message: Add some temporary debug messages.
diff: using namespace duckdb;
  using namespace std;
  +#include <iostream>
  +
  void CommonAggregateOptimizer::VisitOperator(LogicalOperator &op) {
  switch (op.type) {
  case LogicalOperatorType::PROJECTION:
  @@ -29,6 +31,10 @@ LogicalAggregate* CommonAggregateOptimizer::find_logical_aggregate(const vector<
  }
  void CommonAggregateOptimizer::ExtractCommonAggregateExpressions(LogicalOperator &projection) {
  + std::cout << "BEFORE OPTIMIZING:" << std::endl;
  + std::cout << projection.ToString() << std::endl;
  +
  +
  auto aggregate = find_logical_aggregate(projection.children);
  // TODO: should I assert that size of projection.expressions and aggregate.groups + aggregate.expressions are equal?
  @@ -90,4 +96,6 @@ void CommonAggregateOptimizer::ExtractCommonAggregateExpressions(LogicalOperator
  projection.expressions.swap(new_projection_expressions);
  aggregate->expressions.swap(new_aggregate_expressions);
  + std::cout << "AFTER OPTIMIZING:" << std::endl;
  + std::cout << projection.ToString() << std::endl;
  }
  