[jira] [Closed] (CALCITE-4702) Error when executing query with GROUP BY constant via JDBC adapter

["Liya Fan (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-4702?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Liya Fan closed CALCITE-4702.
-----------------------------

Resolved in release 1.30.0 (2022-03-20)

> Error when executing query with GROUP BY constant via JDBC adapter
> ------------------------------------------------------------------
>
>                 Key: CALCITE-4702
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4702
>             Project: Calcite
>          Issue Type: Bug
>          Components: core, jdbc-adapter
>    Affects Versions: 1.27.0
>            Reporter: Stamatis Zampetakis
>            Assignee: Soumyakanti Das
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.30.0
>
>          Time Spent: 1h 40m
>  Remaining Estimate: 0h
>
> The following functionally equivalent SQL queries are accepted by Calcite and produce a valid plan 
> {noformat}
> select avg(salary) from employee group by true
> select avg(salary) from employee group by 'a'
> {noformat}
> but they may fail if they are executed via the JDBC adapter since not all DBMS allow grouping by constants expressions. Moreover, what works for one may not work for the other. 
> +Examples+
> The {{GROUP BY TRUE}} query works in Postgres, and MySQL but fails in Redshift with the following exception:
> {noformat}
> com.amazon.redshift.util.RedshiftException: ERROR: non-integer constant in GROUP BY
> {noformat}
> The {{GROUP BY 'a'}} query works in MySQL but fails in Postgres with the following exception:
> {noformat}
> ERROR:  non-integer constant in GROUP BY
> {noformat}
> +Edit:+
> The {{GROUP BY}} constant is similar to {{GROUP BY ()}} "nothing" but as shown in the discussion below they are not equivalent. There is a nice [blog post|https://blog.jooq.org/2018/05/25/how-to-group-by-nothing-in-sql/] listing some limitations of various DBMS when it comes to {{GROUP BY ()}}. 



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