Feng Zhu

[CALCITE-771] Use materialization for scan-project-sort query

3

As described in [CALCITE-771](https://issues.apache.org/jira/projects/CALCITE/issues/CALCITE-771), we add a rule to reuse the materialization defined as scan-project-sort.

As illustrated in [CALCITE-3514](https://issues.apache.org/jira/browse/CALCITE-3514), we need to implement `JdbcTable`'s `equals()` and `hashCode() `methods.

[CALCITE-3513] Unify TableFunction implementor's NullPolicy and its behavior

11

Details are illustrated in [CALCITE-3513](https://issues.apache.org/jira/browse/CALCITE-3513), Table function's implementation should be `NullPolicy.NONE`.

[CALCITE-3438] Validator should disallow use of the GROUPING function inside a FILTER clause

2

`AggVisitor` ignores to find grouping functions in default. However, for some cases we need to consider these functions. This PR adds an interface to control its beheavior, and tries for...

[CALCITE-3332] Query failed with AssertionError: cannot cast null as class java.math.BigDecima

3

Calcite runtime can process null semantic. However, the null literal is not properly handled when figuring out SqlMonotonicity, as demonstrated in [CALCITE-3332](https://issues.apache.org/jira/browse/CALCITE-3332).

[CALCITE-3088] Multi-groupsets query failed due to data type preservation check

1

The issue is described in [CALCITE-3088](https://issues.apache.org/jira/browse/CALCITE-3088). This kind of query is supported, for example, the case in **agg.iq** ``` # ROLLUP on 1 column select deptno + 1, count(*) as...