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https://issues.apache.org/jira/browse/HIVE-12049?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15104177#comment-15104177
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Vaibhav Gumashta commented on HIVE-12049:
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Patch v2 has changes for FileSinkOp.
> Provide an option to write serialized thrift objects in final tasks
> -------------------------------------------------------------------
>
> Key: HIVE-12049
> URL: https://issues.apache.org/jira/browse/HIVE-12049
> Project: Hive
> Issue Type: Sub-task
> Components: HiveServer2
> Reporter: Rohit Dholakia
> Assignee: Rohit Dholakia
> Attachments: HIVE-12049.1.patch, HIVE-12049.2.patch
>
>
> For each fetch request to HiveServer2, we pay the penalty of deserializing
> the row objects and translating them into a different representation suitable
> for the RPC transfer. In a moderate to high concurrency scenarios, this can
> result in significant CPU and memory wastage. By having each task write the
> appropriate thrift objects to the output files, HiveServer2 can simply stream
> a batch of rows on the wire without incurring any of the additional cost of
> deserialization and translation.
> This can be implemented by writing a new SerDe, which the FileSinkOperator
> can use to write thrift formatted row batches to the output file. Using the
> pluggable property of the {{hive.query.result.fileformat}}, we can set it to
> use SequenceFile and write a batch of thrift formatted rows as a value blob.
> The FetchTask can now simply read the blob and send it over the wire. On the
> client side, the *DBC driver can read the blob and since it is already
> formatted in the way it expects, it can continue building the ResultSet the
> way it does in the current implementation.
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