[jira] [Updated] (SPARK-26532) repartitionByRange reads source files twice

["Mike Dias (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-26532?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mike Dias updated SPARK-26532:
------------------------------
    Summary: repartitionByRange reads source files twice  (was: repartitionByRange strategy reads source files twice)

> repartitionByRange reads source files twice
> -------------------------------------------
>
>                 Key: SPARK-26532
>                 URL: https://issues.apache.org/jira/browse/SPARK-26532
>             Project: Spark
>          Issue Type: Bug
>          Components: Structured Streaming
>    Affects Versions: 2.3.2, 2.4.0
>            Reporter: Mike Dias
>            Priority: Minor
>         Attachments: repartition Stages.png, repartitionByRange Stages.png
>
>
> When using repartitionByRange in Structured Stream API for reading then write files, it reads the source files twice. 
> Example:
> {code:java}
> val ds = spark.readStream.
>   format("text").
>   option("path", "data/streaming").
>   load
> val q = ds.
>   repartitionByRange(10, $"value").
>   writeStream.
>   format("parquet").
>   option("path", "/tmp/output").
>   option("checkpointLocation", "/tmp/checkpoint").
>   start()
> {code}
> This execution creates 3 stages: 2 for reading and 1 for writing, reading the source twice. It's easy to see it in a large dataset where the reading process time is doubled.
>  
> {code:java}
> $ curl -s -XGET http://localhost:4040/api/v1/applications/<shell_app_id>/stages
> {code}
>  
>  
> This is very different from the repartition strategy, which creates 2 stages: 1 for reading and 1 for writing.
> {code:java}
> val ds = spark.readStream.
>   format("text").
>   option("path", "data/streaming").
>   load
> val q = ds.
>   repartition(10, $"value").
>   writeStream.
>   format("parquet").
>   option("path", "/tmp/output").
>   option("checkpointLocation", "/tmp/checkpoint").
>   start(){code}
>  



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