drill-down

grouping →
drill-down(
    ...expressions: expression
) → grouping

Refines each existing group by appending dimensions derived from its values.

Parameters

Name	Type	Required	Description
expressions	expression	Variadic (one or more)	One or more expressions whose results are appended to the existing key.

Argument evaluation

Visits each value within each group of the grouping supplied as pipeline input to this drill-down call, in parent-group and value order.

• expressions: Each supplied expression is evaluated once per grouped value, in declaration order, with that value as its context; .field reads that value’s field.

Behavior

Appends to an existing tuple key or starts a tuple with an existing scalar key. Derived tuples remain single dimensions. Structural equality includes null; parent groups, first-seen subgroups and values retain their order. Empty groups produce no subgroups. Like group-by, requires one or more positional expressions; named arguments and spread are rejected.

Break country sales into annual revenue

The first example starts with orders grouped by country. drill-down(.year) splits each country group using the year on each order: Belgium becomes separate 2025 and 2026 groups, while France keeps its own 2025 group. summarize then adds the order amounts within each new group; the resulting keys are (country, year).

Add year and sales channel together

The second example starts with existing country groups and appends two dimensions in one call. Both .year and .channel read each order inside its current country group, producing (country, year, channel) keys. The country is retained from the existing key; it does not need to appear on the grouped orders.

Examples

{
  {country := "BE", year := 2025, amount := 120},
  {country := "FR", year := 2025, amount := 90},
  {country := "BE", year := 2026, amount := 80},
  {country := "BE", year := 2025, amount := 30}
}
| group-by(.country)
| drill-down(.year)
| summarize(map(.amount) | sum)
→ !{
  (T("BE", 2025) => 150),
  (T("BE", 2026) => 80),
  (T("FR", 2025) => 90)
}

#{
  ("BE" => {
    {year := 2025, channel := "web", amount := 120},
    {year := 2025, channel := "store", amount := 30},
    {year := 2026, channel := "web", amount := 80}
  }),
  ("FR" => {
    {year := 2025, channel := "web", amount := 90}
  })
}
| drill-down(.year, .channel)
| summarize(map(.amount) | sum)
→ !{
  (T("BE", 2025, "web") => 120),
  (T("BE", 2025, "store") => 30),
  (T("BE", 2026, "web") => 80),
  (T("FR", 2025, "web") => 90)
}

Kind: Function
Scope: grouping
Aliases: None