Optimization of application of index based group by

Situation
Under very restrictive preconditions Exasol uses existing indices to reduce TEMP usage of large aggregations and hence, improve performance of such queries.

It has turned out that especially for cases of few group keys or strong root filters, the standard group by was faster than the index based variant.

Improvement
The use of index based group by has been restricted to cases of many index keys, weak root filters and/or the existence of a having clause.