schema

Returns DataFrameSchema object with DataFrame schema description. It can be printed to see column structure.

ColumnGroups are marked by indentation:

df.schema()

Output:

name:
    firstName: String
    lastName: String
age: Int
city: String?
weight: Int?
isHappy: Boolean

FrameColumns are marked with *:

df.groupBy { city }.schema()

Output:

city: String?
group: *
    name:
        firstName: String
        lastName: String
    age: Int
    city: String?
    weight: Int?
    isHappy: Boolean

24 October 2025