ClickHouse does this using arrays. There's a rich set of functions to pull grouped values into arrays, process them with lambdas (e.g, map, sort, etc.), and exp

ClickHouse does this using arrays. There's a rich set of functions to pull grouped values into arrays, process them with lambdas (e.g, map, sort, etc.), and explode them back out into tabular result. Here's a slide deck with examples from a recent presentation: https://altinity.com/presentations/introduction-to-high-velocity-analytics-using-clickhouse-arrays-2 https://altinity.com/presentations/introduction-to-high-velo... ClickHouse sneaks a functional programming model with lambda expressions into SQL. It's not standard SQL but has enormous flexibility.