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https://issues.apache.org/jira/browse/HIVE-15741?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15844233#comment-15844233
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Prasanth Jayachandran commented on HIVE-15741:
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Any reason to use/include commons-logging? Hive moved away from commons-logging
to slf4j (HIVE-6923). If it is a transitive dependency we should add it to
exclusion.
> 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
> Attachments: HIVE-15741.1.patch, HIVE-15741.2.patch,
> HIVE-15741.3.patch
>
>
> 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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