Ferdinand Xu updated HIVE-13873:
    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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