This also involved some other test changes:
- Added a factory.mergeRunners step to AggregationTestHelper's groupBy chain, since the v2
engine does merging there.
- Changed test byteBuffer pools from on-heap to off-heap to work around
https://github.com/DataSketches/sketches-core/pull/116 for datasketches tests.
This patch introduces a GroupByStrategy concept and two strategies: "v1"
is the current groupBy strategy and "v2" is a new one. It also introduces
a merge buffers concept in DruidProcessingModule, to try to better
manage memory used for merging.
Both of these are described in more detail in #2987.
There are two goals of this patch:
1. Make it possible for historical/realtime nodes to return larger groupBy
result sets, faster, with better memory management.
2. Make it possible for brokers to merge streams when there are no order-by
columns, avoiding materialization.
This patch does not do anything to help with memory management on the broker
when there are order-by columns or when there are nested queries. That could
potentially be done in a future patch.
- Renumbered ApproximateHistogramAggregatorFactory from 8 to 12,
8 was taken by CardinalityAggregatorFactory
- Renumbered ApproximateHistogramFoldingAggregatorFactory from 9 to 13,
9 was taken by FilteredAggregatorFactory
* Eliminate exclusion groups from pull-deps
* Only consider dependency nodes in pull-deps if they are not in the following scopes
* provided
* test
* system
* Fix a bunch of `<scope>provided</scope>` missing tags
* Better exclusions for a couple of problematic libs