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https://issues.apache.org/jira/browse/ORC-625?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17093657#comment-17093657
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Ted Xu commented on ORC-625:
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Hi folks, I've created a PR [https://github.com/apache/orc/pull/504]
Someone please have a review.
In my test case from production environment, it is tested to have a ~10%
improvement e2e.
> Improve dictionary lookup by marking common prefixes
> ----------------------------------------------------
>
> Key: ORC-625
> URL: https://issues.apache.org/jira/browse/ORC-625
> Project: ORC
> Issue Type: Improvement
> Reporter: Ted Xu
> Priority: Major
>
> Dictionary lookup is slow if there are common prefixes, e.g.,
> {code:java}
> http://foo.bar/a1
> http://foo.bar/a2
> http://foo.bar/a3
> {code}
> It is because dictionary lookup will require comparing values from head every
> time the RedBlack tree finds a new node.
> If the RedBlack tree is able to mark common prefix to parent, we can skip
> some redundant compare.
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