Should we keep aggregators

[John W Vines <jo...@ugov.gov>]

In 1.4 we have added Combiners, which are extensions to Iterators which provide Aggregator functionality. We care because this, along with our changes to Filter, make all of our internal elements operate in the same type of code. (For the record, Aggregators used to be applied in an AggregatingIterator.)  Now that we have this functionality, we need to decide on what to do with Aggregators. They are the only option in 1.3, so there is some user base utilizing them. We did not deprecate them in 1.4, but that is an option. If not there, we need to decide when/if to deprecate them at all (and then whether or not we want to give it an extension to it's life-cycle while deprecated). The sooner we deprecate, the less likely users will cement themselves into using them rather than Combiners. This also means less code to maintain. However, there is the possibility that there are unknown (at least to me) benefits to using Aggregators over Combiners. I think we need to make a decision on this before we can proceed with the release of 1.4 since this will drive whether we end up deprecating more (Aggregators) or undeprecating things (PerColumnIteratorConfig).

Thoughts?

John