persist persists the SparkDataFrame with the specified storage level.
Note: Read the programming guide <http://spark.apache.org/docs/latest/programming-guide.html#rdd-persistence>__ to find out more about the different storage levels and how to choose between them.
- persist(SparkDataFrame, “storageLevel”)
- SparkDataFrame: Any SparkDataFrame
- storageLevel: String, storage level to persist SparkDataFrame at. For eg: “MEMORY_ONLY”, “MEMORY_AND_DISK”, “DISK_ONLY”, etc.
require(SparkR) # Create SparkR DataFrame using the faithful dataset from R df <- createDataFrame(faithful) # Displays the content of the SparkDataFrame to stdout head(df)
# Cache df in memory only (this is thet same result as using cache()) persist(df, "MEMORY_ONLY")
To see how much of your data was cached, perform a SparkDataFrame Action and refer to Spark UI > Storage.
# Perform SparkDataFrame operations on cached df collect(df)