alamb opened a new issue, #6961:
URL: https://github.com/apache/arrow-datafusion/issues/6961
Basically the `Unest` exec plan could be made faster if we reduced some
copies. Here is the basic idea in case anyone wants to do that
Thanks @vincev -- what I was confused about is that if I look
at this description:
```
// Create an array with the unnested values of the list array, given the
list
// array:
//
// [1], null, [2, 3, 4], null, [5, 6]
//
// the result array is:
//
// 1, null, 2, 3, 4, null, 5, 6
//
let unnested_array = unnest_array(list_array)?;
``
This looks very much the same to me as calling `list_array.vaules()` to get
access to the underlying values:
https://docs.rs/arrow/latest/arrow/array/struct.GenericListArray.html#method.values
In this case the values array would be more like
```
[1, 2, 3, 4, 5, 6]
```
And the offsets of the list array would be would be like (I think):
```
[0, 1, 1, 3, 3, 6]
```
With a null mask showing the second and fourth element are null
So I was thinking you could calculate the take indices directly from the
offsets / nulls without having to copy all the values out of the underlying
array
_Originally posted by @alamb in
https://github.com/apache/arrow-datafusion/pull/6903#discussion_r1262610832_
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