison_type == ExpressionType::COMPARE_LESSTHAN ||
				           info.comparison_type == ExpressionType::COMPARE_LESSTHANOREQUALTO) {
					upper_index = k;
					upper_inclusive = info.comparison_type == ExpressionType::COMPARE_LESSTHANOREQUALTO;
				} else {
					auto constant = make_unique<BoundConstantExpression>(info.constant);
					auto comparison = make_unique<BoundComparisonExpression>(info.comparison_type, entries[i]->Copy(),
					                                                         move(constant));
					callback(move(comparison));
				}
			}
			if (lower_index >= 0 && upper_index >= 0) {
				// found both lower and upper index, create a BETWEEN expression
				auto lower_constant = make_unique<BoundConstantExpression>(constant_list[lower_index].constant);
				auto upper_constant = make_unique<BoundConstantExpression>(constant_list[upper_index].constant);
				auto between = make_unique<BoundBetweenExpression>(
				    entries[i]->Copy(), move(lower_constant), move(upper_constant), lower_inclusive, upper_inclusive);
				callback(move(between));
			} else if (lower_index >= 0) {
				// only lower index found, create simple comparison expression
				auto constant = make_unique<BoundConstantExpression>(constant_list[lower_index].constant);
				auto comparison = make_unique<BoundComparisonExpression>(constant_list[lower_index].comparison_type,
				                                                         entries[i]->Copy(), move(constant));
				callback(move(comparison));
			} else if (upper_index >= 0) {
				// only upper index found, create simple comparison expression
				auto constant = make_unique<BoundConstantExpression>(constant_list[upper_index].constant);
				auto comparison = make_unique<BoundComparisonExpression>(constant_list[upper_index].comparison_type,
				                                                         entries[i]->Copy(), move(constant));
				callback(move(comparison));
			}
		}
	}
	stored_expressions.clear();
	equivalence_set_map.clear();
	constant_values.clear();
	equivalence_map.clear();
}

bool FilterCombiner::HasFilters() {
	bool has_filters = false;
	GenerateFilters([&](unique_ptr<Expression> child) { has_filters = true; });
	return has_filters;
}

// unordered_map<idx_t, std::pair<Value *, Value *>> MergeAnd(unordered_map<idx_t, std::pair<Value *, Value *>> &f_1,
//                                                            unordered_map<idx_t, std::pair<Value *, Value *>> &f_2) {
// 	unordered_map<idx_t, std::pair<Value *, Value *>> result;
// 	for (auto &f : f_1) {
// 		auto it = f_2.find(f.first);
// 		if (it == f_2.end()) {
// 			result[f.first] = f.second;
// 		} else {
// 			Value *min = nullptr, *max = nullptr;
// 			if (it->second.first && f.second.first) {
// 				if (*f.second.first > *it->second.first) {
// 					min = f.second.first;
// 				} else {
// 					min = it->second.first;
// 				}

// 			} else if (it->second.first) {
// 				min = it->second.first;
// 			} else if (f.second.first) {
// 				min = f.second.first;
// 			} else {
// 				min = nullptr;
// 			}
// 			if (it->second.second && f.second.second) {
// 				if (*f.second.second < *it->second.second) {
// 					max = f.second.second;
// 				} else {
// 					max = it->second.second;
// 				}
// 			} else if (it->second.second) {
// 				max = it->second.second;
// 			} else if (f.second.second) {
// 				max = f.second.second;
// 			} else {
// 				max = nullptr;
// 			}
// 			result[f.first] = {min, max};
// 			f_2.erase(f.first);
// 		}
// 	}
// 	for (auto &f : f_2) {
// 		result[f.first] = f.second;
// 	}
// 	return result;
// }

// unordered_map<idx_t, std::pair<Value *, Value *>> MergeOr(unordered_map<idx_t, std::pair<Value *, Value *>> &f_1,
//                                                           unordered_map<idx_t, std::pair<Value *, Value *>> &f_2) {
// 	unordered_map<idx_t, std::pair<Value *, Value *>> result;
// 	for (auto &f : f_1) {
// 		auto it = f_2.find(f.first);
// 		if (it != f_2.end()) {
// 			Value *min = nullptr, *max = nullptr;
// 			if (it->second.first && f.second.first) {
// 				if (*f.second.first < *it->second.first) {
// 					min = f.second.first;
// 				} else {
// 					min = it->second.first;
// 				}
// 			}
// 			if (it->second.second && f.second.second) {
// 				if (*f.second.second > *it->second.second) {
// 					max = f.second.second;
// 				} else {
// 					max = it->second.second;
// 				}
// 			}
// 			result[f.first] = {min, max};
// 			f_2.erase(f.first);
// 		}
// 	}
// 	return result;
// }

// unordered_map<idx_t, std::pair<Value *, Value *>>
// FilterCombiner::FindZonemapChecks(vector<idx_t> &column_ids, unordered_set<idx_t> &not_constants, Expression *filter)
// { 	unordered_map<idx_t, std::pair<Value *, Value *>> checks; 	switch (filter->type) { 	case
// ExpressionType::CONJUNCTION_OR: {
// 		//! For a filter to
// 		auto &or_exp = (BoundConjunctionExpression &)*filter;
// 		checks = FindZonemapChecks(column_ids, not_constants, or_exp.children[0].get());
// 		for (size_t i = 1; i < or_exp.children.size(); ++i) {
// 			auto child_check = FindZonemapChecks(column_ids, not_constants, or_exp.children[i].get());
// 			checks = MergeOr(checks, child_check);
// 		}
// 		return checks;
// 	}
// 	case ExpressionType::CONJUNCTION_AND: {
// 		auto &and_exp = (BoundConjunctionExpression &)*filter;
// 		checks = FindZonemapChecks(column_ids, not_constants, and_exp.children[0].get());
// 		for (size_t i = 1; i < and_exp.children.size(); ++i) {
// 			auto child_check = FindZonemapChecks(column_ids, not_constants, and_exp.children[i].get());
// 			checks = MergeAnd(checks, child_check);
// 		}
// 		return checks;
// 	}
// 	case ExpressionType::COMPARE_IN: {
// 		auto &comp_in_exp = (BoundOperatorExpression &)*filter;
// 		if (comp_in_exp.children[0]->type == ExpressionType::BOUND_COLUMN_REF) {
// 			Value *min = nullptr, *max = nullptr;
// 			auto &column_ref = (BoundColumnRefExpression &)*comp_in_exp.children[0].get();
// 			for (size_t i {1}; i < comp_in_exp.children.size(); i++) {
// 				if (comp_in_exp.children[i]->type != ExpressionType::VALUE_CONSTANT) {
// 					//! This indicates the column has a comparison that is not with a constant
// 					not_constants.insert(column_ids[column_ref.binding.column_index]);
// 					break;
// 				} else {
// 					auto &const_value_expr = (BoundConstantExpression &)*comp_in_exp.children[i].get();
// 					if (const_value_expr.value.IsNull()) {
// 						return checks;
// 					}
// 					if (!min && !max) {
// 						min = &const_value_expr.value;
// 						max = min;
// 					} else {
// 						if (*min > const_value_expr.value) {
// 							min = &const_value_expr.value;
// 						}
// 						if (*max < const_value_expr.value) {
// 							max = &const_value_expr.value;
// 						}
// 					}
// 				}
// 			}
// 			checks[column_ids[column_ref.binding.column_index]] = {min, max};
// 		}
// 		return checks;
// 	}
// 	case ExpressionType::COMPARE_EQUAL: {
// 		auto &comp_exp = (BoundComparisonExpression &)*filter;
// 		if ((comp_exp.left->expression_class == ExpressionClass::BOUND_COLUMN_REF &&
// 		     comp_exp.right->expression_class == ExpressionClass::BOUND_CONSTANT)) {
// 			auto &column_ref = (BoundColumnRefExpression &)*comp_exp.left;
// 			auto &constant_value_expr = (BoundConstantExpression &)*comp_exp.right;
// 			checks[column_ids[column_ref.binding.column_index]] = {&constant_value_expr.value,
// 			                                                       &constant_value_expr.value};
// 		}
// 		if ((comp_exp.left->expression_class == ExpressionClass::BOUND_CONSTANT &&
// 		     comp_exp.right->expression_class == ExpressionClass::BOUND_COLUMN_REF)) {
// 			auto &column_ref = (BoundColumnRefExpression &)*comp_exp.right;
// 			auto &constant_value_expr = (BoundConstantExpression &)*comp_exp.left;
// 			checks[column_ids[column_ref.binding.column_index]] = {&constant_value_expr.value,
// 			                                                       &constant_value_expr.value};
// 		}
// 		return checks;
// 	}
// 	case ExpressionType::COMPARE_LESSTHAN:
// 	case ExpressionType::COMPARE_LESSTHANOREQUALTO: {
// 		auto &comp_exp = (BoundComparisonExpression &)*filter;
// 		if ((comp_exp.left->expression_class == ExpressionClass::BOUND_COLUMN_REF &&
// 		     comp_exp.right->expression_class == ExpressionClass::BOUND_CONSTANT)) {
// 			auto &column_ref = (BoundColumnRefExpression &)*comp_exp.left;
// 			auto &constant_value_expr = (BoundConstantExpression &)*comp_exp.right;
// 			checks[column_ids[column_ref.binding.column_index]] = {nullptr, &constant_value_expr.value};
// 		}
// 		if ((comp_exp.left->expression_class == ExpressionClass::BOUND_CONSTANT &&
// 		     comp_exp.right->expression_class == ExpressionClass::BOUND_COLUMN_REF)) {
// 			auto &column_ref = (BoundColumnRefExpression &)*comp_exp.right;
// 			auto &constant_value_expr = (BoundConstantExpression &)*comp_exp.left;
// 			checks[column_ids[column_ref.binding.column_index]] = {&constant_value_expr.value, nullptr};
// 		}
// 		return checks;
// 	}
// 	case ExpressionType::COMPARE_GREATERTHANOREQUALTO:
// 	case ExpressionType::COMPARE_GREATERTHAN: {
// 		auto &comp_exp = (BoundComparisonExpression &)*filter;
// 		if ((comp_exp.left->expression_class == ExpressionClass::BOUND_COLUMN_REF &&
// 		     comp_exp.right->expression_class == ExpressionClass::BOUND_CONSTANT)) {
// 			auto &column_ref = (BoundColumnRefExpression &)*comp_exp.left;
// 			auto &constant_value_expr = (BoundConstantExpression &)*comp_exp.right;
// 			checks[column_ids[column_ref.binding.column_index]] = {&constant_value_expr.value, nullptr};
// 		}
// 		if ((comp_exp.left->expression_class == ExpressionClass::BOUND_CONSTANT &&
// 		     comp_exp.right->expression_class == ExpressionClass::BOUND_COLUMN_REF)) {
// 			auto &column_ref = (BoundColumnRefExpression &)*comp_exp.right;
// 			auto &constant_value_expr = (BoundConstantExpression &)*comp_exp.left;
// 			checks[column_ids[column_ref.binding.column_index]] = {nullptr, &constant_value_expr.value};
// 		}
// 		return checks;
// 	}
// 	default:
// 		return checks;
// 	}
// }

// vector<TableFilter> FilterCombiner::GenerateZonemapChecks(vector<idx_t> &column_ids,
//                                                           vector<TableFilter> &pushed_filters) {
// 	vector<TableFilter> zonemap_checks;
// 	unordered_set<idx_t> not_constants;
// 	//! We go through the remaining filters and capture their min max
// 	if (remaining_filters.empty()) {
// 		return zonemap_checks;
// 	}

// 	auto checks = FindZonemapChecks(column_ids, not_constants, remaining_filters[0].get());
// 	for (size_t i = 1; i < remaining_filters.size(); ++i) {
// 		auto child_check = FindZonemapChecks(column_ids, not_constants, remaining_filters[i].get());
// 		checks = MergeAnd(checks, child_check);
// 	}
// 	//! We construct the equivalent filters
// 	for (auto not_constant : not_constants) {
// 		checks.erase(not_constant);
// 	}
// 	for (const auto &pushed_filter : pushed_filters) {
// 		checks.erase(column_ids[pushed_filter.column_index]);
// 	}
// 	for (const auto &check : checks) {
// 		if (check.second.first) {
// 			zonemap_checks.emplace_back(check.second.first->Copy(), ExpressionType::COMPARE_GREATERTHANOREQUALTO,
// 			                            check.first);
// 		}
// 		if (check.second.second) {
// 			zonemap_checks.emplace_back(check.second.second->Copy(), ExpressionType::COMPARE_LESSTHANOREQUALTO,
// 			                            check.first);
// 		}
// 	}
// 	return zonemap_checks;
// }

TableFilterSet FilterCombiner::GenerateTableScanFilters(vector<idx_t> &column_ids) {
	TableFilterSet table_filters;
	//! First, we figure the filters that have constant expressions that we can push down to the table scan
	for (auto &constant_value : constant_values) {
		if (!constant_value.second.empty()) {
			auto filter_exp = equivalence_map.end();
			if ((constant_value.second[0].comparison_type == ExpressionType::COMPARE_EQUAL ||
			     constant_value.second[0].comparison_type == ExpressionType::COMPARE_GREATERTHAN ||
			     constant_value.second[0].comparison_type == ExpressionType::COMPARE_GREATERTHANOREQUALTO ||
			     constant_value.second[0].comparison_type == ExpressionType::COMPARE_LESSTHAN ||
			     constant_value.second[0].comparison_type == ExpressionType::COMPARE_LESSTHANOREQUALTO) &&
			    (TypeIsNumeric(constant_value.second[0].constant.type().InternalType()) ||
			     constant_value.second[0].constant.type().InternalType() == PhysicalType::VARCHAR ||
			     constant_value.second[0].constant.type().InternalType() == PhysicalType::BOOL)) {
				//! Here we check if these filters are column references
				filter_exp = equivalence_map.find(constant_value.first);
				if (filter_exp->second.size() == 1 && filter_exp->second[0]->type == ExpressionType::BOUND_COLUMN_REF) {
					auto filter_col_exp = static_cast<BoundColumnRefExpression *>(filter_exp->second[0]);
					auto column_index = column_ids[filter_col_exp->binding.column_index];
					if (column_index == COLUMN_IDENTIFIER_ROW_ID) {
						break;
					}
					auto equivalence_set = filter_exp->first;
					auto &entries = filter_exp->second;
					auto &constant_list = constant_values.find(equivalence_set)->second;
					// for each entry generate an equality expression comparing to each other
					for (idx_t i = 0; i < entries.size(); i++) {
						// for each entry also create a comparison with each constant
						for (idx_t k = 0; k < constant_list.size(); k++) {
							auto constant_filter = make_unique<ConstantFilter>(constant_value.second[k].comparison_type,
							                                                   constant_value.second[k].constant);
							table_filters.PushFilter(column_index, move(constant_filter));
						}
						table_filters.PushFilter(column_index, make_unique<IsNotNullFilter>());
					}
					equivalence_map.erase(filter_exp);
				}
			}
		}
	}
	//! Here we look for LIKE or IN filters
	for (idx_t rem_fil_idx = 0; rem_fil_idx < remaining_filters.size(); rem_fil_idx++) {
		auto &remaining_filter = remaining_filters[rem_fil_idx];
		if (remaining_filter->expression_class == ExpressionClass::BOUND_FUNCTION) {
			auto &func = (BoundFunctionExpression &)*remaining_filter;
			if (func.function.name == "prefix" &&
			    func.children[0]->expression_class == ExpressionClass::BOUND_COLUMN_REF &&
			    func.children[1]->type == ExpressionType::VALUE_CONSTANT) {
				//! This is a like function.
				auto &column_ref = (BoundColumnRefExpression &)*func.children[0].get();
				auto &constant_value_expr = (BoundConstantExpression &)*func.children[1].get();
				auto like_string = StringValue::Get(constant_value_expr.value);
				if (like_string.empty()) {
					continue;
				}
				auto column_index = column_ids[column_ref.binding.column_index];
				//! Here the like must be transformed to a BOUND COMPARISON geq le
				auto lower_bound =
				    make_unique<ConstantFilter>(ExpressionType::COMPARE_GREATERTHANOREQUALTO, Value(like_string));
				like_string[like_string.size() - 1]++;
				auto upper_bound = make_unique<ConstantFilter>(ExpressionType::COMPARE_LESSTHAN, Value(like_string));
				table_filters.PushFilter(column_index, move(lower_bound));
				table_filters.PushFilter(column_index, move(upper_bound));
				table_filters.PushFilter(column_index, make_unique<IsNotNullFilter>());
			}
			if (func.function.name == "~~" && func.children[0]->expression_class == ExpressionClass::BOUND_COLUMN_REF &&
			    func.children[1]->type == ExpressionType::VALUE_CONSTANT) {
				//! This is a like function.
				auto &column_ref = (BoundColumnRefExpression &)*func.children[0].get();
				auto &constant_value_expr = (BoundConstantExpression &)*func.children[1].get();
				auto &like_string = StringValue::Get(constant_value_expr.value);
				if (like_string[0] == '%' || like_string[0] == '_') {
					//! We have no prefix so nothing to pushdown
					break;
				}
				string prefix;
				bool equality = true;
				for (char const &c : like_string) {
					if (c == '%' || c == '_') {
						equality = false;
						break;
					}
					prefix += c;
				}
				auto column_index = column_ids[column_ref.binding.column_index];
				if (equality) {
					//! Here the like can be transformed to an equality query
					auto equal_filter = make_unique<ConstantFilter>(ExpressionType::COMPARE_EQUAL, Value(prefix));
					table_filters.PushFilter(column_index, move(equal_filter));
					table_filters.PushFilter(column_index, make_unique<IsNotNullFilter>());
				} else {
					//! Here the like must be transformed to a BOUND COMPARISON geq le
					auto lower_bound =
					    make_unique<ConstantFilter>(ExpressionType::COMPARE_GREATERTHANOREQUALTO, Value(prefix));
					prefix[prefix.size() - 1]++;
					auto upper_bound = make_unique<ConstantFilter>(ExpressionType::COMPARE_LESSTHAN, Value(prefix));
					table_filters.PushFilter(column_index, move(lower_bound));
					table_filters.PushFilter(column_index, move(upper_bound));
					table_filters.PushFilter(column_index, make_unique<IsNotNullFilter>());
				}
			}
		} else if (remaining_filter->type == ExpressionType::COMPARE_IN) {
			auto &func = (BoundOperatorExpression &)*remaining_filter;
			vector<hugeint_t> in_values;
			D_ASSERT(func.children.size() > 1);
			if (func.children[0]->expression_class != ExpressionClass::BOUND_COLUMN_REF) {
				continue;
			}
			auto &column_ref = (BoundColumnRefExpression &)*func.children[0].get();
			auto column_index = column_ids[column_ref.binding.column_index];
			if (column_index == COLUMN_IDENTIFIER_ROW_ID) {
				break;
			}
			//! check if all children are const expr
			bool children_constant = true;
			for (size_t i {1}; i < func.children.size(); i++) {
				if (func.children[i]->type != ExpressionType::VALUE_CONSTANT) {
					children_constant = false;
				}
			}
			if (!children_constant) {
				continue;
			}
			auto &fst_const_value_expr = (BoundConstantExpression &)*func.children[1].get();
			auto &type = fst_const_value_expr.value.type();

			//! Check if values are consecutive, if yes transform them to >= <= (only for integers)
			// e.g. if we have x IN (1, 2, 3, 4, 5) we transform this into x >= 1 AND x <= 5
			if (!type.IsIntegral()) {
				continue;
			}

			bool can_simplify_in_clause = true;
			for (idx_t i = 1; i < func.children.size(); i++) {
				auto &const_value_expr = (BoundConstantExpression &)*func.children[i].get();
				if (const_value_expr.value.IsNull()) {
					can_simplify_in_clause = false;
					break;
				}
				in_values.push_back(const_value_expr.value.GetValue<hugeint_t>());
			}
			if (!can_simplify_in_clause || in_values.empty()) {
				continue;
			}

			sort(in_values.begin(), in_values.end());

			for (idx_t in_val_idx = 1; in_val_idx < in_values.size(); in_val_idx++) {
				if (in_values[in_val_idx] - in_values[in_val_idx - 1] > 1) {
					can_simplify_in_clause = false;
					break;
				}
			}
			if (!can_simplify_in_clause) {
				continue;
			}
			auto lower_bound = make_unique<ConstantFilter>(ExpressionType::COMPARE_GREATERTHANOREQUALTO,
			                                               Value::Numeric(type, in_values.front()));
			auto upper_bound = make_unique<ConstantFilter>(ExpressionType::COMPARE_LESSTHANOREQUALTO,
			                                               Value::Numeric(type, in_values.back()));
			table_filters.PushFilter(column_index, move(lower_bound));
			table_filters.PushFilter(column_index, move(upper_bound));
			table_filters.PushFilter(column_index, make_unique<IsNotNullFilter>());

			remaining_filters.erase(remaining_filters.begin() + rem_fil_idx);
		}
	}

	//	GenerateORFilters(table_filters, column_ids);

	return table_filters;
}

static bool IsGreaterThan(ExpressionType type) {
	return type == ExpressionType::COMPARE_GREATERTHAN || type == ExpressionType::COMPARE_GREATERTHANOREQUALTO;
}

static bool IsLessThan(ExpressionType type) {
	return type == ExpressionType::COMPARE_LESSTHAN || type == ExpressionType::COMPARE_LESSTHANOREQUALTO;
}

FilterResult FilterCombiner::AddBoundComparisonFilter(Expression *expr) {
	auto &comparison = (BoundComparisonExpression &)*expr;
	if (comparison.type != ExpressionType::COMPARE_LESSTHAN &&
	    comparison.type != ExpressionType::COMPARE_LESSTHANOREQUALTO &&
	    comparison.type != ExpressionType::COMPARE_GREATERTHAN &&
	    comparison.type != ExpressionType::COMPARE_GREATERTHANOREQUALTO &&
	    comparison.type != ExpressionType::COMPARE_EQUAL && comparison.type != ExpressionType::COMPARE_NOTEQUAL) {
		// only support [>, >=, <, <=, ==] expressions
		return FilterResult::UNSUPPORTED;
	}
	// check if one of the sides is a scalar value
	bool left_is_scalar = comparison.left->IsFoldable();
	bool right_is_scalar = comparison.right->IsFoldable();
	if (left_is_scalar || right_is_scalar) {
		// comparison with scalar
		auto node = GetNode(left_is_scalar ? comparison.right.get() : comparison.left.get());
		idx_t equivalence_set = GetEquivalenceSet(node);
		auto scalar = left_is_scalar ? comparison.left.get() : comparison.right.get();
		Value constant_value;
		if (!ExpressionExecutor::TryEvaluateScalar(context, *scalar, constant_value)) {
			return FilterResult::UNSATISFIABLE;
		}
		if (constant_value.IsNull()) {
			// comparisons with null are always null (i.e. will never result in rows)
			return FilterResult::UNSATISFIABLE;
		}

		// create the ExpressionValueInformation
		ExpressionValueInformation info;
		info.comparison_type = left_is_scalar ? FlipComparisionExpression(comparison.type) : comparison.type;
		info.constant = constant_value;

		// get the current bucket of constant values
		D_ASSERT(constant_values.find(equivalence_set) != constant_values.end());
		auto &info_list = constant_values.find(equivalence_set)->second;
		// check the existing constant comparisons to see if we can do any pruning
		auto ret = AddConstantComparison(info_list, info);

		auto non_scalar = left_is_scalar ? comparison.right.get() : comparison.left.get();
		auto transitive_filter = FindTransitiveFilter(non_scalar);
		if (transitive_filter != nullptr) {
			// try to add transitive filters
			if (AddTransitiveFilters((BoundComparisonExpression &)*transitive_filter) == FilterResult::UNSUPPORTED) {
				// in case of unsuccessful re-add filter into remaining ones
				remaining_filters.push_back(move(transitive_filter));
			}
		}
		return ret;
	} else {
		// comparison between two non-scalars
		// only handle comparisons for now
		if (expr->type != ExpressionType::COMPARE_EQUAL) {
			if (IsGreaterThan(expr->type) || IsLessThan(expr->type)) {
				return AddTransitiveFilters(comparison);
			}
			return FilterResult::UNSUPPORTED;
		}
		// get the LHS and RHS nodes
		auto left_node = GetNode(comparison.left.get());
		auto right_node = GetNode(comparison.right.get());
		if (BaseExpression::Equals(left_node, right_node)) {
			return FilterResult::UNSUPPORTED;
		}
		// get the equivalence sets of the LHS and RHS
		auto left_equivalence_set = GetEquivalenceSet(left_node);
		auto right_equivalence_set = GetEquivalenceSet(right_node);
		if (left_equivalence_set == right_equivalence_set) {
			// this equality filter already exists, prune it
			return FilterResult::SUCCESS;
		}
		// add the right bucket into the left bucket
		D_ASSERT(equivalence_map.find(left_equivalence_set) != equivalence_map.end());
		D_ASSERT(equivalence_map.find(right_equivalence_set) != equivalence_map.end());

		auto &left_bucket = equivalence_map.find(left_equivalence_set)->second;
		auto &right_bucket = equivalence_map.find(right_equivalence_set)->second;
		for (auto &i : right_bucket) {
			// rewrite the equivalence set mapping for this node
			equivalence_set_map[i] = left_equivalence_set;
			// add the node to the left bucket
			left_bucket.push_back(i);
		}
		// now add all constant values from the right bucket to the left bucket
		D_ASSERT(constant_values.find(left_equivalence_set) != constant_values.end());
		D_ASSERT(constant_values.find(right_equivalence_set) != constant_values.end());
		auto &left_constant_bucket = constant_values.find(left_equivalence_set)->second;
		auto &right_constant_bucket = constant_values.find(right_equivalence_set)->second;
		for (auto &i : right_constant_bucket) {
			if (AddConstantComparison(left_constant_bucket, i) == FilterResult::UNSATISFIABLE) {
				return FilterResult::UNSATISFIABLE;
			}
		}
	}
	return FilterResult::SUCCESS;
}

FilterResult FilterCombiner::AddFilter(Expression *expr) {
	if (expr->HasParameter()) {
		return FilterResult::UNSUPPORTED;
	}
	if (expr->IsFoldable()) {
		// scalar condition, evaluate it
		Value result;
		if (!ExpressionExecutor::TryEvaluateScalar(context, *expr, result)) {
			return FilterResult::UNSUPPORTED;
		}
		result = result.DefaultCastAs(LogicalType::BOOLEAN);
		// check if the filter passes
		if (result.IsNull() || !BooleanValue::Get(result)) {
			// the filter does not pass the scalar test, create an empty result
			return FilterResult::UNSATISFIABLE;
		} else {
			// the filter passes the scalar test, just remove the condition
			return FilterResult::SUCCESS;
		}
	}
	D_ASSERT(!expr->IsFoldable());
	if (expr->GetExpressionClass() == ExpressionClass::BOUND_BETWEEN) {
		auto &comparison = (BoundBetweenExpression &)*expr;
		//! check if one of the sides is a scalar value
		bool lower_is_scalar = comparison.lower->IsFoldable();
		bool upper_is_scalar = comparison.upper->IsFoldable();
		if (lower_is_scalar || upper_is_scalar) {
			//! comparison with scalar - break apart
			auto node = GetNode(comparison.input.get());
			idx_t equivalence_set = GetEquivalenceSet(node);
			auto result = FilterResult::UNSATISFIABLE;

			if (lower_is_scalar) {
				auto scalar = comparison.lower.get();
				Value constant_value;
				if (!ExpressionExecutor::TryEvaluateScalar(context, *scalar, constant_value)) {
					return FilterResult::UNSUPPORTED;
				}

				// create the ExpressionValueInformation
				ExpressionValueInformation info;
				if (comparison.lower_inclusive) {
					info.comparison_type = ExpressionType::COMPARE_GREATERTHANOREQUALTO;
				} else {
					info.comparison_type = ExpressionType::COMPARE_GREATERTHAN;
				}
				info.constant = constant_value;

				// get the current bucket of constant values
				D_ASSERT(constant_values.find(equivalence_set) != constant_values.end());
				auto &info_list = constant_values.find(equivalence_set)->second;
				// check the existing constant comparisons to see if we can do any pruning
				result = AddConstantComparison(info_list, info);
			} else {
				D_ASSERT(upper_is_scalar);
				const auto type = comparison.upper_inclusive ? ExpressionType::COMPARE_LESSTHANOREQUALTO
				                                             : ExpressionType::COMPARE_LESSTHAN;
				auto left = comparison.lower->Copy();
				auto right = comparison.input->Copy();
				auto lower_comp = make_unique<BoundComparisonExpression>(type, move(left), move(right));
				result = AddBoundComparisonFilter(lower_comp.get());
			}

			//	 Stop if we failed
			if (result != FilterResult::SUCCESS) {
				return result;
			}

			if (upper_is_scalar) {
				auto scalar = comparison.upper.get();
				Value constant_value;
				if (!ExpressionExecutor::TryEvaluateScalar(context, *scalar, constant_value)) {
					return FilterResult::UNSUPPORTED;
				}

				// create the ExpressionValueInformation
				ExpressionValueInformation info;
				if (comparison.upper_inclusive) {
					info.comparison_type = ExpressionType::COMPARE_LESSTHANOREQUALTO;
				} else {
					info.comparison_type = ExpressionType::COMPARE_LESSTHAN;
				}
				info.constant = constant_value;

				// get the current bucket of constant values
				D_ASSERT(constant_values.find(equivalence_set) != constant_values.end());
				// check the existing constant comparisons to see if we can do any pruning
				result = AddConstantComparison(constant_values.find(equivalence_set)->second, info);
			} else {
				D_ASSERT(lower_is_scalar);
				const auto type = comparison.upper_inclusive ? ExpressionType::COMPARE_LESSTHANOREQUALTO
				                                             : ExpressionType::COMPARE_LESSTHAN;
				auto left = comparison.input->Copy();
				auto right = comparison.upper->Copy();
				auto upper_comp = make_unique<BoundComparisonExpression>(type, move(left), move(right));
				result = AddBoundComparisonFilter(upper_comp.get());
			}

			return result;
		}
	} else if (expr->GetExpressionClass() == ExpressionClass::BOUND_COMPARISON) {
		return AddBoundComparisonFilter(expr);
	}
	// only comparisons supported for now
	return FilterResult::UNSUPPORTED;
}

/*
 * Create and add new transitive filters from a two non-scalar filter such as j > i, j >= i, j < i, and j <= i
 * It's missing to create another method to add transitive filters from scalar filters, e.g, i > 10
 */
FilterResult FilterCombiner::AddTransitiveFilters(BoundComparisonExpression &comparison) {
	D_ASSERT(IsGreaterThan(comparison.type) || IsLessThan(comparison.type));
	// get the LHS and RHS nodes
	Expression *left_node = GetNode(comparison.left.get());
	Expression *right_node = GetNode(comparison.right.get());
	// In case with filters like CAST(i) = j and i = 5 we replace the COLUMN_REF i with the constant 5
	if (right_node->type == ExpressionType::OPERATOR_CAST) {
		auto &bound_cast_expr = (BoundCastExpression &)*right_node;
		if (bound_cast_expr.child->type == ExpressionType::BOUND_COLUMN_REF) {
			auto &col_ref = (BoundColumnRefExpression &)*bound_cast_expr.child;
			for (auto &stored_exp : stored_expressions) {
				if (stored_exp.first->type == ExpressionType::BOUND_COLUMN_REF) {
					auto &st_col_ref = (BoundColumnRefExpression &)*stored_exp.second;
					if (st_col_ref.binding == col_ref.binding) {
						bound_cast_expr.child = stored_exp.second->Copy();
						right_node = GetNode(bound_cast_expr.child.get());
						break;
					}
				}
			}
		}
	}

	if (BaseExpression::Equals(left_node, right_node)) {
		return FilterResult::UNSUPPORTED;
	}
	// get the equivalence sets of the LHS and RHS
	idx_t left_equivalence_set = GetEquivalenceSet(left_node);
	idx_t right_equivalence_set = GetEquivalenceSet(right_node);
	if (left_equivalence_set == right_equivalence_set) {
		// this equality filter already exists, prune it
		return FilterResult::SUCCESS;
	}

	vector<ExpressionValueInformation> &left_constants = constant_values.find(left_equivalence_set)->second;
	vector<ExpressionValueInformation> &right_constants = constant_values.find(right_equivalence_set)->second;
	bool is_successful = false;
	bool is_inserted = false;
	// read every constant filters already inserted for the right scalar variable
	// and see if we can create new transitive filters, e.g., there is already a filter i > 10,
	// suppose that we have now the j >= i, then we can infer a new filter j > 10
	for (const auto &right_constant : right_constants) {
		ExpressionValueInformation info;
		info.constant = right_constant.constant;
		// there is already an equality filter, e.g., i = 10
		if (right_constant.comparison_type == ExpressionType::COMPARE_EQUAL) {
			// create filter j [>, >=, <, <=] 10
			// suppose the new comparison is j >= i and we have already a filter i = 10,
			// then we create a new filter j >= 10
			// and the filter j >= i can be pruned by not adding it into the remaining filters
			info.comparison_type = comparison.type;
		} else if ((comparison.type == ExpressionType::COMPARE_GREATERTHANOREQUALTO &&
		            IsGreaterThan(right_constant.comparison_type)) ||
		           (comparison.type == ExpressionType::COMPARE_LESSTHANOREQUALTO &&
		            IsLessThan(right_constant.comparison_type))) {
			// filters (j >= i AND i [>, >=] 10) OR (j <= i AND i [<, <=] 10)
			// create filter j [>, >=] 10 and add the filter j [>=, <=] i into the remaining filters
			info.comparison_type = right_constant.comparison_type; // create filter j [>, >=, <, <=] 10
			if (!is_inserted) {
				// Add the filter j >= i in the remaing filters
				auto filter = make_unique<BoundComparisonExpression>(comparison.type, comparison.left->Copy(),
				                                                     comparison.right->Copy());
				remaining_filters.push_back(move(filter));
				is_inserted = true;
			}
		} else if ((comparison.type == ExpressionType::COMPARE_GREATERTHAN &&
		            IsGreaterThan(right_constant.comparison_type)) ||
		           (comparison.type == ExpressionType::COMPARE_LESSTHAN &&
		            IsLessThan(right_constant.comparison_type))) {
			// filters (j > i AND i [>, >=] 10) OR j < i AND i [<, <=] 10
			// create filter j [>, <] 10 and add the filter j [>, <] i into the remaining filters
			// the comparisons j > i and j < i are more restrictive
			info.comparison_type = comparison.type;
			if (!is_inserted) {
				// Add the filter j [>, <] i
				auto filter = make_unique<BoundComparisonExpression>(comparison.type, comparison.left->Copy(),
				                                                     comparison.right->Copy());
				remaining_filters.push_back(move(filter));
				is_inserted = true;
			}
		} else {
			// we cannot add a new filter
			continue;
		}
		// Add the new filer into the left set
		if (AddConstantComparison(left_constants, info) == FilterResult::UNSATISFIABLE) {
			return FilterResult::UNSATISFIABLE;
		}
		is_successful = true;
	}
	if (is_successful) {
		// now check for remaining trasitive filters from the left column
		auto transitive_filter = FindTransitiveFilter(comparison.left.get());
		if (transitive_filter != nullptr) {
			// try to add transitive filters
			if (AddTransitiveFilters((BoundComparisonExpression &)*transitive_filter) == FilterResult::UNSUPPORTED) {
				// in case of unsuccessful re-add filter into remaining ones
				remaining_filters.push_back(move(transitive_filter));
			}
		}
		return FilterResult::SUCCESS;
	}

	return FilterResult::UNSUPPORTED;
}

/*
 * Find a transitive filter already inserted into the remaining filters
 * Check for a match between the right column of bound comparisons and the expression,
 * then removes the bound comparison from the remaining filters and returns it
 */
unique_ptr<Expression> FilterCombiner::FindTransitiveFilter(Expression *expr) {
	// We only check for bound column ref
	if (expr->type == ExpressionType::BOUND_COLUMN_REF) {
		for (idx_t i = 0; i < remaining_filters.size(); i++) {
			if (remaining_filters[i]->GetExpressionClass() == ExpressionClass::BOUND_COMPARISON) {
				auto comparison = (BoundComparisonExpression *)remaining_filters[i].get();
				if (expr->Equals(comparison->right.get()) && comparison->type != ExpressionType::COMPARE_NOTEQUAL) {
					auto filter = move(remaining_filters[i]);
					remaining_filters.erase(remaining_filters.begin() + i);
					return filter;
				}
			}
		}
	}
	return nullptr;
}

ValueComparisonResult InvertValueComparisonResult(ValueComparisonResult result) {
	if (result == ValueComparisonResult::PRUNE_RIGHT) {
		return ValueComparisonResult::PRUNE_LEFT;
	}
	if (result == ValueComparisonResult::PRUNE_LEFT) {
		return ValueComparisonResult::PRUNE_RIGHT;
	}
	return result;
}

ValueComparisonResult CompareValueInformation(ExpressionValueInformation &left, ExpressionValueInformation &right) {
	if (left.comparison_type == ExpressionType::COMPARE_EQUAL) {
		// left is COMPARE_EQUAL, we can either
		// (1) prune the right side or
		// (2) return UNSATISFIABLE
		bool prune_right_side = false;
		switch (right.comparison_type) {
		case ExpressionType::COMPARE_LESSTHAN:
			prune_right_side = left.constant < right.constant;
			break;
		case ExpressionType::COMPARE_LESSTHANOREQUALTO:
			prune_right_side = left.constant <= right.constant;
			break;
		case ExpressionType::COMPARE_GREATERTHAN:
			prune_right_side = left.constant > right.constant;
			break;
		case ExpressionType::COMPARE_GREATERTHANOREQUALTO:
			prune_right_side = left.constant >= right.constant;
			break;
		case ExpressionType::COMPARE_NOTEQUAL:
			prune_right_side = left.constant != right.constant;
			break;
		default:
			D_ASSERT(right.comparison_type == ExpressionType::COMPARE_EQUAL);
			prune_right_side = left.constant == right.constant;
			break;
		}
		if (prune_right_side) {
			return ValueComparisonResult::PRUNE_RIGHT;
		} else {
			return ValueComparisonResult::UNSATISFIABLE_CONDITION;
		}
	} else if (right.comparison_type == ExpressionType::COMPARE_EQUAL) {
		// right is COMPARE_EQUAL
		return InvertValueComparisonResult(CompareValueInformation(right, left));
	} else if (left.comparison_type == ExpressionType::COMPARE_NOTEQUAL) {
		// left is COMPARE_NOTEQUAL, we can either
		// (1) prune the left side or
		// (2) not prune anything
		bool prune_left_side = false;
		switch (right.comparison_type) {
		case ExpressionType::COMPARE_LESSTHAN:
			prune_left_side = left.constant >= right.constant;
			break;
		case ExpressionType::COMPARE_LESSTHANOREQUALTO:
			prune_left_side = left.constant > right.constant;
			break;
		case ExpressionType::COMPARE_GREATERTHAN:
			prune_left_side = left.constant <= right.constant;
			break;
		case ExpressionType::COMPARE_GREATERTHANOREQUALTO:
			prune_left_side = left.constant < right.constant;
			break;
		default:
			D_ASSERT(right.comparison_type == ExpressionType::COMPARE_NOTEQUAL);
			prune_left_side = left.constant == right.constant;
			break;
		}
		if (prune_left_side) {
			return ValueComparisonResult::PRUNE_LEFT;
		} else {
			return ValueComparisonResult::PRUNE_NOTHING;
		}
	} else if (right.comparison_type == ExpressionType::COMPARE_NOTEQUAL) {
		return InvertValueComparisonResult(CompareValueInformation(right, left));
	} else if (IsGreaterThan(left.comparison_type) && IsGreaterThan(right.comparison_type)) {
		// both comparisons are [>], we can either
		// (1) prune the left side or
		// (2) prune the right side
		if (left.constant > right.constant) {
			// left constant is more selective, prune right
			return ValueComparisonResult::PRUNE_RIGHT;
		} else if (left.constant < right.constant) {
			// right constant is more selective, prune left
			return ValueComparisonResult::PRUNE_LEFT;
		} else {
			// constants are equivalent
			// however we can still have the scenario where one is [>=] and the other is [>]
			// we want to prune the [>=] because [>] is more selective
			// if left is [>=] we prune the left, else we prune the right
			if (left.comparison_type == ExpressionType::COMPARE_GREATERTHANOREQUALTO) {
				return ValueComparisonResult::PRUNE_LEFT;
			} else {
				return ValueComparisonResult::PRUNE_RIGHT;
			}
		}
	} else if (IsLessThan(left.comparison_type) && IsLessThan(right.comparison_type)) {
		// both comparisons are [<], we can either
		// (1) prune the left side or
		// (2) prune the right side
		if (left.constant < right.constant) {
			// left constant is more selective, prune right
			return ValueComparisonResult::PRUNE_RIGHT;
		} else if (left.constant > right.constant) {
			// right constant is more selective, prune left
			return ValueComparisonResult::PRUNE_LEFT;
		} else {
			// constants are equivalent
			// however we can still have the scenario where one is [<=] and the other is [<]
			// we want to prune the [<=] because [<] is more selective
			// if left is [<=] we prune the left, else we prune the right
			if (left.comparison_type == ExpressionType::COMPARE_LESSTHANOREQUALTO) {
				return ValueComparisonResult::PRUNE_LEFT;
			} else {
				return ValueComparisonResult::PRUNE_RIGHT;
			}
		}
	} else if (IsLessThan(left.comparison_type)) {
		D_ASSERT(IsGreaterThan(right.comparison_type));
		// left is [<] and right is [>], in this case we can either
		// (1) prune nothing or
		// (2) return UNSATISFIABLE
		// the SMALLER THAN constant has to be greater than the BIGGER THAN constant
		if (left.constant >= right.constant) {
			return ValueComparisonResult::PRUNE_NOTHING;
		} else {
			return ValueComparisonResult::UNSATISFIABLE_CONDITION;
		}
	} else {
		// left is [>] and right is [<] or [!=]
		D_ASSERT(IsLessThan(right.comparison_type) && IsGreaterThan(left.comparison_type));
		return InvertValueComparisonResult(CompareValueInformation(right, left));
	}
}
//
// void FilterCombiner::LookUpConjunctions(Expression *expr) {
//	if (expr->GetExpressionType() == ExpressionType::CONJUNCTION_OR) {
//		auto root_or_expr = (BoundConjunctionExpression *)expr;
//		for (const auto &entry : map_col_conjunctions) {
//			for (const auto &conjs_to_push : entry.second) {
//				if (conjs_to_push->root_or->Equals(root_or_expr)) {
//					return;
//				}
//			}
//		}
//
//		cur_root_or = root_or_expr;
//		cur_conjunction = root_or_expr;
//		cur_colref_to_push = nullptr;
//		if (!BFSLookUpConjunctions(cur_root_or)) {
//			if (cur_colref_to_push) {
//				auto entry = map_col_conjunctions.find(cur_colref_to_push);
//				auto &vec_conjs_to_push = entry->second;
//				if (vec_conjs_to_push.size() == 1) {
//					map_col_conjunctions.erase(entry);
//					return;
//				}
//				vec_conjs_to_push.pop_back();
//			}
//		}
//		return;
//	}
//
//	// Verify if the expression has a column already pushed down by other OR expression
//	VerifyOrsToPush(*expr);
//}
//
// bool FilterCombiner::BFSLookUpConjunctions(BoundConjunctionExpression *conjunction) {
//	vector<BoundConjunctionExpression *> conjunctions_to_visit;
//
//	for (auto &child : conjunction->children) {
//		switch (child->GetExpressionClass()) {
//		case ExpressionClass::BOUND_CONJUNCTION: {
//			auto child_conjunction = (BoundConjunctionExpression *)child.get();
//			conjunctions_to_visit.emplace_back(child_conjunction);
//			break;
//		}
//		case ExpressionClass::BOUND_COMPARISON: {
//			if (!UpdateConjunctionFilter((BoundComparisonExpression *)child.get())) {
//				return false;
//			}
//			break;
//		}
//		default: {
//			return false;
//		}
//		}
//	}
//
//	for (auto child_conjunction : conjunctions_to_visit) {
//		cur_conjunction = child_conjunction;
//		// traverse child conjuction
//		if (!BFSLookUpConjunctions(child_conjunction)) {
//			return false;
//		}
//	}
//	return true;
//}
//
// void FilterCombiner::VerifyOrsToPush(Expression &expr) {
//	if (expr.type == ExpressionType::BOUND_COLUMN_REF) {
//		auto colref = (BoundColumnRefExpression *)&expr;
//		auto entry = map_col_conjunctions.find(colref);
//		if (entry == map_col_conjunctions.end()) {
//			return;
//		}
//		map_col_conjunctions.erase(entry);
//	}
//	ExpressionIterator::EnumerateChildren(expr, [&](Expression &child) { VerifyOrsToPush(child); });
//}
//
// bool FilterCombiner::UpdateConjunctionFilter(BoundComparisonExpression *comparison_expr) {
//	bool left_is_scalar = comparison_expr->left->IsFoldable();
//	bool right_is_scalar = comparison_expr->right->IsFoldable();
//
//	Expression *non_scalar_expr;
//	if (left_is_scalar || right_is_scalar) {
//		// only support comparison with scalar
//		non_scalar_expr = left_is_scalar ? comparison_expr->right.get() : comparison_expr->left.get();
//
//		if (non_scalar_expr->GetExpressionType() == ExpressionType::BOUND_COLUMN_REF) {
//			return UpdateFilterByColumn((BoundColumnRefExpression *)non_scalar_expr, comparison_expr);
//		}
//	}
//
//	return false;
//}
//
// bool FilterCombiner::UpdateFilterByColumn(BoundColumnRefExpression *column_ref,
//                                          BoundComparisonExpression *comparison_expr) {
//	if (cur_colref_to_push == nullptr) {
//		cur_colref_to_push = column_ref;
//
//		auto or_conjunction = make_unique<BoundConjunctionExpression>(ExpressionType::CONJUNCTION_OR);
//		or_conjunction->children.emplace_back(comparison_expr->Copy());
//
//		unique_ptr<ConjunctionsToPush> conjs_to_push = make_unique<ConjunctionsToPush>();
//		conjs_to_push->conjunctions.emplace_back(move(or_conjunction));
//		conjs_to_push->root_or = cur_root_or;
//
//		auto &&vec_col_conjs = map_col_conjunctions[column_ref];
//		vec_col_conjs.emplace_back(move(conjs_to_push));
//		vec_colref_insertion_order.emplace_back(column_ref);
//		return true;
//	}
//
//	auto entry = map_col_conjunctions.find(cur_colref_to_push);
//	D_ASSERT(entry != map_col_conjunctions.end());
//	auto &conjunctions_to_push = entry->second.back();
//
//	if (!cur_colref_to_push->Equals(column_ref)) {
//		// check for multiple colunms in the same root OR node
//		if (cur_root_or == cur_conjunction) {
//			return false;
//		}
//		// found an AND using a different column, we should stop the look up
//		if (cur_conjunction->GetExpressionType() == ExpressionType::CONJUNCTION_AND) {
//			return false;
//		}
//
//		// found a different column, AND conditions cannot be preserved anymore
//		conjunctions_to_push->preserve_and = false;
//		return true;
//	}
//
//	auto &last_conjunction = conjunctions_to_push->conjunctions.back();
//	if (cur_conjunction->GetExpressionType() == last_conjunction->GetExpressionType()) {
//		last_conjunction->children.emplace_back(comparison_expr->Copy());
//	} else {
//		auto new_conjunction = make_unique<BoundConjunctionExpression>(cur_conjunction->GetExpressionType());
//		new_conjunction->children.emplace_back(comparison_expr->Copy());
//		conjunctions_to_push->conjunctions.emplace_back(move(new_conjunction));
//	}
//	return true;
//}
//
// void FilterCombiner::GenerateORFilters(TableFilterSet &table_filter, vector<idx_t> &column_ids) {
//	for (const auto colref : vec_colref_insertion_order) {
//		auto column_index = column_ids[colref->binding.column_index];
//		if (column_index == COLUMN_IDENTIFIER_ROW_ID) {
//			break;
//		}
//
//		for (const auto &conjunctions_to_push : map_col_conjunctions[colref]) {
//			// root OR filter to push into the TableFilter
//			auto root_or_filter = make_unique<ConjunctionOrFilter>();
//			// variable to hold the last conjuntion filter pointer
//			// the next filter will be added into it, i.e., we create a chain of conjunction filters
//			ConjunctionFilter *last_conj_filter = root_or_filter.get();
//
//			for (auto &conjunction : conjunctions_to_push->conjunctions) {
//				if (conjunction->GetExpressionType() == ExpressionType::CONJUNCTION_AND &&
//				    conjunctions_to_push->preserve_and) {
//					GenerateConjunctionFilter<ConjunctionAndFilter>(conjunction.get(), last_conj_filter);
//				} else {
//					GenerateConjunctionFilter<ConjunctionOrFilter>(conjunction.get(), last_conj_filter);
//				}
//			}
//			table_filter.PushFilter(column_index, move(root_or_filter));
//		}
//	}
//	map_col_conjunctions.clear();
//	vec_colref_insertion_order.clear();
//}

} // namespace duckdb
