Re: Order groups by their keys

2015-07-19 Thread hagersaleh
why not found Although use library .sortPartition(1, Order.ASCENDING) -- View this message in context: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Order-groups-by-their-keys-tp2056p2153.html Sent from the Apache Flink User Mailing List archive. mailing list archive at

Re: Order groups by their keys

2015-07-15 Thread Fabian Hueske
Yes, going to parallelism 1 is another option but you don't have to use a fake-reduce to enforce sorting. You can simply do: DataSet> result = ... result .sortPartition(1, Order.ASCENDING).setParallelism(1) // sort on first String field .output(...); Fabian 2015-07-15 15:32 GMT+02:00 Matthia

Re: Order groups by their keys

2015-07-15 Thread Matthias J. Sax
Hi Robert, global sorting of the final output is currently no supported by Flink out-of-the-box. The reason is, that a global sort requires all data to be processed by a single node (what contradicts data parallelism). For small output, you could use a final "reduce" with no key (ie, all data go

Re: Order groups by their keys

2015-07-15 Thread Fabian Hueske
Hi Robert, there are two issues involved here. 1) Flink does not support totally ordered paralllel output out-of-the box. Fully sorting data in parallel requires range partitioning which requires some knowledge of the data (distribution of the key values) to produce balanced partitions. Flink doe