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From dueckm <matthias.du...@fiduciagad.de>
Subject Are join/groupBy operations with wide Java Beans using Dataset API much slower than using RDD API?
Date Thu, 04 Aug 2016 11:27:43 GMT
Hello,

I built a prototype that uses join and groupBy operations via Spark RDD API.
Recently I migrated it to the Dataset API. Now it runs much slower than with
the original RDD implementation. 
Did I do something wrong here? Or is this a price I have to pay for the more
convienient API?
Is there a known solution to deal with this effect (eg configuration via
"spark.sql.shuffle.partitions" - but now could I determine the correct
value)?
In my prototype I use Java Beans with a lot of attributes. Does this slow
down Spark-operations with Datasets?

Here I have an simple example, that shows the difference: 
JoinGroupByTest.zip
<http://apache-spark-user-list.1001560.n3.nabble.com/file/n27473/JoinGroupByTest.zip>
 
- I build 2 RDDs and join and group them. Afterwards I count and display the
joined RDDs.  (Method de.testrddds.JoinGroupByTest.joinAndGroupViaRDD() )
- When I do the same actions with Datasets it takes approximately 40 times
as long (Methodd e.testrddds.JoinGroupByTest.joinAndGroupViaDatasets()).

Thank you very much for your help.
Matthias

PS1: excuse me for sending this post more than once, but I am new to this
mailing list and probably did something wrong when registering/subscribing,
so my previous postings have not been accepted ...

PS2: See the appended screenshots taken from Spark UI (jobs 0/1 belong to
RDD implementation, jobs 2/3 to Dataset):
<http://apache-spark-user-list.1001560.n3.nabble.com/file/n27473/jobs.png> 
<http://apache-spark-user-list.1001560.n3.nabble.com/file/n27473/Job_RDD_Details.png>

<http://apache-spark-user-list.1001560.n3.nabble.com/file/n27473/Job_Dataset_Details.png>




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