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https://issues.apache.org/jira/browse/HIVE-704?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12737365#action_12737365
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Zheng Shao commented on HIVE-704:
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I think we can do this in two steps:
1. Allow users to give a hint on which table is the "large" table that needs to
have the largest tag;
2. Let hive automatically figure out the "large" table.
1 will help us solve the following problem:
A usual case for join is like this: "fact_table JOIN dim_table_1 JOIN
dim_table_2 JOIN dim_table_3". Currently the only way to do that in Hive is to
use sub queries for each join (since the "large" table needs to be on the
right).
With 1 users don't need to rewrite the query using sub queries, but just need
to give a hint.
> join order should be based on table sizes
> -----------------------------------------
>
> Key: HIVE-704
> URL: https://issues.apache.org/jira/browse/HIVE-704
> Project: Hadoop Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Namit Jain
>
> Currently, hive uses the same order as specified by the user in the query.
> It would be great if that order can be based on the size of tables - largest
> table should be outermost table.
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