Hi,
In Quark, we have tried to optimize join queries using auto detection of
materialised views. For instance, when we have materialised view of  table
'X' named 'X_part' defined by query: " select * from X where X.a >
'2016-01-01' " then we expect following query to be optimised by 'X_part':

select * from X inner join Y on X.id = Y.xid inner join Z on Y.id=Z.yid
where X.a > '2016-02-02' and Y.b = "Bangalore"

There were couple of changes required to do this:
1. Add a new Rule for Filter on TableScan. Basically, after predicate has
been pushed through join onto table scan, new rule checks if it can be
optimised by Materialised View.
https://github.com/qubole/quark/blob/master/optimizer/src/main/java/com/qubole/quark/planner/MaterializedViewFilterScanRule.java

2. Add a new Unify rule to MaterialisedSubstitutionVisitor:
https://github.com/qubole/incubator-calcite/commit/2d031d14d23810291377d92dc5ef2eaa515d35b7

If this change will be useful for Calcite, then I can raise relevant PR
with test cases to contribute it back. Just let us know.

Regards,
Amogh

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