Gian Merlino

Very cool! Thanks @AlexanderSaydakov! Has this code been used in a production environment? Any gotches we should know about? There appears to be a legitimate issue in `KllDoublesSketchAggregatorTest.buildingSketchesAtQueryTime` when SQL-compatible...

FYI I haven't had a chance to take a look at this but it is in my queue. If anyone gets to review it before I do then thanks!

Two test runs failed with the below segfault in `KllDoublesSketchAggregatorTest` ([first time](https://app.travis-ci.com/github/apache/druid/jobs/580645782)) and `KllFloatsSketchAggregatorTest` ([second time](https://app.travis-ci.com/github/apache/druid/jobs/580645784)). Judging by the fact it's `BaseWritableMemoryImpl.getNativeOrderedLong`, it could be an out-of-bound access or a...

So close! There's a conflict in ColumnType, probably from https://github.com/apache/druid/pull/12914, which was a response to the discussion in this PR about better supporting the arrays returned by the KLL postaggs....

Hmm. Another crash. ``` # # A fatal error has been detected by the Java Runtime Environment: # # SIGSEGV (0xb) at pc=0x00007f193747fdac, pid=21257, tid=0x00007f194d6bd700 # # JRE version: OpenJDK...

I suspect the additional crash was due to a similar problem, but for unions. I pushed https://github.com/apache/druid/pull/12498/commits/7e117c72c86373027b39b701dd965d164716af52 to the branch which will copy those too. @AlexanderSaydakov if there's a better...

Looks like the latest build passed tests. I'll merge it. Thanks @AlexanderSaydakov !

Some things we'll need to tackle: 1. [Strong encapsulation](https://dev.java/learn/strong-encapsulation-\(of-jdk-internals\)/) in Java 17 means that Druid requires various `--add-opens` and `--add-exports` parameters in order to function. Skipping these parameters leads to...

Patch #12839 adds the relevant strong-encapsulation-related parameters to the command line when the Java version is >= 17, and updates the unit tests to run on Java 17 instead of...

#12987 dodges the incompatibility between DataSketches Memory and JDK17. After speaking with the DataSketches team I learned it's safe to use the current version of DataSketches (and future 8+11 compatible...