Re: [I] [Go] ValueOffset of array.Binary panics on last index [arrow]

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

zeroshade commented on issue #38458:
URL: https://github.com/apache/arrow/issues/38458#issuecomment-1809129687

   Sorry for the delay here, I've been at a conference all last week, and an off-site for the week before that.
   
   > Just to note here, using `ValueLen` directly on the array.Binary also panics on the last row index, it also checks for >= on data slice.
   
   This doesn't quite make sense to me. `ValueLen` *should* use `>=` just like `Value` does, because the indices are 0-based. `ValueLen` as it currently is implemented will correctly return the length for the last element in a binary column, and this is verified in the unit tests in `binary_test.go` via `TestBinaryValueLen`. You should never be calling `ValueLen(col.Len())` because it's 0-based, you would call `ValueLen(col.Len()-1)` to get the length of the last element, which would pass the check for `>= a.data.length`.
   
   Am I missing something? Can you provide some sample code that calls `ValueLen` and panics on the last row index that I could test?
   
   Otherwise, I'm gonna put together a PR to add `ValueLen` to the interface


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