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https://issues.apache.org/jira/browse/HIVE-13873?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ferdinand Xu updated HIVE-13873:
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Attachment: HIVE-13873.4.patch
> Column pruning for nested fields
> --------------------------------
>
> Key: HIVE-13873
> URL: https://issues.apache.org/jira/browse/HIVE-13873
> Project: Hive
> Issue Type: New Feature
> Components: Logical Optimizer
> Reporter: Xuefu Zhang
> Assignee: Ferdinand Xu
> Attachments: HIVE-13873.1.patch, HIVE-13873.2.patch,
> HIVE-13873.3.patch, HIVE-13873.4.patch, HIVE-13873.patch, HIVE-13873.wip.patch
>
>
> Some columnar file formats such as Parquet store fields in struct type also
> column by column using encoding described in Google Dramel pager. It's very
> common in big data where data are stored in structs while queries only needs
> a subset of the the fields in the structs. However, presently Hive still
> needs to read the whole struct regardless whether all fields are selected.
> Therefore, pruning unwanted sub-fields in struct or nested fields at file
> reading time would be a big performance boost for such scenarios.
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