[GitHub] [arrow] spenczar commented on pull request #35694: GH-35692: [C++][Parquet] Parquet: tiny fixing FixedSizeListReader::AssembleArray

["spenczar (via GitHub)" <gi...@apache.org>]

spenczar commented on PR #35694:
URL: https://github.com/apache/arrow/pull/35694#issuecomment-1555145609

   Reading https://arrow.apache.org/docs/format/Columnar.html#fixed-size-list-layout more closely, I'm not so sure that the zero-sized elements are correct:
    
   > A fixed size list type is specified like FixedSizeList<T>[N], where T is any type (primitive or nested) and N is a 32-bit signed integer representing the length of the lists.
   >
   > A fixed size list array is represented by a values array, which is a child array of type T. T may also be a nested type. The value in slot j of a fixed size list array is stored in an N-long slice of the values array, starting at an offset of j * N.
   
   `j * N` makes it sound like offsets are always fixed size for fixed size lists. In fact, that document makes it sound like there shouldn't be an offsets buffer at all, since fixed-size lists use "slots". 
   
   Could this actually be a writer bug?
   


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