[jira] [Comment Edited] (SPARK-1849) Broken UTF-8 encoded data gets character replacements and thus can't be "fixed"

["Harry Brundage (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-1849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14000460#comment-14000460 ] 

Harry Brundage edited comment on SPARK-1849 at 5/16/14 11:02 PM:
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I disagree - the data isn't badly encoded, just not UTF-8 encoded, which when we're talking about data from the internet really isn't all that uncommon. You could extend my specific problem of some lines in the source file being a different encoding to a file entirely encoded in iso-8859-1, which is likely something Spark should deal with considering all the effort put into supporting Windows. I don't think asking users to drop down to writing a custom {{InputFormat}} to deal with the realities of large data is a good move if Spark wants to become the fast and general data processing engine for large scale data.

I could certainly use {{sc.hadoopFile}} to load in my data and work with the {{org.apache.hadoop.io.Text}} objects myself, but A) why force everyone dealing with this issue to go through the pain of figuring that out, and B) I'm in PySpark where I can't actually do that without fancy Py4J trickery. I think encoding issues should be in your face.


was (Author: airhorns):
I disagree - the data isn't badly encoded, just not UTF-8 encoded, which when we're talking about data from the internet really isn't all that uncommon. You could extend my specific problem of some lines in the source file being a different encoding to a file entirely encoded in iso-8859-1, which is likely something Spark should deal with considering all the effort put into supporting Windows. I don't think asking users to drop down to writing custom {{InputFormat}}s to deal with the realities of large data is a good move if Spark wants to become the fast and general data processing engine for large scale data.

I could certainly use {{sc.hadoopFile}} to load in my data and work with the {{org.apache.hadoop.io.Text}} objects myself, but A) why force everyone dealing with this issue to go through the pain of figuring that out, and B) I'm in PySpark where I can't actually do that without fancy Py4J trickery. I think encoding issues should be in your face.

> 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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