private static boolean outputsSameAsSource(ProjectNode node) {
    return ImmutableSet.copyOf(node.getOutputSymbols())
        .equals(ImmutableSet.copyOf(node.getChild().getOutputSymbols()));
  }
Removes projection nodes that only perform non-renaming identity projections
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/planner/iterative/rule/RemoveRedundantIdentityProjections.java