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From "Josh Wills (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CRUNCH-247) Planner should take advantage of to-be-materialized outputs during planning
Date Wed, 07 Aug 2013 03:29:48 GMT
Josh Wills created CRUNCH-247:
---------------------------------

             Summary: Planner should take advantage of to-be-materialized outputs during planning
                 Key: CRUNCH-247
                 URL: https://issues.apache.org/jira/browse/CRUNCH-247
             Project: Crunch
          Issue Type: Bug
          Components: Core
            Reporter: Josh Wills
            Assignee: Josh Wills
             Fix For: 0.8.0


In the following pipeline, the Crunch planner will rerun the "op1" step in two independent
map-only jobs, instead of running a single job that executes the op1 step followed by a subsequent
job that consumes that output and runs the op2 step:

     PCollection<String> in = p.read(From.textFile(inputPath));
     PTable<String, String> op = in.parallelDo("op1", new DoFn<String, Pair<String,
String>>() {
      @Override
      public void process(String input, Emitter<Pair<String, String>> emitter)
{
        if (input.length() > 5) {
          emitter.emit(Pair.of(input.substring(0, 3), input));
        }
      } 
     }, tableOf(strings(), strings()));
     
     SourceTarget src = (SourceTarget)((MaterializableIterable<Pair<String, String>>)
op.materialize()).getSource();
     
     op = op.parallelDo("op2", IdentityFn.<Pair<String,String>>getInstance(),
tableOf(strings(), strings()),
         ParallelDoOptions.builder().sourceTargets(src).build());
     
     PCollection<String> output = op.values();
     output.write(To.textFile(out));

The planner should be able to take advantage of the materialized output from op1 to not re-run
that step in the op2 job.

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