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https://issues.apache.org/jira/browse/SPARK-1849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14000397#comment-14000397
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Mridul Muralidharan commented on SPARK-1849:
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Looks like textFile is probably the wrong api to use.
You cannot recover from badly encoded data ... Better would be to write your
own InputFormat which does what you need.
> Broken UTF-8 encoded data gets character replacements and thus can't be
> "fixed"
> -------------------------------------------------------------------------------
>
> Key: SPARK-1849
> URL: https://issues.apache.org/jira/browse/SPARK-1849
> Project: Spark
> Issue Type: Bug
> Reporter: Harry Brundage
> Fix For: 1.0.0, 0.9.1
>
> Attachments: encoding_test
>
>
> I'm trying to process a file which isn't valid UTF-8 data inside hadoop using
> Spark via {{sc.textFile()}}. Is this possible, and if not, is this a bug that
> we should fix? It looks like {{HadoopRDD}} uses
> {{org.apache.hadoop.io.Text.toString}} on all the data it ever reads, which I
> believe replaces invalid UTF-8 byte sequences with the UTF-8 replacement
> character, \uFFFD. Some example code mimicking what {{sc.textFile}} does
> underneath:
> {code}
> scala> sc.textFile(path).collect()(0)
> res8: String = ?pple
> scala> sc.hadoopFile(path, classOf[TextInputFormat], classOf[LongWritable],
> classOf[Text]).map(pair => pair._2.toString).collect()(0).getBytes()
> res9: Array[Byte] = Array(-17, -65, -67, 112, 112, 108, 101)
> scala> sc.hadoopFile(path, classOf[TextInputFormat], classOf[LongWritable],
> classOf[Text]).map(pair => pair._2.getBytes).collect()(0)
> res10: Array[Byte] = Array(-60, 112, 112, 108, 101)
> {code}
> In the above example, the first two snippets show the string representation
> and byte representation of the example line of text. The third snippet shows
> what happens if you call {{getBytes}} on the {{Text}} object which comes back
> from hadoop land: we get the real bytes in the file out.
> Now, I think this is a bug, though you may disagree. The text inside my file
> is perfectly valid iso-8859-1 encoded bytes, which I would like to be able to
> rescue and re-encode into UTF-8, because I want my application to be smart
> like that. I think Spark should give me the raw broken string so I can
> re-encode, but I can't get at the original bytes in order to guess at what
> the source encoding might be, as they have already been replaced. I'm dealing
> with data from some CDN access logs which are to put it nicely diversely
> encoded, but I think a use case Spark should fully support. So, my suggested
> fix, which I'd like some guidance, is to change {{textFile}} to spit out
> broken strings by not using {{Text}}'s UTF-8 encoding.
> Further compounding this issue is that my application is actually in PySpark,
> but we can talk about how bytes fly through to Scala land after this if we
> agree that this is an issue at all.
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