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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2020/10/27 15:05:04 UTC

[GitHub] [arrow] bkietz commented on a change in pull request #8507: ARROW-10131: [C++][Dataset][Python] Lazily parse parquet metadata

bkietz commented on a change in pull request #8507:
URL: https://github.com/apache/arrow/pull/8507#discussion_r512771071



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File path: cpp/src/arrow/dataset/file_parquet.cc
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@@ -162,8 +148,7 @@ static std::shared_ptr<StructScalar> ColumnChunkStatisticsAsStructScalar(
 
   // Optimize for corner case where all values are nulls
   if (statistics->num_values() == statistics->null_count()) {
-    auto null = MakeNullScalar(field->type());
-    return MakeMinMaxScalar(null, null);
+    return equal(std::move(field_expr), scalar(MakeNullScalar(field->type())));

Review comment:
       Yes, I suppose it'd be more correct to produce `not is_valid(field_expr)` here. `filter=ds.field("col") == pa.NULL` won't select nulls, so I'd like to defer the more correct stats expr to a follow up. 




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