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From "Jacques Nadeau (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DRILL-2723) Inaccurate row count estimate for text files results in BroadcastExchange
Date Mon, 13 Apr 2015 17:05:12 GMT

     [ https://issues.apache.org/jira/browse/DRILL-2723?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jacques Nadeau updated DRILL-2723:
----------------------------------
    Fix Version/s: 0.9.0

> Inaccurate row count estimate for text files results in BroadcastExchange
> -------------------------------------------------------------------------
>
>                 Key: DRILL-2723
>                 URL: https://issues.apache.org/jira/browse/DRILL-2723
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>            Reporter: Steven Phillips
>            Assignee: Jacques Nadeau
>             Fix For: 0.9.0
>
>
> The current method for estimating row count in text files is to divide the size of the
file in bytes by 1024. This row count estimate is used by optimizer to decide if BroadcastExchange
should be used.
> This results in massive memory consumption when using BroadCast exchange on a large table.
> We need a better way of estimating row count, or use a different metric when deciding
to use BroadcastExchange.



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