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Posted to dev@orc.apache.org by GitBox <gi...@apache.org> on 2021/09/30 02:43:20 UTC

[GitHub] [orc] wgtmac commented on pull request #921: ORC-1012: Support specifying columns in orc-scan

wgtmac commented on pull request #921:
URL: https://github.com/apache/orc/pull/921#issuecomment-930704093


   > It's great. Thank you, @stiga-huang . BTW, do we support only ordinal column numbers?
   > 
   > Could you give explain how to select columns from complex types like nested columns like `struct`? It would be great if we can have a test coverage for complex types, too.
   > 
   > cc @wgtmac
   
   The RowReaderOptions support column pruning by fieldName (include(list<string>)), fieldId (include(list<int>)), and columnId (includeTypes(list<int>)). The last one supports pruning nested column in the struct. I think that is what @dongjoon-hyun has mentioned. Support nested pruning requires user to specify the exact columnId which is not easy if the schema is rather complex.


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