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Posted to dev@hive.apache.org by "Teddy Choi (JIRA)" <ji...@apache.org> on 2017/01/27 01:15:24 UTC

[jira] [Created] (HIVE-15741) Faster unsafe byte array comparisons

Teddy Choi created HIVE-15741:
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             Summary: Faster unsafe byte array comparisons
                 Key: HIVE-15741
                 URL: https://issues.apache.org/jira/browse/HIVE-15741
             Project: Hive
          Issue Type: Improvement
            Reporter: Teddy Choi
            Assignee: Teddy Choi
            Priority: Minor


Byte array comparison is heavily used in joins and string conditions. Pure Java implementation is simple but not performant. An implementation with Unsafe#getLong is much faster. It's already implemented in org.apache.hadoop.io.WritableComparator#compare. The WritableComparator class handles exceptional cases, including a different endian and no access to Unsafe, and it was used for many years in production.

This patch will replace pure Java byte array comparisons with safe and faster unsafe ones to get more performance.



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