You are viewing a plain text version of this content. The canonical link for it is here.
Posted to commits@crunch.apache.org by ma...@apache.org on 2012/09/30 21:34:34 UTC
git commit: CRUNCH-80: Remove old markdown documentation.
Updated Branches:
refs/heads/master 37a7fac13 -> 0083239b2
CRUNCH-80: Remove old markdown documentation.
We use the Apache CMS to maintain our site.
Source code and documentation of the site has moved to Subversion.
Project: http://git-wip-us.apache.org/repos/asf/incubator-crunch/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-crunch/commit/0083239b
Tree: http://git-wip-us.apache.org/repos/asf/incubator-crunch/tree/0083239b
Diff: http://git-wip-us.apache.org/repos/asf/incubator-crunch/diff/0083239b
Branch: refs/heads/master
Commit: 0083239b2fb92bf1238edd0f7c9529d5fe77813a
Parents: 37a7fac
Author: Matthias Friedrich <ma...@mafr.de>
Authored: Sat Sep 29 10:13:06 2012 +0200
Committer: Matthias Friedrich <ma...@mafr.de>
Committed: Sun Sep 30 21:32:18 2012 +0200
----------------------------------------------------------------------
crunch-examples/src/site/markdown/index.md | 20 --
crunch-scrunch/src/site/markdown/index.md | 20 --
crunch/src/site/markdown/index.md | 20 --
pom.xml | 5 -
src/site/markdown/future-work.md | 29 ---
src/site/markdown/index.md | 49 -----
src/site/markdown/intro.md | 214 -----------------------
src/site/markdown/pipelines.md | 103 -----------
src/site/markdown/scrunch.md | 89 ----------
9 files changed, 0 insertions(+), 549 deletions(-)
----------------------------------------------------------------------
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/crunch-examples/src/site/markdown/index.md
----------------------------------------------------------------------
diff --git a/crunch-examples/src/site/markdown/index.md b/crunch-examples/src/site/markdown/index.md
deleted file mode 100644
index 838e3ae..0000000
--- a/crunch-examples/src/site/markdown/index.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
-http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-# Apache Crunch - Examples
----
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/crunch-scrunch/src/site/markdown/index.md
----------------------------------------------------------------------
diff --git a/crunch-scrunch/src/site/markdown/index.md b/crunch-scrunch/src/site/markdown/index.md
deleted file mode 100644
index 32a9279..0000000
--- a/crunch-scrunch/src/site/markdown/index.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
-http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-# Scrunch - A Scala Wrapper for Crunch
----
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/crunch/src/site/markdown/index.md
----------------------------------------------------------------------
diff --git a/crunch/src/site/markdown/index.md b/crunch/src/site/markdown/index.md
deleted file mode 100644
index a89c404..0000000
--- a/crunch/src/site/markdown/index.md
+++ /dev/null
@@ -1,20 +0,0 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
-http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-# Apache Crunch - Core
----
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/pom.xml
----------------------------------------------------------------------
diff --git a/pom.xml b/pom.xml
index e048e08..d3bf8c6 100644
--- a/pom.xml
+++ b/pom.xml
@@ -523,11 +523,6 @@ under the License.
<artifactId>wagon-ssh</artifactId>
<version>1.0</version>
</dependency>
- <dependency>
- <groupId>org.apache.maven.doxia</groupId>
- <artifactId>doxia-module-markdown</artifactId>
- <version>1.3</version>
- </dependency>
</dependencies>
<configuration>
<inputEncoding>UTF-8</inputEncoding>
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/src/site/markdown/future-work.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/future-work.md b/src/site/markdown/future-work.md
deleted file mode 100644
index bf1e16f..0000000
--- a/src/site/markdown/future-work.md
+++ /dev/null
@@ -1,29 +0,0 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
-http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-# Current Limitations and Future Work
----
-
-This section contains an almost certainly incomplete list of known limitations of Crunch and plans for future work.
-
-* We would like to have easy support for reading and writing data from/to HCatalog.
-* The decision of how to split up processing tasks between dependent MapReduce jobs is very naiive right now- we simply
-delegate all of the work to the reduce stage of the predecessor job. We should take advantage of information about the
-expected size of different PCollections to optimize this processing.
-* The Crunch optimizer does not yet merge different groupByKey operations that run over the same input data into a single
-MapReduce job. Implementing this optimization will provide a major performance benefit for a number of problems.
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/src/site/markdown/index.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/index.md b/src/site/markdown/index.md
deleted file mode 100644
index f5862ce..0000000
--- a/src/site/markdown/index.md
+++ /dev/null
@@ -1,49 +0,0 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
-http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-# Apache Crunch - Simple and Efficient MapReduce Pipelines
----
-
-> *Apache Crunch (incubating)* is a Java library for writing, testing, and
-> running MapReduce pipelines, based on Google\'s FlumeJava. Its goal is to make
-> pipelines that are composed of many user-defined functions simple to write,
-> easy to test, and efficient to run.
-
----
-
-Running on top of [Hadoop MapReduce](http://hadoop.apache.org/mapreduce/), Apache
-Crunch provides a simple Java API for tasks like joining and data aggregation
-that are tedious to implement on plain MapReduce. For Scala users, there is also
-Scrunch, an idiomatic Scala API to Crunch.
-
-## Documentation
-
- * [Introduction to Apache Crunch](intro.html)
- * [Introduction to Scrunch](scrunch.html)
- * [Current Limitations and Future Work](future-work.html)
-
-## Disclaimer
-
-Apache Crunch is an effort undergoing incubation at [The Apache Software Foundation
-(ASF)](http://apache.org/) sponsored by the [Apache Incubator PMC](http://incubator.apache.org/).
-Incubation is required of all newly accepted projects until a further review
-indicates that the infrastructure, communications, and decision making process
-have stabilized in a manner consistent with other successful ASF projects.
-While incubation status is not necessarily a reflection of the completeness or
-stability of the code, it does indicate that the project has yet to be fully
-endorsed by the ASF.
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/src/site/markdown/intro.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/intro.md b/src/site/markdown/intro.md
deleted file mode 100644
index 0a8089b..0000000
--- a/src/site/markdown/intro.md
+++ /dev/null
@@ -1,214 +0,0 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
-http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-# Introduction to Apache Crunch
----
-
-## Build and Installation
-
-To use Crunch you first have to build the source code using Maven and install
-it in your local repository:
-
- mvn clean install
-
-This also runs the integration test suite which will take a while. Afterwards
-you can run the bundled example applications:
-
- hadoop jar examples/target/crunch-examples-*-job.jar org.apache.crunch.examples.WordCount <inputfile> <outputdir>
-
-
-## High Level Concepts
-
-### Data Model and Operators
-
-Crunch is centered around three interfaces that represent distributed datasets: `PCollection<T>`, `PTable<K, V>`, and `PGroupedTable<K, V>`.
-
-A `PCollection<T>` represents a distributed, unordered collection of elements of type T. For example, we represent a text file in Crunch as a
-`PCollection<String>` object. PCollection provides a method, `parallelDo`, that applies a function to each element in a PCollection in parallel,
-and returns a new PCollection as its result.
-
-A `PTable<K, V>` is a sub-interface of PCollection that represents a distributed, unordered multimap of its key type K to its value type V.
-In addition to the parallelDo operation, PTable provides a `groupByKey` operation that aggregates all of the values in the PTable that
-have the same key into a single record. It is the groupByKey operation that triggers the sort phase of a MapReduce job.
-
-The result of a groupByKey operation is a `PGroupedTable<K, V>` object, which is a distributed, sorted map of keys of type K to an Iterable
-collection of values of type V. In addition to parallelDo, the PGroupedTable provides a `combineValues` operation, which allows for
-a commutative and associative aggregation operator to be applied to the values of the PGroupedTable instance on both the map side and the
-reduce side of a MapReduce job.
-
-Finally, PCollection, PTable, and PGroupedTable all support a `union` operation, which takes a series of distinct PCollections and treats
-them as a single, virtual PCollection. The union operator is required for operations that combine multiple inputs, such as cogroups and
-joins.
-
-### Pipeline Building and Execution
-
-Every Crunch pipeline starts with a `Pipeline` object that is used to coordinate building the pipeline and executing the underlying MapReduce
-jobs. For efficiency, Crunch uses lazy evaluation, so it will only construct MapReduce jobs from the different stages of the pipelines when
-the Pipeline object\'s `run` or `done` methods are called.
-
-## A Detailed Example
-
-Here is the classic WordCount application using Crunch:
-
- import org.apache.crunch.DoFn;
- import org.apache.crunch.Emitter;
- import org.apache.crunch.PCollection;
- import org.apache.crunch.PTable;
- import org.apache.crunch.Pipeline;
- import org.apache.crunch.impl.mr.MRPipeline;
- import org.apache.crunch.lib.Aggregate;
- import org.apache.crunch.types.writable.Writables;
-
- public class WordCount {
- public static void main(String[] args) throws Exception {
- Pipeline pipeline = new MRPipeline(WordCount.class);
- PCollection<String> lines = pipeline.readTextFile(args[0]);
-
- PCollection<String> words = lines.parallelDo("my splitter", new DoFn<String, String>() {
- public void process(String line, Emitter<String> emitter) {
- for (String word : line.split("\\s+")) {
- emitter.emit(word);
- }
- }
- }, Writables.strings());
-
- PTable<String, Long> counts = Aggregate.count(words);
-
- pipeline.writeTextFile(counts, args[1]);
- pipeline.run();
- }
- }
-
-Let\'s walk through the example line by line.
-
-### Step 1: Creating a Pipeline and referencing a text file
-
-The `MRPipeline` implementation of the Pipeline interface compiles the individual stages of a
-pipeline into a series of MapReduce jobs. The MRPipeline constructor takes a class argument
-that is used to tell Hadoop where to find the code that is used in the pipeline execution.
-
-We now need to tell the Pipeline about the inputs it will be consuming. The Pipeline interface
-defines a `readTextFile` method that takes in a String and returns a PCollection of Strings.
-In addition to text files, Crunch supports reading data from SequenceFiles and Avro container files,
-via the `SequenceFileSource` and `AvroFileSource` classes defined in the org.apache.crunch.io package.
-
-Note that each PCollection is a _reference_ to a source of data- no data is actually loaded into a
-PCollection on the client machine.
-
-### Step 2: Splitting the lines of text into words
-
-Crunch defines a small set of primitive operations that can be composed in order to build complex data
-pipelines. The first of these primitives is the `parallelDo` function, which applies a function (defined
-by a subclass of `DoFn`) to every record in a PCollection, and returns a new PCollection that contains
-the results.
-
-The first argument to parallelDo is a string that is used to identify this step in the pipeline. When
-a pipeline is composed into a series of MapReduce jobs, it is often the case that multiple stages will
-run within the same Mapper or Reducer. Having a string that identifies each processing step is useful
-for debugging errors that occur in a running pipeline.
-
-The second argument to parallelDo is an anonymous subclass of DoFn. Each DoFn subclass must override
-the `process` method, which takes in a record from the input PCollection and an `Emitter` object that
-may have any number of output values written to it. In this case, our DoFn splits each lines up into
-words, using a blank space as a separator, and emits the words from the split to the output PCollection.
-
-The last argument to parallelDo is an instance of the `PType` interface, which specifies how the data
-in the output PCollection is serialized. While Crunch takes advantage of Java Generics to provide
-compile-time type safety, the generic type information is not available at runtime. Crunch needs to know
-how to map the records stored in each PCollection into a Hadoop-supported serialization format in order
-to read and write data to disk. Two serialization implementations are supported in crunch via the
-`PTypeFamily` interface: a Writable-based system that is defined in the org.apache.crunch.types.writable
-package, and an Avro-based system that is defined in the org.apache.crunch.types.avro package. Each
-implementation provides convenience methods for working with the common PTypes (Strings, longs, bytes, etc.)
-as well as utility methods for creating PTypes from existing Writable classes or Avro schemas.
-
-### Step 3: Counting the words
-
-Out of Crunch\'s simple primitive operations, we can build arbitrarily complex chains of operations in order
-to perform higher-level operations, like aggregations and joins, that can work on any type of input data.
-Let\'s look at the implementation of the `Aggregate.count` function:
-
- package org.apache.crunch.lib;
-
- import org.apache.crunch.CombineFn;
- import org.apache.crunch.MapFn;
- import org.apache.crunch.PCollection;
- import org.apache.crunch.PGroupedTable;
- import org.apache.crunch.PTable;
- import org.apache.crunch.Pair;
- import org.apache.crunch.types.PTypeFamily;
-
- public class Aggregate {
-
- private static class Counter<S> extends MapFn<S, Pair<S, Long>> {
- public Pair<S, Long> map(S input) {
- return Pair.of(input, 1L);
- }
- }
-
- public static <S> PTable<S, Long> count(PCollection<S> collect) {
- PTypeFamily tf = collect.getTypeFamily();
-
- // Create a PTable from the PCollection by mapping each element
- // to a key of the PTable with the value equal to 1L
- PTable<S, Long> withCounts = collect.parallelDo("count:" + collect.getName(),
- new Counter<S>(), tf.tableOf(collect.getPType(), tf.longs()));
-
- // Group the records of the PTable based on their key.
- PGroupedTable<S, Long> grouped = withCounts.groupByKey();
-
- // Sum the 1L values associated with the keys to get the
- // count of each element in this PCollection, and return it
- // as a PTable so that it may be processed further or written
- // out for storage.
- return grouped.combineValues(CombineFn.<S>SUM_LONGS());
- }
- }
-
-First, we get the PTypeFamily that is associated with the PType for the collection. The
-call to parallelDo converts each record in this PCollection into a Pair of the input record
-and the number one by extending the `MapFn` convenience subclass of DoFn, and uses the
-`tableOf` method of the PTypeFamily to specify that the returned PCollection should be a
-PTable instance, with the key being the PType of the PCollection and the value being the Long
-implementation for this PTypeFamily.
-
-The next line features the second of Crunch\'s four operations, `groupByKey`. The groupByKey
-operation may only be applied to a PTable, and returns an instance of the `PGroupedTable`
-interface, which references the grouping of all of the values in the PTable that have the same key.
-The groupByKey operation is what triggers the reduce phase of a MapReduce within Crunch.
-
-The last line in the function returns the output of the third of Crunch\'s four operations,
-`combineValues`. The combineValues operator takes a `CombineFn` as an argument, which is a
-specialized subclass of DoFn that operates on an implementation of Java\'s Iterable interface. The
-use of combineValues (as opposed to parallelDo) signals to Crunch that the CombineFn may be used to
-aggregate values for the same key on the map side of a MapReduce job as well as the reduce side.
-
-### Step 4: Writing the output and running the pipeline
-
-The Pipeline object also provides a `writeTextFile` convenience method for indicating that a
-PCollection should be written to a text file. There are also output targets for SequenceFiles and
-Avro container files, available in the org.apache.crunch.io package.
-
-After you are finished constructing a pipeline and specifying the output destinations, call the
-pipeline\'s blocking `run` method in order to compile the pipeline into one or more MapReduce
-jobs and execute them.
-
-
-## More Information
-
-[Writing Your Own Pipelines](pipelines.html)
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/src/site/markdown/pipelines.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/pipelines.md b/src/site/markdown/pipelines.md
deleted file mode 100644
index 6fea519..0000000
--- a/src/site/markdown/pipelines.md
+++ /dev/null
@@ -1,103 +0,0 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
-http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-# Writing Your Own Pipelines
----
-
-This section discusses the different steps of creating your own Crunch pipelines in more detail.
-
-## Writing a DoFn
-
-The DoFn class is designed to keep the complexity of the MapReduce APIs out of your way when you
-don\'t need them while still keeping them accessible when you do.
-
-### Serialization
-
-First, all DoFn instances are required to be `java.io.Serializable`. This is a key aspect of Crunch\'s design:
-once a particular DoFn is assigned to the Map or Reduce stage of a MapReduce job, all of the state
-of that DoFn is serialized so that it may be distributed to all of the nodes in the Hadoop cluster that
-will be running that task. There are two important implications of this for developers:
-
-1. All member values of a DoFn must be either serializable or marked as `transient`.
-2. All anonymous DoFn instances must be defined in a static method or in a class that is itself serializable.
-
-Because sometimes you will need to work with non-serializable objects inside of a DoFn, every DoFn provides an
-`initialize` method that is called before the `process` method is ever called so that any initialization tasks,
-such as creating a non-serializable member variable, can be performed before processing begins. Similarly, all
-DoFn instances have a `cleanup` method that may be called after processing has finished to perform any required
-cleanup tasks.
-
-### Scale Factor
-
-The DoFn class defines a `scaleFactor` method that can be used to signal to the MapReduce compiler that a particular
-DoFn implementation will yield an output PCollection that is larger (scaleFactor > 1) or smaller (0 < scaleFactor < 1)
-than the input PCollection it is applied to. The compiler may use this information to determine how to optimally
-split processing tasks between the Map and Reduce phases of dependent MapReduce jobs.
-
-### Other Utilities
-
-The DoFn base class provides convenience methods for accessing the `Configuration` and `Counter` objects that
-are associated with a MapReduce stage, so that they may be accessed during initialization, processing, and cleanup.
-
-### Performing Cogroups and Joins
-
-In Crunch, cogroups and joins are performed on PTable instances that have the same key type. This section walks through
-the basic flow of a cogroup operation, explaining how this higher-level operation is composed of Crunch\'s four primitives.
-In general, these common operations are provided as part of the core Crunch library or in extensions, you do not need
-to write them yourself. But it can be useful to understand how they work under the covers.
-
-Assume we have a `PTable<K, U>` named "a" and a different `PTable<K, V>` named "b" that we would like to combine into a
-single `PTable<K, Pair<Collection<U>, Collection<V>>>`. First, we need to apply parallelDo operations to a and b that
-convert them into the same Crunch type, `PTable<K, Pair<U, V>>`:
-
- // Perform the "tagging" operation as a parallelDo on PTable a
- PTable<K, Pair<U, V>> aPrime = a.parallelDo("taga", new MapFn<Pair<K, U>, Pair<K, Pair<U, V>>>() {
- public Pair<K, Pair<U, V>> map(Pair<K, U> input) {
- return Pair.of(input.first(), Pair.of(input.second(), null));
- }
- }, tableOf(a.getKeyType(), pair(a.getValueType(), b.getValueType())));
-
- // Perform the "tagging" operation as a parallelDo on PTable b
- PTable<K, Pair<U, V>> bPrime = b.parallelDo("tagb", new MapFn<Pair<K, V>, Pair<K, Pair<U, V>>>() {
- public Pair<K, Pair<U, V>> map(Pair<K, V> input) {
- return Pair.of(input.first(), Pair.of(null, input.second()));
- }
- }, tableOf(a.getKeyType(), pair(a.getValueType(), b.getValueType())));
-
-Once the input PTables are tagged into a single type, we can apply the union operation to create a single PTable
-reference that includes both of the tagged PTables and then group the unioned PTable by the common key:
-
- PTable<K, Pair<U, V>> both = aPrime.union(bPrime);
- PGroupedTable<K, Pair<U, V>> grouped = both.groupByKey();
-
-The grouping operation will create an `Iterable<Pair<U, V>>` which we can then convert to a `Pair<Collection<U>, Collection<V>>`:
-
- grouped.parallelDo("cogroup", new MapFn<Pair<K, Iterable<Pair<U, V>>>, Pair<K, Pair<Collection<U>, Collection<V>>>>() {
- public Pair<K, Pair<Collection<U>, Collection<V>>> map(Pair<K, Iterable<Pair<U, V>>> input) {
- Collection<U> uValues = new ArrayList<U>();
- Collection<V> vValues = new ArrayList<V>();
- for (Pair<U, V> pair : input.second()) {
- if (pair.first() != null) {
- uValues.add(pair.first());
- } else {
- vValues.add(pair.second());
- }
- }
- return Pair.of(input.first(), Pair.of(uValues, vValues));
- },
- }, tableOf(grouped.getKeyType(), pair(collections(a.getValueType()), collections(b.getValueType()))));
http://git-wip-us.apache.org/repos/asf/incubator-crunch/blob/0083239b/src/site/markdown/scrunch.md
----------------------------------------------------------------------
diff --git a/src/site/markdown/scrunch.md b/src/site/markdown/scrunch.md
deleted file mode 100644
index 324b88a..0000000
--- a/src/site/markdown/scrunch.md
+++ /dev/null
@@ -1,89 +0,0 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements. See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership. The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License. You may obtain a copy of the License at
-
-http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied. See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-# Scrunch - A Scala Wrapper for Apache Crunch
----
-
-## Introduction
-
-Scrunch is an experimental Scala wrapper for Crunch, based on the same ideas as the
-[Cascade](http://days2011.scala-lang.org/node/138/282) project at Google, which created
-a Scala wrapper for FlumeJava.
-
-## Why Scala?
-
-In many ways, Scala is the perfect language for writing Crunch pipelines. Scala supports
-a mixture of functional and object-oriented programming styles and has powerful type-inference
-capabilities, allowing us to create complex pipelines using very few keystrokes. Here is
-the Scrunch analogue of the classic WordCount problem:
-
- import org.apache.crunch.io.{From => from}
- import org.apache.crunch.scrunch._
- import org.apache.crunch.scrunch.Conversions_ # For implicit type conversions
-
- class WordCountExample {
- val pipeline = new Pipeline[WordCountExample]
-
- def wordCount(fileName: String) = {
- pipeline.read(from.textFile(fileName))
- .flatMap(_.toLowerCase.split("\\W+"))
- .filter(!_.isEmpty())
- .count
- }
- }
-
-The Scala compiler can infer the return type of the flatMap function as an Array[String], and
-the Scrunch wrapper uses the type inference mechanism to figure out how to serialize the
-data between the Map and Reduce stages. Here\'s a slightly more complex example, in which we
-get the word counts for two different files and compute the deltas of how often different
-words occur, and then only returns the words where the first file had more occurrences then
-the second:
-
- class WordCountExample {
- def wordGt(firstFile: String, secondFile: String) = {
- wordCount(firstFile).cogroup(wordCount(secondFile))
- .map((k, v) => (k, (v._1.sum - v._2.sum)))
- .filter((k, v) => v > 0).map((k, v) => k)
- }
- }
-
-Note that all of the functions are using Scala Tuples, not Crunch Tuples. Under the covers,
-Scrunch uses Scala\'s implicit type conversion mechanism to transparently convert data from the
-Crunch format to the Scala format and back again.
-
-## Materializing Job Outputs
-
-Scrunch also incorporates Crunch\'s materialize functionality, which allows us to easily read
-the output of a Crunch pipeline into the client:
-
- class WordCountExample {
- def hasHamlet = wordGt("shakespeare.txt", "maugham.txt").materialize.exists(_ == "hamlet")
- }
-
-## Notes and Thanks
-
-Scrunch is alpha-quality code, written by someone who was learning Scala on the fly. There will be bugs,
-rough edges, and non-idiomatic Scala usage all over the place. This will improve with time, and we welcome
-contributions from Scala experts who are interested in helping us make Scrunch into a first-class project.
-
-Scrunch emerged out of conversations with [Dmitriy Ryaboy](http://twitter.com/#!/squarecog),
-[Oscar Boykin](http://twitter.com/#!/posco), and [Avi Bryant](http://twitter.com/#!/avibryant) from Twitter.
-Many thanks to them for their feedback, guidance, and encouragement. We are also grateful to
-[Matei Zaharia](http://twitter.com/#!/matei_zaharia), whose [Spark Project](http://www.spark-project.org/)
-inspired much of our implementation and was kind enough to loan us the ClosureCleaner implementation
-Spark developed for use in Scrunch.