[GitHub] [arrow] bkietz commented on a change in pull request #10397: ARROW-11930: [C++][Dataset][Compute] Use an ExecPlan for dataset scans

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

bkietz commented on a change in pull request #10397:
URL: https://github.com/apache/arrow/pull/10397#discussion_r640897501



##########
File path: cpp/src/arrow/compute/exec/expression.cc
##########
@@ -492,9 +448,18 @@ Result<Expression> Expression::Bind(ValueDescr in,
   if (literal()) return *this;
 
   if (auto ref = field_ref()) {
-    ARROW_ASSIGN_OR_RAISE(auto field, ref->GetOneOrNone(*in.type));
-    auto descr = field ? ValueDescr{field->type(), in.shape} : ValueDescr::Scalar(null());
-    return Expression{Parameter{*ref, std::move(descr)}};
+    if (ref->IsNested()) {
+      return Status::NotImplemented("nested field references");
+    }
+
+    ARROW_ASSIGN_OR_RAISE(auto path, ref->FindOne(*in.type));

Review comment:
       Extracting indices is necessitated by working with ExecBatches, which don't have named fields (so by-name lookup can't work). What quadratic behavior do you see?




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