hive-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jesus Camacho Rodriguez (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-20090) Extend creation of semijoin reduction filters to be able to discover new opportunities
Date Wed, 04 Jul 2018 21:06:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-20090?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jesus Camacho Rodriguez updated HIVE-20090:
-------------------------------------------
    Attachment:     (was: HIVE-20090.patch)

> Extend creation of semijoin reduction filters to be able to discover new opportunities
> --------------------------------------------------------------------------------------
>
>                 Key: HIVE-20090
>                 URL: https://issues.apache.org/jira/browse/HIVE-20090
>             Project: Hive
>          Issue Type: Improvement
>          Components: Physical Optimizer
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>            Priority: Major
>         Attachments: HIVE-20090.01.patch
>
>
> Assume the following plan:
> {noformat}
> TS[0] - RS[1] - JOIN[4] - RS[5] - JOIN[8] - FS[9]
> TS[2] - RS[3] - JOIN[4] 
> TS[6] - RS[7] - JOIN[8]
> {noformat}
> Currently, {{TS\[6\]}} may only be reduced with the output of {{RS\[5\]}}, i.e., input
to join between both subplans.
> However, it may be useful to consider other possibilities too, e.g., reduced by the output
of {{RS\[1\]}} or {{RS\[3\]}}. For instance, this is important when, given a large plan, an
edge between {{RS[5]}} and {{TS[0]}} would create a cycle, while an edge between {{RS[1]}}
and {{TS[6]}} would not.
> This patch comprises two parts. First, it creates additional predicates when possible.
Secondly, it removes duplicate semijoin reduction branches/predicates, e.g., if another semijoin
that consumes the output of the same expression already reduces a certain table scan operator
(heuristic, since this may not result in most efficient plan in all cases). Ultimately, the
decision on whether to use one or another should be cost-driven (follow-up).



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)

Mime
View raw message