Improve performance of aggregate expressions by implementing group accumulators #1627
Description
What is the problem the feature request solves?
DataFusion has a fast path for aggregates that implement group accumulators.
See #1275 (comment) for one example where we saw a 4x speedup.
We should apply this change to the following Comet aggregates.
- stddev
- correlation
- covariance
- variance
Describe the potential solution
No response
Additional context
No response