Method join

src/expr/src/relation.rs:1292–1305

Performs a relational equijoin among the input collections. The sequence `inputs` each describe different input collections, and the sequence `variables` describes equality constraints that some of their columns must satisfy. Each element in `variable` describes a set of pairs `(input_index, column_index)` where every value described by that set must be equal. For example, the pair `(input, col

(inputs: Vec<MirRelationExpr>, variables: Vec<Vec<(usize, usize)>>)

    /// let result = joined.project(vec![0, 1, 3]);
    /// ```
    pub fn join(inputs: Vec<MirRelationExpr>, variables: Vec<Vec<(usize, usize)>>) -> Self {
        let input_mapper = join_input_mapper::JoinInputMapper::new(&inputs);

        let equivalences = variables
            .into_iter()
            .map(|vs| {
                vs.into_iter()
                    .map(|(r, c)| input_mapper.map_expr_to_global(MirScalarExpr::column(c), r))
                    .collect::<Vec<_>>()
            })
            .collect::<Vec<_>>();

        Self::join_scalars(inputs, equivalences)
    }

    /// Constructs a join operator from inputs and required-equal scalar expressions.
    pub fn join_scalars(