Time column predicates are invalidating use of star-tree indices

[subourbonite]

In some cases, time-column predicates are disqualifying queries from using star-trees, when they would otherwise be used. Specifically, this appears to be the case when using a dynamic timestamp comparison against the now() operator:

SELECT dimension, SUM(metric) AS totalMetrics FROM myTable WHERE otherDimension='filterValue' AND eventTimestamp >= cast(now() - 172800000 as long) GROUP BY 1 ORDER BY 2 DESC LIMIT 10

where a query that uses a static value for timestamp comparison will use a star-tree:
SELECT dimension, SUM(metric) AS totalMetrics FROM myTable WHERE otherDimension='filterValue' AND eventTimestamp >= 1611161288000 GROUP BY 1 ORDER BY 2 DESC LIMIT 10

Thanks to @mayankshriv, I'll try to put together a PR to address.

[Jackie-Jiang]

This is unexpected. cast(now() - 172800000 as long) should be replaced with the actual value on the broker side, and these 2 queries should be identical on the server side. @fx19880617 Can you confirm?

[mayankshriv]

I did a simple test to compile the query to BrokerRequest, and do see cast(now() - 172800000 as long) as LHS. My test did not actually go through any query execution.

[Jackie-Jiang]

The problem is that we don't have a scalar function implementation of cast(), thus it won't be resolved at compilation

[SandishKumarHN]

@Jackie-Jiang will work on adding a scalar function for cast() based on your suggestion offline.