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From "Prasanth Jayachandran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-17417) Lazy Timestamp and Date serialization is very expensive
Date Thu, 31 Aug 2017 07:11:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-17417?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16148551#comment-16148551
] 

Prasanth Jayachandran commented on HIVE-17417:
----------------------------------------------

Agreed this is not the most efficient schema. Still this is a possible case as output often
gets written out as lazy simple which has to go through this inefficiency.

> 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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