JavaScript Code Generator: Pushing down complex GB

With 0.0.5 release we are adding support for complex group by expressions using JavaScript Extraction Function. Sparklinedata would convert complex group by expressions to JavaScript using JavaScript Code Generator. Before to 0.0.5 complex group by expressions used to be executed in Spark; by pushing complex group by down to Druid the performance of the solution improves 2-3 times.

Following is an example of such expressions: select sum(c_acctbal) as bal from orderLineItemPartSupplier group by (substr(CAST(Date_Add(TO_DATE(CAST(CONCAT(TO_DATE(o_orderdate), 'T00:00:00.000') AS TIMESTAMP)), 5) AS TIMESTAMP), 0, 10))