[jira] [Commented] (IMPALA-10920) UNNEST function for arrays in the select list

["Gabor Kaszab (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IMPALA-10920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17416560#comment-17416560 ] 

Gabor Kaszab commented on IMPALA-10920:
---------------------------------------

Just for the record, there is an ongoing discussion about the final syntax and the code design on the dev@ mail list:
[https://mail-archives.apache.org/mod_mbox/impala-dev/202109.mbox/thread]
Will post the final conclusion here once we get there.

> UNNEST function for arrays in the select list
> ---------------------------------------------
>
>                 Key: IMPALA-10920
>                 URL: https://issues.apache.org/jira/browse/IMPALA-10920
>             Project: IMPALA
>          Issue Type: New Feature
>          Components: Backend, Frontend
>            Reporter: Gabor Kaszab
>            Assignee: Gabor Kaszab
>            Priority: Major
>              Labels: complextype
>
> There is a need for implementing an UNNEST(array) function that could be given in the select list so that we can replicate Postgres functionality that has the very same.
> Considering the following table:
> {code:java}
> CREATE TABLE tbl (
>   id int,
>   arr1 array<int>,
>   arr2 array<int>)
> STORED AS PARQUET;
> {code}
> with this data:
> {code:java}
> 1, {1,2}, {11,22,33}
> {code}
> A sample query would look like this:
> {code:java}
> SELECT id, UNNEST(arr1), UNNEST(arr2) FROM tbl;
> {code}
> ||id||unnest(arr1)||unnest(arr2)||
> |1|1|11|
> |1|2|22|
> |1|null|33|
> Not that the expected is to 'zip' the arrays instead of joining their values to have the same behaviour as Postgres 10+.



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