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From "Maryann Xue (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (PHOENIX-1556) Base hash versus sort merge join decision on cost
Date Mon, 12 Feb 2018 23:07:00 GMT

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

Maryann Xue updated PHOENIX-1556:
---------------------------------
    Attachment: PHOENIX-1556.patch

> Base hash versus sort merge join decision on cost
> -------------------------------------------------
>
>                 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
>         Attachments: PHOENIX-1556.patch
>
>
> 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.



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