Chao Wang updated PIG-1104:

    Status: Patch Available  (was: Open)

> [zebra] Provide streaming support in Zebra.
> -------------------------------------------
>                 Key: PIG-1104
>                 URL: https://issues.apache.org/jira/browse/PIG-1104
>             Project: Pig
>          Issue Type: New Feature
>    Affects Versions: 0.4.0
>            Reporter: Chao Wang
>            Assignee: Chao Wang
>             Fix For: 0.6.0, 0.7.0
>         Attachments: PIG-1104.patch
> Hadoop streaming is very popular among Hadoop users. The main attraction is 
> the simplicity of use. A user can write the application logic in any language 
> and process large amounts of data using Hadoop framework. As more people 
> start to use Zebra to store their data, we expect users would like to run 
> Hadoop streaming scripts to easily process Zebra tables. 
> The following lists a simple example of using Hadoop streaming to access 
> Zebra data. It loads data from foo table using Zebra's TableInputFormat and 
> then writes the data into output using default TextOutputFormat. 
> $ hadoop jar hadoop-streaming.jar -D mapred.reduce.tasks=0 -input foo -output 
> output -mapper 'cat' -inputformat 
> org.apache.hadoop.zebra.mapred.TableInputFormat 
> More detailed, Zebra uses Pig DefaultTuple implementation of Tuple for its 
> records. Currently, when Zebra's TableInputFormat is used for input, the user 
> script sees each line containing " key_if_any\tTuple.toString() ". We plan to 
> generate CSV format representation of our Pig tuples. To this end, we plan to 
> do the following: 
> 1) Derive a sub class ZupleTuple from pig's DefaultTuple class and override 
> its toString() method to present the data into CSV format. 
> 2) On Zebra side, the tuple factory should be changed to create ZebraTuple 
> objects, instead of DefaultTuple objects. 
> Note that we can only support streaming on the input side - ability to use 
> streaming to read data from Zebra tables. For the output side, the streaming 
> support is not feasible, since the streaming mapper or reducer only emits 
> "Text\tText", the output collector has no way of knowing how to convert this 
> to (BytesWritable,Tuple).

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