Returns the count of distinct row values in a group.
DISTINCTCOUNTHLL()is faster than DISTINCTCOUNT()if data is pre-aggregated at ingestion or aggregated at a server with enough records. This performance improvement increases when comparing large datasets.
If very few records are pre-aggregated, DISTINCTCOUNT()is faster than DISTINCTCOUNTHLL()because the serialized HLL size is larger than sending individual values.
Signature
DISTINCTCOUNT(colName)
Usage Examples
These examples are based on the .
select DISTINCTCOUNT(league) AS value
from baseballStats
value
7
select DISTINCTCOUNT(teamID) AS value
from baseballStats
