[jira] [Assigned] (IMPALA-2792) Syntactic sugar for computing aggregates over nested collections.

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

     [ https://issues.apache.org/jira/browse/IMPALA-2792?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gabor Kaszab reassigned IMPALA-2792:
------------------------------------

    Assignee: Tamas Mate

> Syntactic sugar for computing aggregates over nested collections.
> -----------------------------------------------------------------
>
>                 Key: IMPALA-2792
>                 URL: https://issues.apache.org/jira/browse/IMPALA-2792
>             Project: IMPALA
>          Issue Type: New Feature
>          Components: Frontend
>    Affects Versions: Impala 2.3.0
>            Reporter: Alexander Behm
>            Assignee: Tamas Mate
>            Priority: Major
>              Labels: complextype, nested_types, planner, ramp-up, usability
>
> For user convenience and SQL brevity, we should add syntax extensions to concisely express aggregates over nested collections. Internally, we should re-write the concise versions into the more verbose equivalent with a correlated inline view.
> Example A:
> {code}
> New syntax:
> select count(c.orders) from customer c
> Internally rewrite to:
> select cnt from customer c, (select count(*) from c.orders) v
> {code}
> Example B:
> {code}
> New syntax:
> select avg(c.orders.items.price) from customer c
> Internally rewrite to:
> select a from customer c, (select avg(price) from c.orders.items) v
> {code}
> I suggest performing the rewrite inside StmtRewriter.java after rewriting all subqueries from the WHERE clause.
> Similar syntactic improvements should be considered for analytic functions on nested collections.



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