approx_count_distinct [WhereOS, SQL, Spark, Hive]

Class org.apache.spark.sql.catalyst.expressions.aggregate.HyperLogLogPlusPlus
Usage approx_count_distinct(expr[, relativeSD]) - Returns the estimated cardinality by HyperLogLog++. `relativeSD` defines the maximum estimation error allowed.

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.

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