[GitHub] [beam] chavdaparas commented on issue #18390: Google Cloud Storage TextIO read fails with gz-files having Content-Encoding: gzip header

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

chavdaparas commented on issue #18390:
URL: https://github.com/apache/beam/issues/18390#issuecomment-1422729486

   - you can upload the object to GCS with the `Content-Type` set to indicate compression and NO `Content-Encoding` at all, according to best practices.
   
   `Content-encoding: application/gzip`
   `Content-type:`
   
   in this case the only thing immediately known about the object is that it is gzip-compressed, with no information regarding the underlying object type. Moreover, the object is not eligible for decompressive transcoding.
   reference : https://cloud.google.com/storage/docs/transcoding
   
   beam's `ReadFromText` with `compression_type=CompressionTypes.GZIP` works fine with above option
   
   `p  | "Read GCS File" >> beam.io.ReadFromText(file_pattern=file_path,compression_type=CompressionTypes.GZIP,
                       skip_header_lines=int(skip_header))`
   
   Ways to compress the file 
   1. Implicitly by specifying `gsutil cp -Z <filename> <bucket>`
   2. Explicitly by compressing the file first like `gzip <filename>` and load it to GCS 
   
   For more details around which combination works please see the table below : 
   
   <img width="550" alt="Screenshot 2023-02-08 at 8 26 22 PM" src="https://user-images.githubusercontent.com/27141543/217565746-58d45245-a890-4b43-805a-50a225de77cc.png">
   
   
   
   


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