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| <h2 title="Class Partitioner" class="title">Class Partitioner</h2> |
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| <pre>public abstract class <span class="typeNameLabel">Partitioner</span> |
| extends Object |
| implements scala.Serializable</pre> |
| <div class="block">An object that defines how the elements in a key-value pair RDD are partitioned by key. |
| Maps each key to a partition ID, from 0 to <code>numPartitions - 1</code>. |
| <p> |
| Note that, partitioner must be deterministic, i.e. it must return the same partition id given |
| the same partition key.</div> |
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| <td class="colFirst"><code>static <a href="../../../org/apache/spark/Partitioner.html" title="class in org.apache.spark">Partitioner</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../org/apache/spark/Partitioner.html#defaultPartitioner-org.apache.spark.rdd.RDD-scala.collection.Seq-">defaultPartitioner</a></span>(<a href="../../../org/apache/spark/rdd/RDD.html" title="class in org.apache.spark.rdd">RDD</a><?> rdd, |
| scala.collection.Seq<<a href="../../../org/apache/spark/rdd/RDD.html" title="class in org.apache.spark.rdd">RDD</a><?>> others)</code> |
| <div class="block">Choose a partitioner to use for a cogroup-like operation between a number of RDDs.</div> |
| </td> |
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| <td class="colFirst"><code>abstract int</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../org/apache/spark/Partitioner.html#getPartition-java.lang.Object-">getPartition</a></span>(Object key)</code> </td> |
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| <td class="colFirst"><code>abstract int</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../org/apache/spark/Partitioner.html#numPartitions--">numPartitions</a></span>()</code> </td> |
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| <h4>Partitioner</h4> |
| <pre>public Partitioner()</pre> |
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| <h4>defaultPartitioner</h4> |
| <pre>public static <a href="../../../org/apache/spark/Partitioner.html" title="class in org.apache.spark">Partitioner</a> defaultPartitioner(<a href="../../../org/apache/spark/rdd/RDD.html" title="class in org.apache.spark.rdd">RDD</a><?> rdd, |
| scala.collection.Seq<<a href="../../../org/apache/spark/rdd/RDD.html" title="class in org.apache.spark.rdd">RDD</a><?>> others)</pre> |
| <div class="block">Choose a partitioner to use for a cogroup-like operation between a number of RDDs. |
| <p> |
| If spark.default.parallelism is set, we'll use the value of SparkContext defaultParallelism |
| as the default partitions number, otherwise we'll use the max number of upstream partitions. |
| <p> |
| When available, we choose the partitioner from rdds with maximum number of partitions. If this |
| partitioner is eligible (number of partitions within an order of maximum number of partitions |
| in rdds), or has partition number higher than or equal to default partitions number - we use |
| this partitioner. |
| <p> |
| Otherwise, we'll use a new HashPartitioner with the default partitions number. |
| <p> |
| Unless spark.default.parallelism is set, the number of partitions will be the same as the |
| number of partitions in the largest upstream RDD, as this should be least likely to cause |
| out-of-memory errors. |
| <p> |
| We use two method parameters (rdd, others) to enforce callers passing at least 1 RDD.</div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>rdd</code> - (undocumented)</dd> |
| <dd><code>others</code> - (undocumented)</dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>(undocumented)</dd> |
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| <pre>public abstract int numPartitions()</pre> |
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| <pre>public abstract int getPartition(Object key)</pre> |
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