William Benton created SPARK-4190:
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             Summary: Allow users to provide transformation rules at JSON ingest
                 Key: SPARK-4190
                 URL: https://issues.apache.org/jira/browse/SPARK-4190
             Project: Spark
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 1.1.0, 1.2.0
            Reporter: William Benton


It would be great if it were possible to provide transformation rules (to be 
executed within jsonRDD or jsonFile) so that users could 

   (1) deal with JSON files that confound schema inference or are otherwise 
insufficiently disciplined, or
   (2) simply perform arbitrary object transformations at ingest before a 
schema is inferred.

json4s, which Spark already uses, has nice interfaces for specifying 
transformations as partial functions on objects and accessing nested structures 
via path expressions.  (We might want to introduce an abstraction atop json4s 
for a public API, but the json4s API seems like a good first step.)  There are 
some examples of these transformations at https://github.com/json4s/json4s and 
at http://chapeau.freevariable.com/2014/10/fedmsg-and-spark.html



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