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Re: Nested List examples?


Le 03/05/2018 à 14:28, Andy Grove a écrit :
> Now I have even more questions.
> 
> List<List<T>> uses one values buffer for the instances of T (according to
> Layout.md).
> 
> List<Struct> couldn't possibly do that. Is that a valid type in Arrow?

I think you misread the layout document: it says a list array has
"""A values array, a child array of type T. T may also be a nested
type""".  Note: child array, not buffer.

So, yes, List<Struct> is a valid type. A List<Struct> array has:
* one null bitmap buffer (optional) to designate null lists
* one offsets buffer for list offsets
* one child struct array (which has an arbitrary number of buffers
depending on the struct type)

Regards

Antoine.