# topk¶

Type of operation: Filter

## Description¶

Selects all data for each of top k ranked groups. If no rank method is provided, a default one will be used. If no grouping is specified, the set of primary key columns will be used as the grouping.

## Usage¶

topk k [ , rank ] [ , groupby ]


Argument

Type

Required

Multiple

k

int64

Required

Only one

rank

expression

Optional

Only one

groupby

fieldref

Optional

Only one

## Accelerable¶

topk is never accelerable. A dataset that only uses accelerable verbs can be accelerated, making queries on the dataset respond faster.

## Examples¶

topk 100


Select the top 100 groups using the default rank method: the hash of the group identifiers (the set of primary key columns).

topk 100, group_by(clusterUid, namespace)


Similar to the first example, but explicitly specifying the grouping

topk 100, max(restartCount)


Similar to the first example, but using a custom rank method to find the groups with most restarts

topk 1, group_by()


This topk operates on empty grouping, where all rows belong to the same group, and hence all rows will be selected