Re: Question about UNNEST

[Gabor Kaszab]

Hi,

For that we'd need functions that can return nested types, but currently
there is no support in Impala for that. It was considered at some point,
there is even a Jira for that, but for some reason no one started working
on that item.

Regards,
Gabor

On Wed, Nov 27, 2024 at 5:00 AM Xiufeng Huang  wrote:

> Hi all,
>
> I was wondering if there is any plan to support UNNEST for expressions in
> Impala like what Postgres does?
>
> Sample sql for reference
> select unnest(string_to_array(col_string, ‘,’)) from tbl
>
> Thanks

Re: Question about UNNEST

[Csaba Ringhofer]

Hi Xiufeng!

This would be great to support in the long term, but currently several
parts are missing:
- there is no Impala function/udf interface in the backend to return
collections or get them as argument, so we cannot create a function like
string_to_array() at the moment
- the frontend planner part is also not simple

There was an attempt to implement functions that can return tables, but
sadly it was stuck in design phase:
https://docs.google.com/document/d/1-dVfGeIfXBpVKtoWmPye11BO7Wn-sQTqBMemKf9zJ4k/edit?tab=t.0#heading=h.rxomr7gsib44

regards,
Csaba

On Wed, Nov 27, 2024 at 5:00 AM Xiufeng Huang  wrote:

> Hi all,
>
> I was wondering if there is any plan to support UNNEST for expressions in
> Impala like what Postgres does?
>
> Sample sql for reference
> select unnest(string_to_array(col_string, ‘,’)) from tbl
>
> Thanks

Question about UNNEST

[Xiufeng Huang]

Hi all,

I was wondering if there is any plan to support UNNEST for expressions in 
Impala like what Postgres does?

Sample sql for reference
select unnest(string_to_array(col_string, ‘,’)) from tbl 

Thanks