In 0.10 you should have to have bag -> tuple -> elments
2012/7/17 Yang <teddyyyy...@gmail.com>
> ok, found the issue,
>
> now I do not create an explicit FieldSchema for the inside tuple Schema,
> but directly insert the tuple schema into
> the bag. then it works.
>
> this is indeed some difference between 081 and 0.10, cuz the original works
> on 0.10, and the new one only works on 0.8.1
>
> On Tue, Jul 17, 2012 at 4:59 PM, Yang <teddyyyy...@gmail.com> wrote:
>
> > I created a Udf that returns a Bag of Tuples. the syntax is all fine,
> but
> > when I run it in pig,
> > Pig gives error:
> > 2/07/17 16:51:58 INFO jvm.JvmMetrics: Cannot initialize JVM Metrics with
> > processName=JobTracker, sessionId= - already initialized
> > 12/07/17 16:51:58 WARN mapred.LocalJobRunner: job_local_0001
> > java.lang.ClassCastException: java.lang.String cannot be cast to
> > org.apache.pig.data.Tuple
> > at
> >
> org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POProject.getNext(POProject.java:392)
> > at
> >
> org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.processPlan(POForEach.java:342)
> > at
> >
> org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.getNext(POForEach.java:290)
> > at
> >
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.runPipeline(PigMapBase.java:237)
> > at
> >
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.map(PigMapBase.java:232)
> > at
> >
> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.map(PigMapBase.java:53)
> > at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
> > at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:621)
> > at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305)
> > at
> > org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:177)
> > 12/07/17 16:51:58 INFO mapReduceLayer.MapReduceLauncher: HadoopJobId:
> > job_local_0001
> >
> >
> >
> > it looks that the returned value is wrong somehow. but I checked the
> > outputSchema() method, and it is exactly the same as
> > online docs. where am I wrong?
> > ---- this is pig 0.8.1 . I posted a question about 1 month ago,
> > stating that 0.8.1 FLATTEN(bag_of_tuples) behavior is different from
> > 0.10.0, in that
> > it keeps the enclosing tuple, while 0.10.0 strips it and places the
> fields
> > at the root level.
> >
> >
> >
> > Thanks!
> > yang
> >
> > ///// DemoUdf.java
> >
> > import java.io.IOException;
> >
> > import org.apache.pig.EvalFunc;
> > import org.apache.pig.data.DataBag;
> > import org.apache.pig.data.DataType;
> > import org.apache.pig.data.DefaultDataBag;
> > import org.apache.pig.data.DefaultTuple;
> > import org.apache.pig.data.Tuple;
> > import org.apache.pig.impl.logicalLayer.FrontendException;
> > import org.apache.pig.impl.logicalLayer.schema.Schema;
> >
> > public class DemoUdf extends EvalFunc<DataBag> {
> >
> > @Override
> > public DataBag exec(Tuple args) throws IOException {
> >
> > Tuple t1 = new DefaultTuple();
> > t1.append("xx");
> > t1.append("yy");
> > Tuple t2 = new DefaultTuple();
> > t2.append("xxx");
> > t2.append("yyy");
> > DataBag b = new DefaultDataBag();
> > b.add(t1);
> > b.add(t2);
> > return b;
> > }
> >
> > // schema is bagContent:bag{bagContentTuple:tuple(x, y)}
> > @Override
> > public Schema outputSchema(Schema input) {
> > try {
> >
> > Schema insideTuple = new Schema();// this is a tuple
> > insideTuple.add(new Schema.FieldSchema("x", DataType.CHARARRAY));
> > insideTuple.add(new Schema.FieldSchema("y", DataType.CHARARRAY));
> > Schema out = new Schema();
> > out.add(new Schema.FieldSchema("bagContent", bagOfTuples("bagContent",
> > insideTuple), DataType.BAG));
> > return out;
> > } catch (FrontendException e) {
> > e.printStackTrace();
> > return null;
> > }
> > }
> >
> > private Schema bagOfTuples(String bagName, Schema tupleSchema) throws
> > FrontendException {
> > Schema bagSchema = new Schema();
> > // the name does not really matter here, you will see it only on describe
> > output
> > bagSchema.add(new Schema.FieldSchema(bagName + "Tuple", tupleSchema,
> > DataType.TUPLE ));
> >
> > return bagSchema;
> > }
> >
> > }
> >
> >
> >
> >
> >
> >
> //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> > /// src/test/java/DemoTest.java
> >
> > import org.apache.pig.pigunit.PigTest;
> > import org.junit.Test;
> >
> > public class DemoTest {
> > @Test
> > public void blah() {}
> > @Test
> > public void testSimple() throws Exception {
> >
> >
> > PigTest test = new PigTest("src/test/resources/test_demo.pig");
> > // sample input data schema
> > // x : bag{(vertex:int, cliques:bag{tuple(id:int, privateId:int)})
> }
> >
> > String [] inputData = { "1" };
> >
> >
> > String [] expectedOutput = { "({xxx,yyy})"};
> >
> >
> > // don't really verify anything, too long
> > test.assertOutput("inputdata", inputData, "tuples", expectedOutput);
> >
> > }
> >
> > }
> > /////////////////////////////////////////////////////////////////
> >
> >
> > /// src/test/resources/test_demo.pig
> >
> > DEFINE demo DemoUdf();
> >
> > inputdata = load 'src/test/resources/test_demo.pig' as (x:chararray);
> > tuples = FOREACH inputdata GENERATE FLATTEN(demo(1)) as kkk;
> >
> > tuples = FOREACH tuples GENERATE $0;
> > STORE tuples INTO 'fake_output';
> >
> >
> >
> >
> >
>
