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From "Teddy Choi (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-15741) Faster unsafe byte array comparisons
Date Fri, 27 Jan 2017 01:22:24 GMT

     [ https://issues.apache.org/jira/browse/HIVE-15741?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Teddy Choi updated HIVE-15741:
------------------------------
    Status: Patch Available  (was: Open)

> 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
>
>
> 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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