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twinsevil avatar image
twinsevil asked ·

Is there joinWithCassandraTable() in open-source pyspark?

Hello!

Is there a joinWithCassandraTable() method in the free open source version for pyspark?

Or is it implemented only in the DSE version?

spark-cassandra-connector
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jaroslaw.grabowski_50515 avatar image
jaroslaw.grabowski_50515 answered ·

Hi! SCC 2.5.x and newer has Direct Join support (joinWithCassandraTable but for dataframes). I don't have python samples but here is a good scala article about Direct Join http://www.russellspitzer.com/2018/05/23/DSEDirectJoin/.

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twinsevil avatar image twinsevil ·

Are you sure this feature is implemented in the open source version of the connector for pyspark?

I am using spark-cassandra-connector_2.12 and Spark 3.0.1 but I can't find the directJoin method.

A simple join of two dataframes (one very small, the other very large) results to full table scan.

What am I doing wrong?

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twinsevil avatar image twinsevil ·

Thanks for the help, I figured out what the problem was.

In order for the direct join to work, it was necessary to set the following settings when creating the Spark Context:


spark = SparkSession.builder.\
     config('directJoinSetting', 'on').\
     config("spark.sql.extensions",  "com.datastax.spark.connector.CassandraSparkExtensions").\
     appName('directJoin').getOrCreate() 
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