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https://issues.apache.org/jira/browse/ORC-469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16774465#comment-16774465
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Xiening Dai commented on ORC-469:
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I like the direction we are going. There are a few engines out there which
support compute on dictionary directly (Presto being one of them). Adding this
support would be beneficial to them.
> Add EncodedStringVectorBatch to expose string dictionary in VectorBatch
> -----------------------------------------------------------------------
>
> Key: ORC-469
> URL: https://issues.apache.org/jira/browse/ORC-469
> Project: ORC
> Issue Type: Improvement
> Components: Reader
> Affects Versions: 1.5.5, 1.6.0, 2.0.0
> Reporter: Yurui Zhou
> Priority: Major
>
> Propose to add EncodedStringVectorBatch to expose string dictionary in
> VectorBatch. Exposing string dictionary will benefits as bellow:
> * Enable computation over encoded data. By exposing dictionary in vector
> batch we would be able to implement filter operator in a more efficient way.
> In our POC, by enabling encoded data based filter, we achieved 8% E2E perf
> improvement on tpch q1
> * Make data serialization more efficient. Currently when serializing Orc
> Vectorbatch, we have to copy all the strings in a vector even though the
> string data is already dictionary encoded. Exposing String Dictionary will
> enable vector batch serializer to remove unnecessary string memcpy, which
> will greatly improve serialization efficiency.
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