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From "Russell Jurney (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (PIG-1748) Add load/store function AvroStorage for avro data
Date Wed, 07 Dec 2011 07:46:45 GMT

     [ https://issues.apache.org/jira/browse/PIG-1748?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Russell Jurney updated PIG-1748:
--------------------------------

    Attachment: AvroStorageUtils-bagfix.patch

This patch is a fix for a bug for persisting bags of tuples via AvroStorage.

The script that alerted me to a bug is:

messages = LOAD '/tmp/messages.avro' USING AvroStorage();
user_groups = GROUP messages by user_id;
per_user = FOREACH user_groups {                
    sorted = ORDER messages BY message_id DESC;     
    GENERATE group AS user_id, sorted AS messages;
}
DESCRIBE per_user
> per_user: {user_id: int,messages: {(message_id: int,topic: chararray,user_id: int)}}
STORE per_user INTO '/tmp/per_user.avro' USING AvroStorage();

The error is:

Pig Stack Trace
---------------
ERROR 1002: Unable to store alias per_user

org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1002: Unable to store alias per_user
	at org.apache.pig.PigServer$Graph.registerQuery(PigServer.java:1596)
	at org.apache.pig.PigServer.registerQuery(PigServer.java:584)
	at org.apache.pig.tools.grunt.GruntParser.processPig(GruntParser.java:942)
	at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:386)
	at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:188)
	at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:164)
	at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:67)
	at org.apache.pig.Main.run(Main.java:487)
	at org.apache.pig.Main.main(Main.java:108)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
Caused by: java.lang.NullPointerException
	at org.apache.pig.piggybank.storage.avro.AvroStorageUtils.isTupleWrapper(AvroStorageUtils.java:327)
	at org.apache.pig.piggybank.storage.avro.PigSchema2Avro.convert(PigSchema2Avro.java:82)
	at org.apache.pig.piggybank.storage.avro.PigSchema2Avro.convert(PigSchema2Avro.java:105)
	at org.apache.pig.piggybank.storage.avro.PigSchema2Avro.convertRecord(PigSchema2Avro.java:151)
	at org.apache.pig.piggybank.storage.avro.PigSchema2Avro.convert(PigSchema2Avro.java:62)
	at org.apache.pig.piggybank.storage.avro.AvroStorage.checkSchema(AvroStorage.java:502)
	at org.apache.pig.newplan.logical.rules.InputOutputFileValidator$InputOutputFileVisitor.visit(InputOutputFileValidator.java:65)
	at org.apache.pig.newplan.logical.relational.LOStore.accept(LOStore.java:77)
	at org.apache.pig.newplan.DepthFirstWalker.depthFirst(DepthFirstWalker.java:64)
	at org.apache.pig.newplan.DepthFirstWalker.depthFirst(DepthFirstWalker.java:66)
	at org.apache.pig.newplan.DepthFirstWalker.depthFirst(DepthFirstWalker.java:66)
	at org.apache.pig.newplan.DepthFirstWalker.depthFirst(DepthFirstWalker.java:66)
	at org.apache.pig.newplan.DepthFirstWalker.depthFirst(DepthFirstWalker.java:66)
	at org.apache.pig.newplan.DepthFirstWalker.walk(DepthFirstWalker.java:53)
	at org.apache.pig.newplan.PlanVisitor.visit(PlanVisitor.java:50)
	at org.apache.pig.newplan.logical.rules.InputOutputFileValidator.validate(InputOutputFileValidator.java:45)
	at org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.compile(HExecutionEngine.java:292)
	at org.apache.pig.PigServer.compilePp(PigServer.java:1360)
	at org.apache.pig.PigServer.executeCompiledLogicalPlan(PigServer.java:1297)
	at org.apache.pig.PigServer.execute(PigServer.java:1286)
	at org.apache.pig.PigServer.access$400(PigServer.java:125)
	at org.apache.pig.PigServer$Graph.registerQuery(PigServer.java:1591)
	... 13 more

                
> Add load/store function AvroStorage for avro data
> -------------------------------------------------
>
>                 Key: PIG-1748
>                 URL: https://issues.apache.org/jira/browse/PIG-1748
>             Project: Pig
>          Issue Type: Improvement
>          Components: impl
>            Reporter: lin guo
>            Assignee: lin guo
>             Fix For: 0.9.0
>
>         Attachments: AvroStorageUtils-bagfix.patch, PIG-1748-2.patch, PIG-1748-3.patch,
avro_storage.patch, avro_test_files.tar.gz
>
>
> We want to use Pig to process arbitrary Avro data and store results as Avro files. AvroStorage()
extends two PigFuncs: LoadFunc and StoreFunc. 
> Due to discrepancies of Avro and Pig data models, AvroStorage has:
> 1. Limited support for "record": we do not support recursively defined record because
the number of fields in such records is data dependent.
> 2. Limited support for "union": we only accept nullable union like ["null", "some-type"].
> For simplicity, we also make the following assumptions:
> If the input directory is a leaf directory, then we assume Avro data files in it have
the same schema;
> If the input directory contains sub-directories, then we assume Avro data files in all
sub-directories have the same schema.
> AvroStorage takes no input parameters when used as a LoadFunc (except for "debug [debug-level]").

> Users can provide parameters to AvroStorage when used as a StoreFunc. If they don't,
Avro schema of output data is derived from its 
> Pig schema.
> Detailed documentation can be found in http://linkedin.jira.com/wiki/display/HTOOLS/AvroStorage+-+Pig+support+for+Avro+data

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