Method filter

src/transform/src/analysis.rs:1710–1735

(
            &self,
            predicates: &Vec<MirScalarExpr>,
            keys: &Vec<Vec<usize>>,
            input: CardinalityEstimate,
        )

        }

        fn filter(
            &self,
            predicates: &Vec<MirScalarExpr>,
            keys: &Vec<Vec<usize>>,
            input: CardinalityEstimate,
        ) -> CardinalityEstimate {
            // TODO(mgree): should we try to do something for indices built on multiple columns?
            let mut unique_columns = BTreeSet::new();
            for key in keys {
                if key.len() == 1 {
                    unique_columns.insert(key[0]);
                }
            }

            let mut estimate = input;
            for expr in predicates {
                let selectivity = self.predicate(expr, &unique_columns);
                debug_assert!(
                    OrderedFloat(0.0) <= selectivity && selectivity <= OrderedFloat(1.0),
                    "predicate selectivity {selectivity} should be in the range [0,1]"
                );
                estimate = estimate * selectivity.0;
            }

            estimate
        }

        fn join(
            &self,