Re: unnest on multi-dimensional arrays

Zev Benjamin wrote
> It appears that unnest, when called on a multi-dimensional array,
> effectively flattens the array first. For example:
>
> => select * from unnest(array[array[1, 2], array[2, 3]]);
> unnest
> --------
> 1
> 2
> 2
> 3
> (4 rows)
>
> while I would have expect something like the following:
>
> => select * from unnest(array[array[1, 2], array[2, 3]]);
> unnest
> --------
> {1, 2}
> {2, 3}
> (2 rows)
>
> Is there any way to get the latter behavior?

Manually. Cross-Join the array with a generate-series of the same length
and use the series number as an array index. So row 1 gets cell 1 and so
forth.

Multidimensional arrays do have shortcomings in the current implementation
of which this is one. I'm not sure, though, if there is anything
substantial and centralized in the docs so pertaining. I may look later but
the cross-join+sequence idiom is generally useful and especially for
problems like this.

David J.

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