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https://issues.apache.org/jira/browse/HIVE-207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12661424#action_12661424
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Zheng Shao commented on HIVE-207:
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@Joydeep - Yes DynamicSerDe is just a parser for thrift DDL. It calls the
respective methods of the protocol for each field. As a result, it's possible
to write a protocol without a modifying the Dynamic SerDe code. I don't get
your idea of the extensibility hook. I guess the hook is just the same as
DynamicSerDe and its Protocols?
> Change SerDe API to allow skipping unused columns
> -------------------------------------------------
>
> Key: HIVE-207
> URL: https://issues.apache.org/jira/browse/HIVE-207
> Project: Hadoop Hive
> Issue Type: Bug
> Components: Query Processor, Serializers/Deserializers
> Reporter: David Phillips
>
> A deserializer shouldn't have to deserialize columns that are never used by
> the query processor. A serializer shouldn't have to examine unused columns
> that are known to always be null.
> As an example, we store data as a Protocol Buffer structure with ~60 fields.
> Running a "select count(1)" currently requires deserializing all fields,
> which includes checking if they exist and formatting the data appropriately.
> This is expensive and unnecessary.
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