[
https://issues.apache.org/jira/browse/HIVE-25589?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Krisztian Kasa reassigned HIVE-25589:
-------------------------------------
Assignee: Krisztian Kasa
> SQL: Implement HAVING/QUALIFY predicates for ROW_NUMBER()=1
> -----------------------------------------------------------
>
> Key: HIVE-25589
> URL: https://issues.apache.org/jira/browse/HIVE-25589
> Project: Hive
> Issue Type: Improvement
> Components: CBO, SQL
> Affects Versions: 4.0.0
> Reporter: Gopal Vijayaraghavan
> Assignee: Krisztian Kasa
> Priority: Major
>
> The insert queries which use a row_num()=1 function are inconvenient to write
> or port from an existing workload, because there is no easy way to ignore a
> column in this pattern.
> {code}
> INSERT INTO main_table
> SELECT * from duplicated_table
> QUALIFY ROW_NUMER() OVER (PARTITION BY event_id) = 1;
> {code}
> needs to be rewritten into
> {code}
> INSERT INTO main_table
> select event_id, event_ts, event_attribute, event_metric1, event_metric2,
> event_metric3, event_metric4, .., event_metric43 from
> (select *, ROW_NUMBER() OVER (PARTITION BY event_id) as rnum from
> duplicated_table)
> where rnum=1;
> {code}
> This is a time-consuming and error-prone rewrite (dealing with a messed up
> order of columns between one source and dest table).
> An alternate rewrite would be to do the same or similar syntax using HAVING.
> {code}
> INSERT INTO main_table
> SELECT * from duplicated_table
> HAVING ROW_NUMER() OVER (PARTITION BY event_id) = 1;
> {code}
--
This message was sent by Atlassian Jira
(v8.20.7#820007)
