[GitHub] [arrow] maqister commented on a change in pull request #11984: PARQUET-2109: Check if Parquet page has too few values

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

maqister commented on a change in pull request #11984:
URL: https://github.com/apache/arrow/pull/11984#discussion_r775112597



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File path: cpp/src/parquet/column_reader.cc
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@@ -940,7 +940,7 @@ int64_t TypedColumnReaderImpl<DType>::ReadBatchWithDictionary(
     int64_t* indices_read, const T** dict, int32_t* dict_len) {
   bool has_dict_output = dict != nullptr && dict_len != nullptr;
   // Similar logic as ReadValues to get pages.
-  if (!HasNext()) {
+  if (batch_size == 0 || !HasNext()) {

Review comment:
       this change breaks use-case in my company where we use this API with batch_size = 0 explicitly, just to obtain dictionary alone. we use it for our loading .parquet files into properitary in-memory column store flow.
   
   it is ok from our perspective to change it as we can just add dedicated API to obtain dictionary in our fork of the code.
   
   i am just bringing this up in case there are other devs impacted by the public API change.
   
   https://www.hyrumslaw.com/




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