Re: What's the meaning when the partitions is zero?
When numPartitions is 0, there is no data in the rdd: so getPartition is never invoked. - Mridul On Friday, September 16, 2016, WangJianfei wrote: > if so, we will get exception when the numPartitions is 0. > def getPartition(key: Any): Int = key match { > case null => 0 > //case None => 0 > case _ => Utils.nonNegativeMod(key.hashCode, numPartitions) > } > > > > -- > View this message in context: http://apache-spark- > developers-list.1001551.n3.nabble.com/What-s-the-meaning- > when-the-partitions-is-zero-tp18957p18967.html > Sent from the Apache Spark Developers List mailing list archive at > Nabble.com. > > - > To unsubscribe e-mail: dev-unsubscr...@spark.apache.org > >
Re: What's the meaning when the partitions is zero?
if so, we will get exception when the numPartitions is 0. def getPartition(key: Any): Int = key match { case null => 0 //case None => 0 case _ => Utils.nonNegativeMod(key.hashCode, numPartitions) } -- View this message in context: http://apache-spark-developers-list.1001551.n3.nabble.com/What-s-the-meaning-when-the-partitions-is-zero-tp18957p18967.html Sent from the Apache Spark Developers List mailing list archive at Nabble.com. - To unsubscribe e-mail: dev-unsubscr...@spark.apache.org
Re: What's the meaning when the partitions is zero?
They are valid, especially in partition pruning. On Friday, September 16, 2016, Sean Owen wrote: > There are almost no cases in which you'd want a zero-partition RDD. > The only one I can think of is an empty RDD, where the number of > partitions is irrelevant. Still, I would not be surprised if other > parts of the code assume at least 1 partition. > > Maybe this check could be tightened. It would be interesting to see if > the tests catch any scenario where a 0-partition RDD is created, and > why. > > On Fri, Sep 16, 2016 at 7:54 AM, WangJianfei > > wrote: > > class HashPartitioner(partitions: Int) extends Partitioner { > > require(partitions >= 0, s"Number of partitions ($partitions) cannot be > > negative.") > > > > the soruce code require(partitions >=0) ,but I don't know why it makes > sense > > when the partitions is 0. > > > > > > > > -- > > View this message in context: http://apache-spark- > developers-list.1001551.n3.nabble.com/What-s-the-meaning- > when-the-partitions-is-zero-tp18957.html > > Sent from the Apache Spark Developers List mailing list archive at > Nabble.com. > > > > - > > To unsubscribe e-mail: dev-unsubscr...@spark.apache.org > > > > - > To unsubscribe e-mail: dev-unsubscr...@spark.apache.org > >
Re: What's the meaning when the partitions is zero?
There are almost no cases in which you'd want a zero-partition RDD. The only one I can think of is an empty RDD, where the number of partitions is irrelevant. Still, I would not be surprised if other parts of the code assume at least 1 partition. Maybe this check could be tightened. It would be interesting to see if the tests catch any scenario where a 0-partition RDD is created, and why. On Fri, Sep 16, 2016 at 7:54 AM, WangJianfei wrote: > class HashPartitioner(partitions: Int) extends Partitioner { > require(partitions >= 0, s"Number of partitions ($partitions) cannot be > negative.") > > the soruce code require(partitions >=0) ,but I don't know why it makes sense > when the partitions is 0. > > > > -- > View this message in context: > http://apache-spark-developers-list.1001551.n3.nabble.com/What-s-the-meaning-when-the-partitions-is-zero-tp18957.html > Sent from the Apache Spark Developers List mailing list archive at Nabble.com. > > - > To unsubscribe e-mail: dev-unsubscr...@spark.apache.org > - To unsubscribe e-mail: dev-unsubscr...@spark.apache.org
What's the meaning when the partitions is zero?
class HashPartitioner(partitions: Int) extends Partitioner { require(partitions >= 0, s"Number of partitions ($partitions) cannot be negative.") the soruce code require(partitions >=0) ,but I don't know why it makes sense when the partitions is 0. -- View this message in context: http://apache-spark-developers-list.1001551.n3.nabble.com/What-s-the-meaning-when-the-partitions-is-zero-tp18957.html Sent from the Apache Spark Developers List mailing list archive at Nabble.com. - To unsubscribe e-mail: dev-unsubscr...@spark.apache.org