Practicing caching: the SQL
Previously, we examined two DataFrames: df1 and df2 (which is created from df1). We tried caching df1, but not df2. In this exercise, we'll examine the effects of caching df2, but not df1.
Once again, note the amount of time that each action takes. We'll be comparing these in the next exercise. Which tasks are sped up? Which are slowed down?
Diese Übung ist Teil des Kurses
Introduction to Spark SQL in Python
Anleitung zur Übung
- Cache
df2, but notdf1. - Run a first action on
df1and repeat it, then run an actiondf2and repeat it. This has been done for you.
Interaktive Übung
Vervollständige den Beispielcode, um diese Übung erfolgreich abzuschließen.
# Unpersist df1 and df2 and initializes a timer
prep(df1, df2)
# Persist df2 using memory and disk storage level
df2.persist(____)
# Run actions both dataframes
run(df1, "df1_1st")
run(df1, "df1_2nd")
run(df2, "df2_1st")
run(df2, "df2_2nd", elapsed=True)