Usage

view: view_name {  measure: field_name {    approximate:yes  }}

Definition

See theDialect support forapproximate section on this page for the list of dialects that supportindexes.

Theapproximate parameter lets you use approximate counting with measures oftype: count andtype: count_distinct. With large datasets, approximate counts can bemuch faster than exact counts and are typically within a few percent of the actual value. Please check your SQL dialect's documentation to understand the speed and accuracy tradeoffs of this method.

measure: apx_unique_count {  type: count_distinct  approximate: yes   # default value is no  sql: ${id} ;;}

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Turning onapproximate with a measure oftype: count might seem unnecessary, because the approximate counting feature applies only to distinct counts. However, there are some situations when Looker automatically turns measures oftype: count into a distinct count of a primary key to provide accurate results for joined views. In those situations, approximate counting may be useful.

Dialect support forapproximate

The ability to useapproximate depends on the database dialect your Looker connection is using. In the latest version of Looker, the following dialects supportapproximate: