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From "Sushanth Sowmyan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-4329) HCatalog should use getHiveRecordWriter rather than getRecordWriter
Date Mon, 03 Nov 2014 04:05:35 GMT

    [ https://issues.apache.org/jira/browse/HIVE-4329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14194226#comment-14194226
] 

Sushanth Sowmyan commented on HIVE-4329:
----------------------------------------

(FYI, the issue with PassthroughOutputFormat that I mentioned above is addressed by HIVE-8704
. Note that there is still a further issue with PTOF in that it still will not support having
more than one OutputFormat proxied for writing by PTOF in the same thread, which is a HCat
usecase (using HCatMultiOutputFormat) but not something which is a usecase for hive commandline
or even HS2 (since even in multiwrite cases, since a separate process in the DAG will be the
one using PTOF for writing))

> HCatalog should use getHiveRecordWriter rather than getRecordWriter
> -------------------------------------------------------------------
>
>                 Key: HIVE-4329
>                 URL: https://issues.apache.org/jira/browse/HIVE-4329
>             Project: Hive
>          Issue Type: Bug
>          Components: HCatalog, Serializers/Deserializers
>    Affects Versions: 0.14.0
>         Environment: discovered in Pig, but it looks like the root cause impacts all
non-Hive users
>            Reporter: Sean Busbey
>            Assignee: David Chen
>         Attachments: HIVE-4329.0.patch, HIVE-4329.1.patch, HIVE-4329.2.patch, HIVE-4329.3.patch,
HIVE-4329.4.patch, HIVE-4329.5.patch
>
>
> Attempting to write to a HCatalog defined table backed by the AvroSerde fails with the
following stacktrace:
> {code}
> java.lang.ClassCastException: org.apache.hadoop.io.NullWritable cannot be cast to org.apache.hadoop.io.LongWritable
> 	at org.apache.hadoop.hive.ql.io.avro.AvroContainerOutputFormat$1.write(AvroContainerOutputFormat.java:84)
> 	at org.apache.hcatalog.mapreduce.FileRecordWriterContainer.write(FileRecordWriterContainer.java:253)
> 	at org.apache.hcatalog.mapreduce.FileRecordWriterContainer.write(FileRecordWriterContainer.java:53)
> 	at org.apache.hcatalog.pig.HCatBaseStorer.putNext(HCatBaseStorer.java:242)
> 	at org.apache.hcatalog.pig.HCatStorer.putNext(HCatStorer.java:52)
> 	at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigOutputFormat$PigRecordWriter.write(PigOutputFormat.java:139)
> 	at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigOutputFormat$PigRecordWriter.write(PigOutputFormat.java:98)
> 	at org.apache.hadoop.mapred.MapTask$NewDirectOutputCollector.write(MapTask.java:559)
> 	at org.apache.hadoop.mapreduce.task.TaskInputOutputContextImpl.write(TaskInputOutputContextImpl.java:85)
> {code}
> The proximal cause of this failure is that the AvroContainerOutputFormat's signature
mandates a LongWritable key and HCat's FileRecordWriterContainer forces a NullWritable. I'm
not sure of a general fix, other than redefining HiveOutputFormat to mandate a WritableComparable.
> It looks like accepting WritableComparable is what's done in the other Hive OutputFormats,
and there's no reason AvroContainerOutputFormat couldn't also be changed, since it's ignoring
the key. That way fixing things so FileRecordWriterContainer can always use NullWritable could
get spun into a different issue?
> The underlying cause for failure to write to AvroSerde tables is that AvroContainerOutputFormat
doesn't meaningfully implement getRecordWriter, so fixing the above will just push the failure
into the placeholder RecordWriter.



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