Work with nested row values

This how-to shows how to create and inspect nested scalar values without changing relation cardinality.

Use nested scalar helpers when each input row should remain one output row. Use generator helpers such as explode(...) only when an array or struct should reshape the relation.

Add array-derived columns

Build arrays with array(...), then inspect them with row-level helpers such as cardinality(...), array_contains(...), and element_at(...).

from pub::incql.functions import array, array_contains, cardinality, col, element_at, lit

projected = (
    events
        .with_column("tags", array([lit("paid"), col("source")]))
        .with_column("tag_count", cardinality(col("tags")))
        .with_column("has_paid_tag", array_contains(col("tags"), "paid"))
        .with_column("first_tag", element_at(col("tags"), 1))
)

element_at(...), array_position(...), and array_slice(...) use one-based array positions. For exact helper contracts, see Nested data functions.