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https://issues.apache.org/jira/browse/HIVE-7617?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14366220#comment-14366220
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Sergey Shelukhin commented on HIVE-7617:
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Parts of this patch not related to serialization have been moved to HIVE-9997;
the rest will be re-evaluated after vectorized mapjoin patch is in
> optimize bytes mapjoin hash table read path wrt serialization, at least for
> common cases
> ----------------------------------------------------------------------------------------
>
> Key: HIVE-7617
> URL: https://issues.apache.org/jira/browse/HIVE-7617
> Project: Hive
> Issue Type: Improvement
> Reporter: Sergey Shelukhin
> Assignee: Sergey Shelukhin
> Attachments: HIVE-7617.01.patch, HIVE-7617.02.patch,
> HIVE-7617.03.patch, HIVE-7617.03.patch, HIVE-7617.04.patch, HIVE-7617.patch,
> HIVE-7617.prelim.patch, hashmap-wb-fixes.png
>
>
> BytesBytes has table stores keys in the byte array for compact
> representation, however that means that the straightforward implementation of
> lookups serializes lookup keys to byte arrays, which is relatively expensive.
> We can either shortcut hashcode and compare for common types on read path
> (integral types which would cover most of the real-world keys), or specialize
> hashtable and from BytesBytes... create LongBytes, StringBytes, or whatever.
> First one seems simpler now.
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