Hello, I’m looking for a way to improve performance of a join query.
Suppose one joins two heterogeneous sources t1 and t2 with some predicates. Further assume that cardinality of one of the predicates is very low (compared cardinality of the second one). (How) Is it possible to convert second query (predicate) to include results (primary keys) of the first one (with low selectivity) ? Example select *from t1 left join t1 on (t1.id = t2.id)where t1.attr = 'foo' and t2.attr = 'bar' Let’s say that predicate t1.attr = 'foo' results in 3 rows (id=1, 2, 3). Will it be possible to rewrite t2 query to : select *from t2 where id in (1, 2, 3) and t2.attr = 'bar' I’m aware of existence of Metadata <https://calcite.apache.org/apidocs/org/apache/calcite/rel/metadata/Metadata.html> but not sure to use it. Any hits / directions are appreciated. Thanks, Andrei.
