[jira] [Updated] (SPARK-15654) Reading gzipped files results in duplicate rows

["Cheng Lian (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-15654?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Cheng Lian updated SPARK-15654:
-------------------------------
    Assignee: Takeshi Yamamuro

> Reading gzipped files results in duplicate rows
> -----------------------------------------------
>
>                 Key: SPARK-15654
>                 URL: https://issues.apache.org/jira/browse/SPARK-15654
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.0.0
>            Reporter: Jurriaan Pruis
>            Assignee: Takeshi Yamamuro
>            Priority: Blocker
>
> When gzipped files are larger then {{spark.sql.files.maxPartitionBytes}} reading the file will result in duplicate rows in the dataframe.
> Given an example gzipped wordlist (of 740K bytes):
> {code}
> $ gzcat words.gz |wc -l
> 235886
> {code}
> Reading it using spark results in the following output:
> {code}
> >>> sqlContext.setConf('spark.sql.files.maxPartitionBytes', '1000')
> >>> sqlContext.read.text("/Users/jurriaanpruis/spark/words.gz").count()
> 81244093
> >>> sqlContext.setConf('spark.sql.files.maxPartitionBytes', '10000')
> >>> sqlContext.read.text("/Users/jurriaanpruis/spark/words.gz").count()
> 8348566
> >>> sqlContext.setConf('spark.sql.files.maxPartitionBytes', '100000')
> >>> sqlContext.read.text("/Users/jurriaanpruis/spark/words.gz").count()
> 1051469
> >>> sqlContext.setConf('spark.sql.files.maxPartitionBytes', '1000000')
> >>> sqlContext.read.text("/Users/jurriaanpruis/spark/words.gz").count()
> 235886
> {code}
> You can clearly see how the number of rows scales with the number of partitions.
> Somehow the data is duplicated when the number of partitions exceeds one (which as seen above approximately scales with the partition size). 
> When using distinct you'll get the correct answer:
> {code}
> >>> sqlContext.setConf('spark.sql.files.maxPartitionBytes', '10000')
> >>> sqlContext.read.text("/Users/jurriaanpruis/spark/words.gz").distinct().count()
> 235886
> {code}
> This looks like a pretty serious bug.



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