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From "Sergey Shelukhin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-13345) LLAP: metadata cache takes too much space, esp. with bloom filters, due to Java/protobuf overhead
Date Mon, 28 Mar 2016 20:26:25 GMT

    [ https://issues.apache.org/jira/browse/HIVE-13345?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15214825#comment-15214825
] 

Sergey Shelukhin commented on HIVE-13345:
-----------------------------------------

I think the problem is/was that ORC readers were created with proto objects. Anyway, I'll
take a look at how complex both approaches are at some point (this week?)

> LLAP: metadata cache takes too much space, esp. with bloom filters, due to Java/protobuf
overhead
> -------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-13345
>                 URL: https://issues.apache.org/jira/browse/HIVE-13345
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Sergey Shelukhin
>
> We cache java objects currently; these have high overhead, average stripe metadata takes
200-500Kb on real files, and with bloom filters blowing up more than x5 due to being stored
as list of Long-s, up to 5Mb per stripe. That is undesirable.
> We should either create better objects for ORC (might be good in general) or store serialized
metadata and deserialize when needed.



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