Hey,
I'm seeing extreme slowness in withColumn when it's used in a loop. I'm
running this code:
for (int i = 0; i < NUM_ITERATIONS ++i) {
    df = df.withColumn("col"+i, new Column(new Literal(i,
DataTypes.IntegerType)));
}
where df is initially a trivial dataframe. Here are the results of running
with different values of NUM_ITERATIONS:
iterations time
25 3s
50 11s
75 31s
100 76s
125 159s
150 283s
When I update the DataFrame by manually copying/appending to the column
array and using DataFrame.select, it runs in about half the time, but this
is still untenable at any significant number of iterations.
Any insight?
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