CollectSet Expression¶

CollectSet is a Collect expression (with a mutable.HashSet[Any]] aggregation buffer).

Creating Instance¶

CollectSet takes the following to be created:

• Child Expression
• mutableAggBufferOffset (default: 0)
• inputAggBufferOffset (default: 0)

CollectSet is created when:

• Catalyst DSL's collectSet is used
• collect_set standard function is used
• collect_set SQL function is used

Pretty Name¶

prettyName: String

prettyName is part of the Expression abstraction.

prettyName is collect_set.

Creating Aggregation Buffer¶

createAggregationBuffer(): mutable.HashSet[Any]

createAggregationBuffer is part of the TypedImperativeAggregate abstraction.

createAggregationBuffer creates an empty mutable.HashSet (Scala).

Interpreted Execution¶

eval(
  buffer: mutable.HashSet[Any]): Any

eval is part of the TypedImperativeAggregate abstraction.

eval creates a GenericArrayData with an array based on the DataType of the child expression:

• For BinaryType, eval...FIXME
• Otherwise, eval...FIXME

EliminateDistinct Logical Optimization¶

CollectSet is isDuplicateAgnostic per EliminateDistinct logical optimization.