Method filter

src/expr/src/relation.rs:1206–1231

Retain only the rows satisfying each of several predicates.

(mut self, predicates: I)

    /// Retain only the rows satisfying each of several predicates.
    pub fn filter<I>(mut self, predicates: I) -> Self
    where
        I: IntoIterator<Item = MirScalarExpr>,
    {
        // Extract existing predicates
        let mut new_predicates = if let MirRelationExpr::Filter { input, predicates } = self {
            self = *input;
            predicates
        } else {
            Vec::new()
        };
        // Normalize collection of predicates.
        new_predicates.extend(predicates);
        new_predicates.retain(|p| !p.is_literal_true());
        new_predicates.sort();
        new_predicates.dedup();
        // Introduce a `Filter` only if we have predicates.
        if !new_predicates.is_empty() {
            self = MirRelationExpr::Filter {
                input: Box::new(self),
                predicates: new_predicates,
            };
        }

        self
    }

    /// Form the Cartesian outer-product of rows in both inputs.
    pub fn product(mut self, right: Self) -> Self {