lbug 0.21.0

An in-process property graph database management system built for query speed and scalability
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#pragma once

#include <string>
#include <unordered_map>
#include <unordered_set>

#include "logical_operator_visitor.h"
#include "planner/operator/logical_plan.h"

namespace lbug {
namespace optimizer {

// This optimizer analyzes the dependency between group by keys. If key2 depends on key1 (e.g. key1
// is a primary key column) we only hash on key1 and saves key2 as a payload.
class AggKeyDependencyOptimizer : public LogicalOperatorVisitor {
public:
    void rewrite(planner::LogicalPlan* plan);

private:
    void visitOperator(planner::LogicalOperator* op);

    void visitAggregate(planner::LogicalOperator* op) override;
    void visitDistinct(planner::LogicalOperator* op) override;

    std::pair<binder::expression_vector, binder::expression_vector> resolveKeysAndDependentKeys(
        const binder::expression_vector& keys);

    // Maps a COLLECT-built variable's unique name to the unique names of the group keys it
    // was built over. Populated bottom-up as aggregates are visited.
    std::unordered_map<std::string, std::unordered_set<std::string>> collectVarDeps;
};

} // namespace optimizer
} // namespace lbug