Re: Reading from a centralized stored

2015-01-06 Thread Cody Koeninger
No, most rdds partition input data appropriately. On Tue, Jan 6, 2015 at 1:41 PM, Franc Carter franc.car...@rozettatech.com wrote: One more question, to be clarify. Will every node pull in all the data ? thanks On Tue, Jan 6, 2015 at 12:56 PM, Cody Koeninger c...@koeninger.org wrote: If

Re: Reading from a centralized stored

2015-01-06 Thread Franc Carter
Ah, so it's rdd specific - that would make sense. For those systems where it is possible to extract sensible susbets the rdds do so. My use case, which is probably biasing my thinking is DynamoDb which I don't think can efficiently extract records from M-to-N cheers On Wed, Jan 7, 2015 at 6:59

Re: Reading from a centralized stored

2015-01-05 Thread Cody Koeninger
If you are not co-locating spark executor processes on the same machines where the data is stored, and using an rdd that knows about which node to prefer scheduling a task on, yes, the data will be pulled over the network. Of the options you listed, S3 and DynamoDB cannot have spark running on

Re: Reading from a centralized stored

2015-01-05 Thread Franc Carter
Thanks, that's what I suspected. cheers On Tue, Jan 6, 2015 at 12:56 PM, Cody Koeninger c...@koeninger.org wrote: If you are not co-locating spark executor processes on the same machines where the data is stored, and using an rdd that knows about which node to prefer scheduling a task on,

Reading from a centralized stored

2015-01-05 Thread Franc Carter
Hi, I'm trying to understand how a Spark Cluster behaves when the data it is processing resides on a centralized/remote store (S3, Cassandra, DynamoDB, RDBMS etc). Does every node in the cluster retrieve all the data from the central store ? thanks -- *Franc Carter* | Systems Architect |