druid/extensions-core/histogram
Gian Merlino d51f5e058d SQL: Ditch CalciteConnection layer and add DruidMeta, extension aggregators. (#3852)
* SQL: Ditch CalciteConnection layer and add DruidMeta, extension aggregators.

Switched from CalciteConnection to Planner, bringing benefits:

- CalciteConnection's JDBC interface no longer sits between the SQL server
  (HTTP/Avatica) and Druid's query layer. Instead, the SQL servers can use
  Druid Sequence objects directly, reducing overhead in the query return path.

- Implemented our own Planner-based Avatica Meta, letting us control
  connection timeouts and connection / statement limits. The previous
  CalciteConnection-based implementation didn't have any limits or timeouts.

- The Planner interface lets us override the operator table, opening up
  SQL language extensions. This patch includes two: APPROX_COUNT_DISTINCT
  in core, and a QUANTILE aggregator in the druid-histogram extension.

Also:

- Added INFORMATION_SCHEMA metadata schema.

- Added tests for Unicode literals and escapes.

* Verify statement is actually open before closing it.

* More detailed INFORMATION_SCHEMA docs.
2017-01-19 16:32:20 -08:00
..
src SQL: Ditch CalciteConnection layer and add DruidMeta, extension aggregators. (#3852) 2017-01-19 16:32:20 -08:00
pom.xml SQL: Ditch CalciteConnection layer and add DruidMeta, extension aggregators. (#3852) 2017-01-19 16:32:20 -08:00