OPAL Filter Verbs

Filter verbs select particular rows from the input row set, emitting the matches as output.

Verb

Description

always

When the verb input is a Resource dataset, always selects all resources that match the predicate at all times.

bottomk

Selects all data for each of the bottom k ranked groups.

ever

When the verb input is a Resource dataset, ever selects all resources that at some point matched the predicate.

filter

Exclude rows from the input dataset that do not match the given predicate expression.

limit

Select the first count rows based on the current ordering of the input and filter out the rest.

never

When the verb input is a Resource dataset, never selects all resources that at no point matched the predicate.

topk

Selects all data for each of top k ranked groups.