[SPARK-546] Add full outer join to RDD and DStream.

leftOuterJoin and rightOuterJoin are already implemented.  This patch adds fullOuterJoin.

Author: Aaron Staple <aaron.staple@gmail.com>

Closes #1395 from staple/SPARK-546 and squashes the following commits:

1f5595c [Aaron Staple] Fix python style
7ac0aa9 [Aaron Staple] [SPARK-546] Add full outer join to RDD and DStream.
3b5d137 [Aaron Staple] In JavaPairDStream, make class tag specification in rightOuterJoin consistent with other functions.
31f2956 [Aaron Staple] Fix left outer join documentation comments.

Author: staple

core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala

@@ -469,6 +469,22 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
     fromRDD(joinResult.mapValues{case (v, w) => (JavaUtils.optionToOptional(v), w)})
   }
 
+  /**
+   * Perform a full outer join of `this` and `other`. For each element (k, v) in `this`, the
+   * resulting RDD will either contain all pairs (k, (Some(v), Some(w))) for w in `other`, or
+   * the pair (k, (Some(v), None)) if no elements in `other` have key k. Similarly, for each
+   * element (k, w) in `other`, the resulting RDD will either contain all pairs
+   * (k, (Some(v), Some(w))) for v in `this`, or the pair (k, (None, Some(w))) if no elements
+   * in `this` have key k. Uses the given Partitioner to partition the output RDD.
+   */
+  def fullOuterJoin[W](other: JavaPairRDD[K, W], partitioner: Partitioner)
+  : JavaPairRDD[K, (Optional[V], Optional[W])] = {
+    val joinResult = rdd.fullOuterJoin(other, partitioner)
+    fromRDD(joinResult.mapValues{ case (v, w) =>
+      (JavaUtils.optionToOptional(v), JavaUtils.optionToOptional(w))
+    })
+  }
+
   /**
    * Simplified version of combineByKey that hash-partitions the resulting RDD using the existing
    * partitioner/parallelism level.
@@ -563,6 +579,38 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
     fromRDD(joinResult.mapValues{case (v, w) => (JavaUtils.optionToOptional(v), w)})
   }
 
+  /**
+   * Perform a full outer join of `this` and `other`. For each element (k, v) in `this`, the
+   * resulting RDD will either contain all pairs (k, (Some(v), Some(w))) for w in `other`, or
+   * the pair (k, (Some(v), None)) if no elements in `other` have key k. Similarly, for each
+   * element (k, w) in `other`, the resulting RDD will either contain all pairs
+   * (k, (Some(v), Some(w))) for v in `this`, or the pair (k, (None, Some(w))) if no elements
+   * in `this` have key k. Hash-partitions the resulting RDD using the existing partitioner/
+   * parallelism level.
+   */
+  def fullOuterJoin[W](other: JavaPairRDD[K, W]): JavaPairRDD[K, (Optional[V], Optional[W])] = {
+    val joinResult = rdd.fullOuterJoin(other)
+    fromRDD(joinResult.mapValues{ case (v, w) =>
+      (JavaUtils.optionToOptional(v), JavaUtils.optionToOptional(w))
+    })
+  }
+
+  /**
+   * Perform a full outer join of `this` and `other`. For each element (k, v) in `this`, the
+   * resulting RDD will either contain all pairs (k, (Some(v), Some(w))) for w in `other`, or
+   * the pair (k, (Some(v), None)) if no elements in `other` have key k. Similarly, for each
+   * element (k, w) in `other`, the resulting RDD will either contain all pairs
+   * (k, (Some(v), Some(w))) for v in `this`, or the pair (k, (None, Some(w))) if no elements
+   * in `this` have key k. Hash-partitions the resulting RDD into the given number of partitions.
+   */
+  def fullOuterJoin[W](other: JavaPairRDD[K, W], numPartitions: Int)
+  : JavaPairRDD[K, (Optional[V], Optional[W])] = {
+    val joinResult = rdd.fullOuterJoin(other, numPartitions)
+    fromRDD(joinResult.mapValues{ case (v, w) =>
+      (JavaUtils.optionToOptional(v), JavaUtils.optionToOptional(w))
+    })
+  }
+
   /**
    * Return the key-value pairs in this RDD to the master as a Map.
    */

core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala

@@ -506,6 +506,23 @@ class PairRDDFunctions[K, V](self: RDD[(K, V)])
     }
   }
 
+  /**
+   * Perform a full outer join of `this` and `other`. For each element (k, v) in `this`, the
+   * resulting RDD will either contain all pairs (k, (Some(v), Some(w))) for w in `other`, or
+   * the pair (k, (Some(v), None)) if no elements in `other` have key k. Similarly, for each
+   * element (k, w) in `other`, the resulting RDD will either contain all pairs
+   * (k, (Some(v), Some(w))) for v in `this`, or the pair (k, (None, Some(w))) if no elements
+   * in `this` have key k. Uses the given Partitioner to partition the output RDD.
+   */
+  def fullOuterJoin[W](other: RDD[(K, W)], partitioner: Partitioner)
+      : RDD[(K, (Option[V], Option[W]))] = {
+    this.cogroup(other, partitioner).flatMapValues {
+      case (vs, Seq()) => vs.map(v => (Some(v), None))
+      case (Seq(), ws) => ws.map(w => (None, Some(w)))
+      case (vs, ws) => for (v <- vs; w <- ws) yield (Some(v), Some(w))
+    }
+  }
+
   /**
    * Simplified version of combineByKey that hash-partitions the resulting RDD using the
    * existing partitioner/parallelism level.
@@ -585,6 +602,31 @@ class PairRDDFunctions[K, V](self: RDD[(K, V)])
     rightOuterJoin(other, new HashPartitioner(numPartitions))
   }
 
+  /**
+   * Perform a full outer join of `this` and `other`. For each element (k, v) in `this`, the
+   * resulting RDD will either contain all pairs (k, (Some(v), Some(w))) for w in `other`, or
+   * the pair (k, (Some(v), None)) if no elements in `other` have key k. Similarly, for each
+   * element (k, w) in `other`, the resulting RDD will either contain all pairs
+   * (k, (Some(v), Some(w))) for v in `this`, or the pair (k, (None, Some(w))) if no elements
+   * in `this` have key k. Hash-partitions the resulting RDD using the existing partitioner/
+   * parallelism level.
+   */
+  def fullOuterJoin[W](other: RDD[(K, W)]): RDD[(K, (Option[V], Option[W]))] = {
+    fullOuterJoin(other, defaultPartitioner(self, other))
+  }
+
+  /**
+   * Perform a full outer join of `this` and `other`. For each element (k, v) in `this`, the
+   * resulting RDD will either contain all pairs (k, (Some(v), Some(w))) for w in `other`, or
+   * the pair (k, (Some(v), None)) if no elements in `other` have key k. Similarly, for each
+   * element (k, w) in `other`, the resulting RDD will either contain all pairs
+   * (k, (Some(v), Some(w))) for v in `this`, or the pair (k, (None, Some(w))) if no elements
+   * in `this` have key k. Hash-partitions the resulting RDD into the given number of partitions.
+   */
+  def fullOuterJoin[W](other: RDD[(K, W)], numPartitions: Int): RDD[(K, (Option[V], Option[W]))] = {
+    fullOuterJoin(other, new HashPartitioner(numPartitions))
+  }
+
   /**
    * Return the key-value pairs in this RDD to the master as a Map.
    *

core/src/test/scala/org/apache/spark/PartitioningSuite.scala

@@ -193,11 +193,13 @@ class PartitioningSuite extends FunSuite with SharedSparkContext with PrivateMet
     assert(grouped2.join(grouped4).partitioner === grouped4.partitioner)
     assert(grouped2.leftOuterJoin(grouped4).partitioner === grouped4.partitioner)
     assert(grouped2.rightOuterJoin(grouped4).partitioner === grouped4.partitioner)
+    assert(grouped2.fullOuterJoin(grouped4).partitioner === grouped4.partitioner)
     assert(grouped2.cogroup(grouped4).partitioner === grouped4.partitioner)
 
     assert(grouped2.join(reduced2).partitioner === grouped2.partitioner)
     assert(grouped2.leftOuterJoin(reduced2).partitioner === grouped2.partitioner)
     assert(grouped2.rightOuterJoin(reduced2).partitioner === grouped2.partitioner)
+    assert(grouped2.fullOuterJoin(reduced2).partitioner === grouped2.partitioner)
     assert(grouped2.cogroup(reduced2).partitioner === grouped2.partitioner)
 
     assert(grouped2.map(_ => 1).partitioner === None)
@@ -218,6 +220,7 @@ class PartitioningSuite extends FunSuite with SharedSparkContext with PrivateMet
     assert(intercept[SparkException]{ arrPairs.join(arrPairs) }.getMessage.contains("array"))
     assert(intercept[SparkException]{ arrPairs.leftOuterJoin(arrPairs) }.getMessage.contains("array"))
     assert(intercept[SparkException]{ arrPairs.rightOuterJoin(arrPairs) }.getMessage.contains("array"))
+    assert(intercept[SparkException]{ arrPairs.fullOuterJoin(arrPairs) }.getMessage.contains("array"))
     assert(intercept[SparkException]{ arrPairs.groupByKey() }.getMessage.contains("array"))
     assert(intercept[SparkException]{ arrPairs.countByKey() }.getMessage.contains("array"))
     assert(intercept[SparkException]{ arrPairs.countByKeyApprox(1) }.getMessage.contains("array"))

core/src/test/scala/org/apache/spark/rdd/PairRDDFunctionsSuite.scala

@@ -298,6 +298,21 @@ class PairRDDFunctionsSuite extends FunSuite with SharedSparkContext {
     ))
   }
 
+  test("fullOuterJoin") {
+    val rdd1 = sc.parallelize(Array((1, 1), (1, 2), (2, 1), (3, 1)))
+    val rdd2 = sc.parallelize(Array((1, 'x'), (2, 'y'), (2, 'z'), (4, 'w')))
+    val joined = rdd1.fullOuterJoin(rdd2).collect()
+    assert(joined.size === 6)
+    assert(joined.toSet === Set(
+      (1, (Some(1), Some('x'))),
+      (1, (Some(2), Some('x'))),
+      (2, (Some(1), Some('y'))),
+      (2, (Some(1), Some('z'))),
+      (3, (Some(1), None)),
+      (4, (None, Some('w')))
+    ))
+  }
+
   test("join with no matches") {
     val rdd1 = sc.parallelize(Array((1, 1), (1, 2), (2, 1), (3, 1)))
     val rdd2 = sc.parallelize(Array((4, 'x'), (5, 'y'), (5, 'z'), (6, 'w')))

core/src/test/scala/org/apache/spark/rdd/RDDSuite.scala

@@ -193,6 +193,7 @@ class RDDSuite extends FunSuite with SharedSparkContext {
     assert(rdd.join(emptyKv).collect().size === 0)
     assert(rdd.rightOuterJoin(emptyKv).collect().size === 0)
     assert(rdd.leftOuterJoin(emptyKv).collect().size === 2)
+    assert(rdd.fullOuterJoin(emptyKv).collect().size === 2)
     assert(rdd.cogroup(emptyKv).collect().size === 2)
     assert(rdd.union(emptyKv).collect().size === 2)
   }

docs/programming-guide.md

@@ -906,7 +906,7 @@ for details.
 <tr>
   <td> <b>join</b>(<i>otherDataset</i>, [<i>numTasks</i>]) </td>
   <td> When called on datasets of type (K, V) and (K, W), returns a dataset of (K, (V, W)) pairs with all pairs of elements for each key.
-    Outer joins are also supported through <code>leftOuterJoin</code> and <code>rightOuterJoin</code>.
+    Outer joins are supported through <code>leftOuterJoin</code>, <code>rightOuterJoin</code>, and <code>fullOuterJoin</code>.
   </td>
 </tr>
 <tr>

python/pyspark/join.py

@@ -80,6 +80,22 @@ def dispatch(seq):
     return _do_python_join(rdd, other, numPartitions, dispatch)
 
 
+def python_full_outer_join(rdd, other, numPartitions):
+    def dispatch(seq):
+        vbuf, wbuf = [], []
+        for (n, v) in seq:
+            if n == 1:
+                vbuf.append(v)
+            elif n == 2:
+                wbuf.append(v)
+        if not vbuf:
+            vbuf.append(None)
+        if not wbuf:
+            wbuf.append(None)
+        return [(v, w) for v in vbuf for w in wbuf]
+    return _do_python_join(rdd, other, numPartitions, dispatch)
+
+
 def python_cogroup(rdds, numPartitions):
     def make_mapper(i):
         return lambda (k, v): (k, (i, v))

python/pyspark/rdd.py

@@ -36,7 +36,7 @@
     BatchedSerializer, CloudPickleSerializer, PairDeserializer, \
     PickleSerializer, pack_long, AutoBatchedSerializer
 from pyspark.join import python_join, python_left_outer_join, \
-    python_right_outer_join, python_cogroup
+    python_right_outer_join, python_full_outer_join, python_cogroup
 from pyspark.statcounter import StatCounter
 from pyspark.rddsampler import RDDSampler, RDDStratifiedSampler
 from pyspark.storagelevel import StorageLevel
@@ -1375,7 +1375,7 @@ def leftOuterJoin(self, other, numPartitions=None):
 
         For each element (k, v) in C{self}, the resulting RDD will either
         contain all pairs (k, (v, w)) for w in C{other}, or the pair
-        (k, (v, None)) if no elements in other have key k.
+        (k, (v, None)) if no elements in C{other} have key k.
 
         Hash-partitions the resulting RDD into the given number of partitions.
 
@@ -1403,6 +1403,27 @@ def rightOuterJoin(self, other, numPartitions=None):
         """
         return python_right_outer_join(self, other, numPartitions)
 
+    def fullOuterJoin(self, other, numPartitions=None):
+        """
+        Perform a right outer join of C{self} and C{other}.
+
+        For each element (k, v) in C{self}, the resulting RDD will either
+        contain all pairs (k, (v, w)) for w in C{other}, or the pair
+        (k, (v, None)) if no elements in C{other} have key k.
+
+        Similarly, for each element (k, w) in C{other}, the resulting RDD will
+        either contain all pairs (k, (v, w)) for v in C{self}, or the pair
+        (k, (None, w)) if no elements in C{self} have key k.
+
+        Hash-partitions the resulting RDD into the given number of partitions.
+
+        >>> x = sc.parallelize([("a", 1), ("b", 4)])
+        >>> y = sc.parallelize([("a", 2), ("c", 8)])
+        >>> sorted(x.fullOuterJoin(y).collect())
+        [('a', (1, 2)), ('b', (4, None)), ('c', (None, 8))]
+        """
+        return python_full_outer_join(self, other, numPartitions)
+
     # TODO: add option to control map-side combining
     # portable_hash is used as default, because builtin hash of None is different
     # cross machines.

streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaPairDStream.scala

@@ -606,8 +606,9 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
   }
 
   /**
-   * Return a new DStream by applying 'join' between RDDs of `this` DStream and `other` DStream.
-   * The supplied org.apache.spark.Partitioner is used to control the partitioning of each RDD.
+   * Return a new DStream by applying 'left outer join' between RDDs of `this` DStream and
+   * `other` DStream. The supplied org.apache.spark.Partitioner is used to control
+   * the partitioning of each RDD.
    */
   def leftOuterJoin[W](
       other: JavaPairDStream[K, W],
@@ -624,8 +625,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
    * number of partitions.
    */
   def rightOuterJoin[W](other: JavaPairDStream[K, W]): JavaPairDStream[K, (Optional[V], W)] = {
-    implicit val cm: ClassTag[W] =
-      implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[W]]
+    implicit val cm: ClassTag[W] = fakeClassTag
     val joinResult = dstream.rightOuterJoin(other.dstream)
     joinResult.mapValues{case (v, w) => (JavaUtils.optionToOptional(v), w)}
   }
@@ -658,6 +658,52 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
     joinResult.mapValues{case (v, w) => (JavaUtils.optionToOptional(v), w)}
   }
 
+  /**
+   * Return a new DStream by applying 'full outer join' between RDDs of `this` DStream and
+   * `other` DStream. Hash partitioning is used to generate the RDDs with Spark's default
+   * number of partitions.
+   */
+  def fullOuterJoin[W](other: JavaPairDStream[K, W])
+      : JavaPairDStream[K, (Optional[V], Optional[W])] = {
+    implicit val cm: ClassTag[W] = fakeClassTag
+    val joinResult = dstream.fullOuterJoin(other.dstream)
+    joinResult.mapValues{ case (v, w) =>
+      (JavaUtils.optionToOptional(v), JavaUtils.optionToOptional(w))
+    }
+  }
+
+  /**
+   * Return a new DStream by applying 'full outer join' between RDDs of `this` DStream and
+   * `other` DStream. Hash partitioning is used to generate the RDDs with `numPartitions`
+   * partitions.
+   */
+  def fullOuterJoin[W](
+      other: JavaPairDStream[K, W],
+      numPartitions: Int
+    ): JavaPairDStream[K, (Optional[V], Optional[W])] = {
+    implicit val cm: ClassTag[W] = fakeClassTag
+    val joinResult = dstream.fullOuterJoin(other.dstream, numPartitions)
+    joinResult.mapValues{ case (v, w) =>
+      (JavaUtils.optionToOptional(v), JavaUtils.optionToOptional(w))
+    }
+  }
+
+  /**
+   * Return a new DStream by applying 'full outer join' between RDDs of `this` DStream and
+   * `other` DStream. The supplied org.apache.spark.Partitioner is used to control
+   * the partitioning of each RDD.
+   */
+  def fullOuterJoin[W](
+      other: JavaPairDStream[K, W],
+      partitioner: Partitioner
+    ): JavaPairDStream[K, (Optional[V], Optional[W])] = {
+    implicit val cm: ClassTag[W] = fakeClassTag
+    val joinResult = dstream.fullOuterJoin(other.dstream, partitioner)
+    joinResult.mapValues{ case (v, w) =>
+      (JavaUtils.optionToOptional(v), JavaUtils.optionToOptional(w))
+    }
+  }
+
   /**
    * Save each RDD in `this` DStream as a Hadoop file. The file name at each batch interval is
    * generated based on `prefix` and `suffix`: "prefix-TIME_IN_MS.suffix".

streaming/src/main/scala/org/apache/spark/streaming/dstream/PairDStreamFunctions.scala

@@ -568,6 +568,42 @@ class PairDStreamFunctions[K, V](self: DStream[(K,V)])
     )
   }
 
+  /**
+   * Return a new DStream by applying 'full outer join' between RDDs of `this` DStream and
+   * `other` DStream. Hash partitioning is used to generate the RDDs with Spark's default
+   * number of partitions.
+   */
+  def fullOuterJoin[W: ClassTag](other: DStream[(K, W)]): DStream[(K, (Option[V], Option[W]))] = {
+    fullOuterJoin[W](other, defaultPartitioner())
+  }
+
+  /**
+   * Return a new DStream by applying 'full outer join' between RDDs of `this` DStream and
+   * `other` DStream. Hash partitioning is used to generate the RDDs with `numPartitions`
+   * partitions.
+   */
+  def fullOuterJoin[W: ClassTag](
+      other: DStream[(K, W)],
+      numPartitions: Int
+    ): DStream[(K, (Option[V], Option[W]))] = {
+    fullOuterJoin[W](other, defaultPartitioner(numPartitions))
+  }
+
+  /**
+   * Return a new DStream by applying 'full outer join' between RDDs of `this` DStream and
+   * `other` DStream. The supplied org.apache.spark.Partitioner is used to control
+   * the partitioning of each RDD.
+   */
+  def fullOuterJoin[W: ClassTag](
+      other: DStream[(K, W)],
+      partitioner: Partitioner
+    ): DStream[(K, (Option[V], Option[W]))] = {
+    self.transformWith(
+      other,
+      (rdd1: RDD[(K, V)], rdd2: RDD[(K, W)]) => rdd1.fullOuterJoin(rdd2, partitioner)
+    )
+  }
+
   /**
    * Save each RDD in `this` DStream as a Hadoop file. The file name at each batch interval
    * is generated based on `prefix` and `suffix`: "prefix-TIME_IN_MS.suffix"

streaming/src/test/scala/org/apache/spark/streaming/BasicOperationsSuite.scala

@@ -303,6 +303,21 @@ class BasicOperationsSuite extends TestSuiteBase {
     testOperation(inputData1, inputData2, operation, outputData, true)
   }
 
+  test("fullOuterJoin") {
+    val inputData1 = Seq( Seq("a", "b"), Seq("a", ""), Seq(""), Seq() )
+    val inputData2 = Seq( Seq("a", "b"), Seq("b", ""), Seq(), Seq("")   )
+    val outputData = Seq(
+      Seq( ("a", (Some(1), Some("x"))), ("b", (Some(1), Some("x"))) ),
+      Seq( ("", (Some(1), Some("x"))), ("a", (Some(1), None)), ("b", (None, Some("x"))) ),
+      Seq( ("", (Some(1), None)) ),
+      Seq( ("", (None, Some("x"))) )
+    )
+    val operation = (s1: DStream[String], s2: DStream[String]) => {
+      s1.map(x => (x, 1)).fullOuterJoin(s2.map(x => (x, "x")))
+    }
+    testOperation(inputData1, inputData2, operation, outputData, true)
+  }
+
   test("updateStateByKey") {
     val inputData =
       Seq(