phoenix-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (PHOENIX-1556) Base hash versus sort merge join decision on how much data will be scanned
Date Tue, 16 Jan 2018 17:17:00 GMT

     [ https://issues.apache.org/jira/browse/PHOENIX-1556?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

James Taylor updated PHOENIX-1556:
----------------------------------
    Description: 
At compile time, we know how many guideposts (i.e. how many bytes) will be scanned for the
RHS table. We should, by default, base the decision of using the hash-join verus many-to-many
join on this information.

Another criteria (as we've seen in PHOENIX-4508) is whether or not the tables being joined
are already ordered by the join key. In that case, it's better to always use the sort merge
join.

  was:At compile time, we know how many guideposts (i.e. how many bytes) will be scanned for
the RHS table. We should, by default, base the decision of using the hash-join verus many-to-many
join on this information.


> Base hash versus sort merge join decision on how much data will be scanned
> --------------------------------------------------------------------------
>
>                 Key: PHOENIX-1556
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-1556
>             Project: Phoenix
>          Issue Type: Sub-task
>            Reporter: James Taylor
>            Assignee: Maryann Xue
>            Priority: Major
>              Labels: CostBasedOptimization
>
> At compile time, we know how many guideposts (i.e. how many bytes) will be scanned for
the RHS table. We should, by default, base the decision of using the hash-join verus many-to-many
join on this information.
> Another criteria (as we've seen in PHOENIX-4508) is whether or not the tables being
joined are already ordered by the join key. In that case, it's better to always use the sort
merge join.



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

Mime
View raw message