//===----------------------------------------------------------------------===// // DuckDB // // duckdb/optimizer/cse_optimizer.hpp // // //===----------------------------------------------------------------------===// #pragma once #include "duckdb/optimizer/rule.hpp" #include "duckdb/parser/expression_map.hpp" #include "duckdb/planner/logical_operator_visitor.hpp" namespace duckdb { class Binder; struct CSEReplacementState; //! The CommonSubExpression optimizer traverses the expressions of a LogicalOperator to look for duplicate expressions //! if there are any, it pushes a projection under the operator that resolves these expressions class CommonSubExpressionOptimizer : public LogicalOperatorVisitor { public: explicit CommonSubExpressionOptimizer(Binder &binder) : binder(binder) { } public: void VisitOperator(LogicalOperator &op) override; private: //! First iteration: count how many times each expression occurs void CountExpressions(Expression &expr, CSEReplacementState &state); //! Second iteration: perform the actual replacement of the duplicate expressions with common subexpressions nodes void PerformCSEReplacement(unique_ptr &expr, CSEReplacementState &state); //! Main method to extract common subexpressions void ExtractCommonSubExpresions(LogicalOperator &op); private: Binder &binder; }; } // namespace duckdb