Until now, an user aggregation was used for viewers metric computation. But with
elasticsearch datasource type, the count reducer function is limited to 500
inputs. Nevertheless, lots of videos count more than 500 users.
Proposal
To overcome this bug from elasticsearch, the cardinality metric is applied on viewed
statements and the aggregation is made on context.contextActivities.parent.id
(i.e. course session ID).
Purpose
Until now, an user aggregation was used for viewers metric computation. But with elasticsearch datasource type, the count reducer function is limited to 500 inputs. Nevertheless, lots of videos count more than 500 users.
Proposal
To overcome this bug from elasticsearch, the cardinality metric is applied on viewed statements and the aggregation is made on
context.contextActivities.parent.id(i.e. course session ID).