Chao Sun created HIVE-15055:
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Summary: Column pruning for nested fields in Parquet
Key: HIVE-15055
URL: https://issues.apache.org/jira/browse/HIVE-15055
Project: Hive
Issue Type: Improvement
Components: Logical Optimizer, Physical Optimizer
Reporter: Chao Sun
Assignee: Chao Sun
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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