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https://issues.apache.org/jira/browse/HADOOP-4156?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Namit Jain reassigned HADOOP-4156:
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Assignee: Namit Jain
> [hive] duplicate expression elimination for group by stage 1
> ------------------------------------------------------------
>
> Key: HADOOP-4156
> URL: https://issues.apache.org/jira/browse/HADOOP-4156
> Project: Hadoop Core
> Issue Type: Bug
> Reporter: Namit Jain
> Assignee: Namit Jain
>
> In the first job we evaluate all the input columns + all group by clause
> expressions + parameters to all the aggregation functions and do not
> eliminate all the duplicates because we treat expression resolution and
> column resolution differently.
> Consider the following:
> src(key, value)
> select src.key, sum(src.value) from src group by src;
> Both src.key and src.value will be added twice - one from src's row resolver
> and one each from group expression and parameter. It is needed that way
> filter looks at (table, column) in row resolver, whereas group by expression
> looks
> at (", COLREF table column)
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