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Posted to issues@hive.apache.org by "Sergey Shelukhin (JIRA)" <ji...@apache.org> on 2017/08/31 03:11:00 UTC

[jira] [Commented] (HIVE-17417) Lazy Timestamp and Date serialization is very expensive

    [ https://issues.apache.org/jira/browse/HIVE-17417?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16148384#comment-16148384 ] 

Sergey Shelukhin commented on HIVE-17417:
-----------------------------------------

That seems like a schema problem in addition to potential serialization inefficiencies.

> Lazy Timestamp and Date serialization is very expensive
> -------------------------------------------------------
>
>                 Key: HIVE-17417
>                 URL: https://issues.apache.org/jira/browse/HIVE-17417
>             Project: Hive
>          Issue Type: Bug
>          Components: Serializers/Deserializers
>    Affects Versions: 3.0.0, 2.4.0
>            Reporter: Prasanth Jayachandran
>            Assignee: Prasanth Jayachandran
>            Priority: Critical
>         Attachments: date-serialize.png, timestamp-serialize.png
>
>
> In a specific case where a schema contains array<struct> with timestamp and date fields (array size >10000). Any access to this column very very expensive in terms of CPU as most of the time is serialization of timestamp and date. Refer attached profiles. >70% time spent in serialization + tostring conversions. 



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