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https://issues.apache.org/jira/browse/ARROW-7098?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Micah Kornfield resolved ARROW-7098.
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Fix Version/s: 1.0.0
Resolution: Fixed
Issue resolved by pull request 5790
[https://github.com/apache/arrow/pull/5790]
> [Java] Improve the performance of comparing two memory blocks
> -------------------------------------------------------------
>
> Key: ARROW-7098
> URL: https://issues.apache.org/jira/browse/ARROW-7098
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Java
> Reporter: Liya Fan
> Assignee: Liya Fan
> Priority: Minor
> Labels: pull-request-available
> Fix For: 1.0.0
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> We often use the 8-4-1 paradigm to compare two blocks of memory:
> 1. First compare by 8-byte blocks in a loop
> 2. Then compare by 4-byte blocks in a loop
> 3. Last compare by 1-byte blocks in a loop
> It can be proved that the second loop runs at most once. So we can replace
> the loop with a if statement, which will save us a comparison and two jump
> operations.
> According to the discussion in
> https://github.com/apache/arrow/pull/5508#discussion_r343973982, loop can be
> expensive.
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