rollup()

Since 1.16.0

Combine multiple aggregates created with freq_agg or mcv_agg functions. This function requires that the source aggregates have been created with the same parameters (same min_freq for freq_agg, same n-factor and skew, if used, for a mcv_agg).

This produces a very similar aggregate to running the same aggregate function over all the source data. In most cases, any difference is no more than what you might get from simply reordering the input. However, if the source data for the different aggregates is very differently distributed, the rollup result may have looser frequency bounds.

Arguments

The syntax is:

rollup(
    agg SpaceSavingAggregate
) RETURNS SpaceSavingAggregate

Name	Type	Default	Required	Description
agg	SpaceSavingAggregate	-	✔	The aggregates to roll up. These must have been created with the same parameters.

Returns

Column	Type	Description
rollup	SpaceSavingAggregate	An aggregate containing the most common elements from all of the underlying data for all of the aggregates.