org.apache.spark.sql.catalyst.expressions.aggregate.DeclarativeAggregate
Represents this attribute at the mutable buffer side.
Represents this attribute at the input buffer side (the data value is read-only).
A helper class for representing an attribute used in merging two aggregation buffers. When merging two buffers,
bufferLeftandbufferRight, we merge buffer values and then update bufferLeft. A RichAttribute of an AttributeReferenceahas two functionsleftandright, which representainbufferLeftandbufferRight, respectively.