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Posted to dev@arrow.apache.org by Andy Grove <an...@gmail.com> on 2018/03/31 15:40:59 UTC

How nested can List types be?

The layout document gives examples of List<T> and List<List<T>> but it
wasn't clear to me from this document if the intent is to support nesting
at deeper levels such as List<List<List<T>>>.

Could someone clear that up for me?

Thanks,

Andy.

Re: How nested can List types be?

Posted by Wes McKinney <we...@gmail.com>.

hi Andy,

In List<T>, the type T can be any other type, including other lists.
In the C++ library we limit nesting to 64 levels by default, but this
is a failsafe parameter to permit accidental creation of deeply nested
schemas (see arrow/ipc/message.h)

HTH
Wes

On Sat, Mar 31, 2018 at 11:40 AM, Andy Grove <an...@gmail.com> wrote:
> The layout document gives examples of List<T> and List<List<T>> but it
> wasn't clear to me from this document if the intent is to support nesting
> at deeper levels such as List<List<List<T>>>.
>
> Could someone clear that up for me?
>
> Thanks,
>
> Andy.