follow#

Type of operation: Join

Description#

Return the rows from the additional joined dataset that have a match anywhere in the query time window.

follow performs a nontemporal semijoin. The join will select any rows from the first dataset that have at least one matching row in the second dataset.

Usage#

follow [ frame ], predicate_1, predicate_2, ...

Argument

Type

Optional

Repeatable

Restrictions

frame

frame

yes

no

constant

predicate

bool

no

yes

none

Accelerable#

follow is accelerable if there is a frame() argument. A dataset that only uses accelerable verbs can be accelerated, making queries on the dataset respond faster.

Examples#

Semijoin the default dataset with the ‘right’ dataset, returning rows from ‘right’ where there exists a key match at any point in time within the query window.

follow frame(back:30m), [email protected]_id

Semijoin the default dataset with the ‘right’ dataset, returning rows from ‘right’ where there exists a key match within 30 minutes in time.

follow [email protected]_id and sensor_value>@right.sensor_value

Semijoin the default dataset with the ‘right’ dataset, returning rows from ‘right’ whose sensor_value is less than the value from the default dataset for the same sensor_id at any point in time within the query window.