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From "Thejas M Nair (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-9500) Support nested structs over 24 levels.
Date Thu, 05 Feb 2015 19:37:35 GMT

    [ https://issues.apache.org/jira/browse/HIVE-9500?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14307843#comment-14307843
] 

Thejas M Nair commented on HIVE-9500:
-------------------------------------

Some initial comments -
 * Are you sure that UTF8 strings won't have negative byte values ? ( I don't know, I haven't
verified yet. String encoding details are something I fail to retain in my head!).
 * SerDeParameters is not applicable to all serdes, but only to specific sperdes that follow
the lazysimpleserde format. Calling it something like LazySerDeParameters would convey the
meaning better.
 * In LazyUtilsEvery.writeEscaped, with this change every char being written will now result
in 2 HashMap lookups (one for contains, and for get). This is very expensive relative to an
array index lookup. Can you use an offset to make it fit into byte array instead ?

Does reviewboard manage to deal with the patch if the q.out changes are excluded from what
is uploaded ?


> Support nested structs over 24 levels.
> --------------------------------------
>
>                 Key: HIVE-9500
>                 URL: https://issues.apache.org/jira/browse/HIVE-9500
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Aihua Xu
>            Assignee: Aihua Xu
>              Labels: SerDe
>             Fix For: 1.2.0
>
>         Attachments: HIVE-9500.1.patch, HIVE-9500.2.patch
>
>
> Customer has deeply nested avro structure and is receiving the following error when performing
queries.
> 15/01/09 20:59:29 ERROR ql.Driver: FAILED: SemanticException org.apache.hadoop.hive.serde2.SerDeException:
Number of levels of nesting supported for LazySimpleSerde is 23 Unable to work with level
24
> Currently we support up to 24 levels of nested structs when hive.serialization.extend.nesting.levels
is set to true, while the customers have the requirement to support more than that. 
> It would be better to make the supported levels configurable or completely removed (i.e.,
we can support any number of levels). 



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