[jira] [Assigned] (FLINK-9419) UNION should not be treated as retraction producing operator

["Hequn Cheng (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-9419?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hequn Cheng reassigned FLINK-9419:
----------------------------------

    Assignee: Hequn Cheng

> UNION should not be treated as retraction producing operator
> ------------------------------------------------------------
>
>                 Key: FLINK-9419
>                 URL: https://issues.apache.org/jira/browse/FLINK-9419
>             Project: Flink
>          Issue Type: Bug
>          Components: Table API & SQL
>            Reporter: Fabian Hueske
>            Assignee: Hequn Cheng
>            Priority: Major
>
> The following query fails 
> {code}
> SELECT
>     user_id,
>     count(msg),
>     HOP_END(rowtime, INTERVAL '1' second, INTERVAL '1' minute)
> FROM (SELECT rowtime, user_id, action_name AS msg FROM
>           event_client_action
>         WHERE /* various clauses */
>         UNION SELECT rowtime, user_id, action_type AS msg FROM
>            event_server_action
>            WHERE /* various clauses */
>       )
> GROUP BY
> HOP(rowtime, INTERVAL '1' second, INTERVAL '1' minute), user_id
> {code}
> with 
> {quote}Retraction on windowed GroupBy aggregation is not supported yet. Note: Windowed GroupBy aggregation should not follow a non-windowed GroupBy aggregation.{quote}
> The problem is that the {{UNION}} operator is translated into a {{UNION ALL}} and a subsequent {{GROUP BY}} on all attributes without an aggregation function. Currently, all {{GROUP BY}} operators are treated as retraction-producing operators. However, this is only true for grouping operators with aggregation functions. If the operator groups on all attributes and has no aggregation functions, it does not produce retractions but only forwards them (similar to a filter operator).



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