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From "Raj Bains (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HIVE-11672) Hive Streaming API handles bucketing incorrectly
Date Thu, 27 Aug 2015 23:47:45 GMT
Raj Bains created HIVE-11672:
--------------------------------

             Summary: Hive Streaming API handles bucketing incorrectly
                 Key: HIVE-11672
                 URL: https://issues.apache.org/jira/browse/HIVE-11672
             Project: Hive
          Issue Type: Bug
    Affects Versions: 1.2.1
            Reporter: Raj Bains
            Assignee: Roshan Naik
            Priority: Critical
             Fix For: 1.2.2


Hive Streaming API allows the clients to get a random bucket and then insert data into it.
However, this leads to incorrect bucketing as Hive expects data to be distributed into buckets
based on a hash function applied to bucket key. The data is inserted randomly by the clients
right now. They have no way of
# Knowing what bucket a row (tuple) belongs to
# Asking for a specific bucket

There are optimization such as Sort Merge Join and Bucket Map Join that rely on the data being
correctly distributed across buckets and these will cause incorrect read results if the data
is not distributed correctly.

There are two obvious design choices
# Hive Streaming API should fix this internally by distributing the data correctly
# Hive Streaming API should expose data distribution scheme to the clients and allow them
to distribute the data correctly

The first option will mean every client thread will write to many buckets, causing many small
files in each bucket and too many connections open. this does not seem feasible. The second
option pushes more functionality into the client of the Hive Streaming API, but can maintain
high throughput and write good sized ORC files. This option seems preferable.




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