* Add SQL GROUPING SETS support.
Built on top of the subtotalsSpec feature in the groupBy query. This also involves
two changes to subtotalsSpec:
- Alter behavior so limitSpec is applied after subtotalsSpec, rather than applied to
each grouping set. This is more in line with SQL standard behavior. I think it is okay
to make this change, since the old behavior was not documented, so users should
hopefully not be depending on it.
- Fix a bug where virtual columns were included in the subtotal queries, but they
should not have been.
Also fixes two bugs in query equality checking:
- BaseQuery: Use getDuration() instead of "duration" in equals and hashCode, since the
latter is lazily initialized and might be null in one query but not the other.
- GroupByQuery: Include subtotalsSpec in equals and hashCode.
* Fix bugs.
* Fix tests.
* PR updates.
* Grouping class hygiene.
* implement shell for greatest sql aggregator with hardcoded long values
* implement functional long greatest aggregator for direct access columns
* implement greatest & least sql aggregators for long & double types using abstract base class
* add javadocs, unit tests & handling for floats for greatest/least postaggregations
* minor checkstyle fix
* improve naming for the test cases
* make inner class static
* remove blank lines to retest travis build
* change trivial text to rerun travis build
* implement suggested updates for greatest/least sql aggs & fix checkstyle issues
* fix stale comments in greatest/least sql aggs abstract base
* Update sql.md
* improve sql function definitions for greatest/least sql aggs
* add more tests for greatest/least sql aggs
* add tests to cover invalid greatest/least sql expressions
* rename & reorder greatest least sql tests
* null handling for numeric first/last aggregators, refactor to not extend nullable numeric agg since they are complex typed aggs
* initially null or not based on config
* review stuff, make string first/last consistent with null handling of numeric columns, more tests
* docs
* handle nil selectors, revert to primitive first/last types so groupby v1 works...
* SQL: EARLIEST, LATEST aggregators.
I chose these names instead of FIRST, LAST because those are already
reserved functions in Calcite that mean something different. I think
these are also better names anyway.
* Finalify.
* SQL updates.
* Adjust aggregator calls.
* Validations, test updates.
* Review docs.
* Add group_id to overlord tasks API and sys.tasks table
* adjust test
* modify docs
* Make groupId nullable
* fix integration test
* fix toString
* Remove groupId from TaskInfo
* Modify docs and tests
* modify TaskMonitorTest
Gian Merlino
Clint Wylie
Maytas Monsereenusorn
Aditya
Jonathan Wei
Surekha
Chi Cao Minh