Struct mz_sql::plan::lowering::OnPredicates

struct OnPredicates {
    predicates: Vec<OnPredicate>,
    oa: usize,
}

A struct that represents the predicates in the on clause in a form suitable for efficient planning outer joins with equijoin predicates.

Fields

predicates: Vec<OnPredicate>

A store for classified ON predicates.

Predicates that reference a single side are adjusted to assume an outer × <side> schema.

oa: usize

Number of outer context columns.

Implementations

impl OnPredicates

const I_OUT: usize = 0usize

const I_LHS: usize = 1usize

const I_RHS: usize = 2usize

const I_SUB: usize = 3usize

fn new( oa: usize, la: usize, ra: usize, sa: usize, on: Vec<MirScalarExpr>, _context: &Context<'_>, ) -> Self

Classify the predicates in the on clause of an outer join.

The other parameters are arities of the input parts:

• oa is the arity of the outer context.
• la is the arity of the left input.
• ra is the arity of the right input.
• sa is the arity of the on subqueries.

The constructor assumes that:

1. The on parameter will be applied on a result that has the following schema outer × left × right × on_subqueries.
2. The on parameter is already adjusted to assume that schema.
3. The on parameter is obtained by canonicalizing the original on: MirScalarExpr with canonicalize_predicates.

fn is_equijoin(&self, context: &Context<'_>) -> bool

Check if the predicates can be lowered with an equijoin-based strategy.

fn join_keys(&self) -> JoinKeys

Return an MirRelationExpr list that represents the keys for the equijoin. The list will contain the outer columns as a prefix.

fn eq_lhs(&self) -> impl Iterator<Item = MirScalarExpr> + '_

Return an iterator over the left-hand sides of all OnPredicate::Eq conditions in the predicates list.

The iterator will start with column references to the outer columns as a prefix.

fn eq_rhs(&self) -> impl Iterator<Item = MirScalarExpr> + '_

Return an iterator over the right-hand sides of all OnPredicate::Eq conditions in the predicates list.

The iterator will start with column references to the outer columns as a prefix.

fn lhs(&self) -> impl Iterator<Item = MirScalarExpr> + '_

Return an iterator over the OnPredicate::Lhs, OnPredicate::LhsConsequence and OnPredicate::Const conditions in the predicates list.

fn rhs(&self) -> impl Iterator<Item = MirScalarExpr> + '_

Return an iterator over the OnPredicate::Rhs, OnPredicate::RhsConsequence and OnPredicate::Const conditions in the predicates list.