[GitHub] [arrow] bkietz commented on a change in pull request #8311: ARROW-10008: [C++][Dataset] Fix filtering/row group statistics of dict columns

[GitBox <gi...@apache.org>]

bkietz commented on a change in pull request #8311:
URL: https://github.com/apache/arrow/pull/8311#discussion_r497752291



##########
File path: cpp/src/arrow/dataset/filter.cc
##########
@@ -1255,14 +1255,42 @@ struct TreeEvaluator::Impl {
   }
 
   Result<Datum> operator()(const ComparisonExpression& expr) const {
-    ARROW_ASSIGN_OR_RAISE(auto lhs, Evaluate(*expr.left_operand()));
-    ARROW_ASSIGN_OR_RAISE(auto rhs, Evaluate(*expr.right_operand()));
+    ARROW_ASSIGN_OR_RAISE(Datum lhs, Evaluate(*expr.left_operand()));
+    ARROW_ASSIGN_OR_RAISE(Datum rhs, Evaluate(*expr.right_operand()));
 
     if (IsNullDatum(lhs) || IsNullDatum(rhs)) {
       return Datum(std::make_shared<BooleanScalar>());
     }
 
-    DCHECK(lhs.is_array());
+    if (lhs.type()->id() == Type::DICTIONARY && rhs.type()->id() == Type::DICTIONARY) {

Review comment:
       @wesm What do you think about adding kernels to scalar_compare.cc which do this inside compute:: ?




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