[
https://issues.apache.org/jira/browse/HIVE-3652?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Amareshwari Sriramadasu updated HIVE-3652:
------------------------------------------
Description:
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.
was:
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 hit 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.
> Join optimization for star schema
> ---------------------------------
>
> Key: HIVE-3652
> URL: https://issues.apache.org/jira/browse/HIVE-3652
> 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.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
