hive-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Vineet Garg (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-17767) Rewrite correlated EXISTS/IN subqueries into LEFT SEMI JOIN
Date Fri, 27 Oct 2017 21:16:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-17767?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Vineet Garg updated HIVE-17767:
-------------------------------
    Attachment: HIVE-17767.1.patch

First patch removes earlier commit (which reverted another commit) and adds a rewrite of correlated
EXISTS/IN into LEFT SEMI JOIN. This patch isn't yet ready to be committed since HIVE-17766
isn't in yet.

> Rewrite correlated EXISTS/IN subqueries into LEFT SEMI JOIN
> -----------------------------------------------------------
>
>                 Key: HIVE-17767
>                 URL: https://issues.apache.org/jira/browse/HIVE-17767
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Planning
>            Reporter: Vineet Garg
>            Assignee: Vineet Garg
>         Attachments: HIVE-17767.1.patch
>
>
> Currently such queries are written into group by + inner join with value generator and
is inefficient. Value generator consists of join with outer query to fetch all correlated
values. This value generator could be completely eliminated if such queries are instead rewritten
into LEFT SEMI JOIN.
> Note that to do this first hive need to support LEFT SEMI JOIN with non-equi condition
(HIVE-17766).



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

Mime
View raw message