org.apache.datasketches:datasketches-java:1.2.0-incubatingto perform distinct counting as well as evaluating set operations.
DistinctCountThetaSketch(<thetaSketchColumn>, <thetaSketchParams>, predicate1, predicate2..., postAggregationExpressionToEvaluate) -> Long
thetaSketchColumn(required): Name of the column to aggregate on.
thetaSketchParams(required): Parameters for constructing the intermediate theta-sketches.
nominalEntries(defaults to 4096).
predicates(optional)_: _ These are individual predicates of form
lhs <op> rhswhich are applied on rows selected by the
whereclause. During intermediate sketch aggregation, sketches from the
thetaSketchColumnthat satisfies these predicates are unionized individually. For example, all filtered rows that match
country=USAare unionized into a single sketch. Complex predicates that are created by combining (AND/OR) of individual predicates is supported.
postAggregationExpressionToEvaluate(required): The set operation to perform on the individual intermediate sketches for each of the predicates. Currently supported operations are
SET_DIFF, SET_UNION, SET_INTERSECT, where DIFF requires two arguments and the UNION/INTERSECT allow more than two arguments.
1986is the only one in common)