[GitHub] [arrow] mapleFU commented on issue #35236: [C++] params about FileReaderImpl::ReadRowGroups

["mapleFU (via GitHub)" <gi...@apache.org>]

mapleFU commented on issue #35236:
URL: https://github.com/apache/arrow/issues/35236#issuecomment-1515674378

   You can also tag the issue with "parquet".
   
   1. Yes. It's Leaf's column index. You can get the column from `SchemaManifest`
   2. Not. If there is not nested struct, they should be near. But if we have nested struct, `schema_fields` would be a tree, and column is flatten.
   
   You can talk a look at comment below:
   
   ```
     /// To get the index for a particular leaf field, one can use
     /// manifest().schema_fields to get the top level fields, and then walk the
     /// tree to identify the relevant leaf fields and access its column_index.
     /// To get the total number of leaf fields, use FileMetadata.num_columns().
   ```
   
   


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