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From "Amareshwari Sriramadasu (JIRA)" <>
Subject [jira] [Commented] (HIVE-3652) Join optimization for star schema
Date Thu, 03 Jan 2013 05:26:15 GMT


Amareshwari Sriramadasu commented on HIVE-3652:

[~vikram.dixit]I'm not working on it right now. May not get time in next one month also. Please
feel free work on it, if interested.
> Join optimization for star schema
> ---------------------------------
>                 Key: HIVE-3652
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Amareshwari Sriramadasu
>            Assignee: Amareshwari Sriramadasu
> Currently, if we join one fact table with multiple dimension tables, it results in multiple
mapreduce jobs for each join with dimension table, because join would be on different keys
for each dimension. 
> Usually all the dimension tables will be small and can fit into memory and so map-side
join can used to join with fact table.
> In this issue I want to look at optimizing such query to generate single mapreduce job
sothat mapper loads dimension tables into memory and joins with fact table on different keys
as well.

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