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https://issues.apache.org/jira/browse/PIG-2153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13062666#comment-13062666
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Ken Goodhope commented on PIG-2153:
-----------------------------------
The behavior of POProject is correct. LoadFuncs need make sure the pig schema
they return does not include the implicit wrapping tuple. The schema should
only reflect the contents inside the wrapping tuple.
I am not 100% sure how this relates to the issue with ElephantBird, but I am
reasonably convinced the problem there would lie in either how the schema is
built, or possibly how the logical plan is being executed. Regardless I
believe this jira can be closed, since POProject is no longer suspect.
> POProject throws an error with tuples containing a single non-tuple field
> -------------------------------------------------------------------------
>
> Key: PIG-2153
> URL: https://issues.apache.org/jira/browse/PIG-2153
> Project: Pig
> Issue Type: Bug
> Affects Versions: 0.8.1
> Reporter: Ken Goodhope
>
> When POProject.getNext(tuple) processes a tuple with one field, the field is
> pulled out. If that field is not a tuple, a cast exception is thrown. This
> is happening in the folliwing block of code at line 401.
> if(columns.size() == 1) {
> try{
> ret = inpValue.get(columns.get(0));
> ...
> res.result = (Tuple)ret;
> I am seeing this error in a unit test that is loading an array of floats.
> The LoadFunc is converting the array to bag, and wrapping the bag in a tuple.
>
> ({(3.3),(1.2),(5.6)})
> This results on POProject attempting to cast the bag to a tuple. Looking at
> the code, it appears that if I wrapped the previous tuple in another tuple,
> then it would work.
> (({(3.3),(1.2),(5.6)}))
> In this case it would work because POProject would extract the first inner
> tuple and return it. But this would require the LoadFunc to check for tuples
> with a single non-tuple field and only wrap those.
> This could be fixed by first checking that the tuple does actually wrap
> another tuple.
> if(columns.size() == 1 && inpValue.getType(0) == DataType.TUPLE)
> {...
> I don't know the original intent of this code well enough to say this is the
> appropriate fix or not. Hoping someone with more Pig experience can help
> here. Right now this is preventing the unit tests in AvroStorage from
> working. I can change the unit test, but I think in this case the unit test
> is catching a real bug.
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