[GitHub] [beam] damccorm opened a new issue, #20312: Add CSVIO for Java SDK

[GitBox <gi...@apache.org>]

damccorm opened a new issue, #20312:
URL: https://github.com/apache/beam/issues/20312

   Apache Beam has TextIO class which can read text based files line by line, delimited by either a carriage return, newline, or a carriage return and a newline. This approach does not support CSV files which have records that span multiple lines. This is because there could be fields where there is a newline inside the double quotes.
   
   This Stackoverflow question is relevant for a feature that should be added to Apache Beam: [https://stackoverflow.com/questions/51439189/how-to-read-large-csv-with-beam](https://stackoverflow.com/questions/51439189/how-to-read-large-csv-with-beam)
   
   I can think of two libraries we could use for handling CSV files. The first one is using Apache Commons CSV library. Here is some example code which can use CSVRecord class for reading and writing CSV records:
   
   `{color:#172b4d}{{PipelineOptions options = PipelineOptionsFactory.create();`
    `Pipeline pipeline = Pipeline.create(options);`
    `PCollection<CSVRecord> records = pipeline.apply("ReadCSV", CSVIO.read().from("input.csv"));`
    records.apply("WriteCSV", CSVIO.write().to("output.csv"));{color}}}
   
   Another library we could use is Jackson CSV, which allows users to specify schemas for the columns: [https://github.com/FasterXML/jackson-dataformats-text/tree/master/csv](https://github.com/FasterXML/jackson-dataformats-text/tree/master/csv)
   
   The crux of the problem is this: can we read and write large CSV files in parallel, by splitting the records and distribute it to many workers? If so, would it be good to have a feature where Apache Beam supports reading/writing CSV files?
   
   Imported from Jira [BEAM-10030](https://issues.apache.org/jira/browse/BEAM-10030). Original Jira may contain additional context.
   Reported by: auroranil.


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