[jira] [Created] (SPARK-31276) Contrived working example that works with multiple URI file storages for Spark cluster mode

["Jim Huang (Jira)" <ji...@apache.org>]

Jim Huang created SPARK-31276:
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             Summary: Contrived working example that works with multiple URI file storages for Spark cluster mode
                 Key: SPARK-31276
                 URL: https://issues.apache.org/jira/browse/SPARK-31276
             Project: Spark
          Issue Type: Wish
          Components: Examples
    Affects Versions: 2.4.5
            Reporter: Jim Huang


This Spark SQL Guide --> Data sources --> Generic Load/Save Functions

[https://spark.apache.org/docs/latest/sql-data-sources-load-save-functions.html]

described a very simple "local file system load of an example file".  

 

I am looking for an example that demonstrates a workflow that exercises different file systems.  For example, 
 # Driver loads an input file from local file system
 # Add a simple column using lit() and stores that DataFrame in cluster mode to HDFS
 # Write that same final DataFrame back to Driver's local file system

 

The examples I found on the internet only uses simple paths without the explicit URI prefixes.

Without the explicit URI prefixes, the "filepath" inherits how Spark (mode) was called, local stand alone vs cluster mode.   So a "filepath" will be read/write locally (file system) vs cluster mode HDFS, without these explicit URIs.

There are situations were a Spark program needs to deal with both local file system and cluster mode (big data) in the same Spark application, like producing a summary table stored on the local file system of the driver at the end.  

Thanks.



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