approx_count_distinct(expr[, relativeSD]) – Returns the estimated cardinality by HyperLogLog++. `relativeSD` defines the maximum estimation error allowed.
Platforms: WhereOS, Spark, Hive
More functions can be added to WhereOS via Python or R bindings or as Java & Scala UDF (user-defined function), UDAF (user-defined aggregation function) and UDTF (user-defined table generating function) extensions. Custom libraries can be added on via Settings-page or installed from WhereOS Store.