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From "Sergey Shelukhin (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-7617) optimize bytes mapjoin hash table read path wrt serialization, at least for common cases
Date Fri, 08 Aug 2014 23:44:12 GMT

     [ https://issues.apache.org/jira/browse/HIVE-7617?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sergey Shelukhin updated HIVE-7617:
-----------------------------------

    Attachment: HIVE-7617.prelim.patch

preliminary patch after some experiments. Need to run tests and then perf tests too

> 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.prelim.patch
>
>
> 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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