* Remove SQL experimental banner and other doc adjustments.
Also,
- Adjust the ToC and other docs a bit so SQL and native queries are
presented on more equal footing.
- De-emphasize querying historicals and peons directly in the
native query docs. This is a really niche thing and may have been
confusing to include prominently in the very first paragraph.
- Remove DataSketches and Kafka indexing service from the experimental
features ToC. They are not experimental any longer and were there in
error.
* More notes.
* Slight tweak.
* Remove extra extra word.
* Remove RT node from ToC.
* Move scan-query from a contrib extension into core.
Based on a proposal at: https://groups.google.com/d/topic/druid-development/ME_OatUDnbk/discussion
This patch also adds support for virtual columns to the Scan query,
and updates Druid SQL to use Scan instead of Select.
This patch also makes some behavioral changes to handling of the __time
column. In particular, it is now is returned as "__time" rather than
"timestamp"; it is no longer included if you do not specifically ask for
it in your "columns"; and it is returned as a long rather than a string.
Users can revert time handling to the legacy extension behavior by
setting "legacy" : true in their queries, or setting the property
druid.query.scan.legacy = true. This is meant to provide a migration
path for users that were formerly using the contrib extension.
* Adjustments from review.
* Add back Select query.
* Adjust SQL docs.
* Restore SelectQuery link.
There result would be {"error"=>"Unknown exception",
"errorMessage"=>nil, "errorClass"=>"java.lang.NullPointerException",
"host"=>nil} when the json lack of 『granularity』.