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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