Struct VariableOrder 

pub struct VariableOrder {
    pub leader_idx: u8,
    pub lookup_perms: Vec<LookupPerm>,
    pub kernel_output_cols: Vec<ProjectExpr>,
    pub kclique: Option<KCliqueVariableOrder>,
}

Variable-ordering decision attached to a MultiWayJoin.

None on the parent variant preserves legacy triangle, 4-cycle, and recursive dispatch behavior bit-identically (default leader, no col-swap, no kernel projection — output_columns carries the binary-fallback projection as before).

When Some, the dispatcher consumes leader_idx to rotate the kernel inputs, applies any lookup_perms col-swaps, and post-projects the kernel-direct output buffer through kernel_output_cols. MultiWayJoin::output_columns stays untouched so binary-fallback consumers continue reading it directly.

Fields

leader_idx: u8

Selected leader’s index in the canonical promoter input order (e.g., for triangle: 0=e_xy, 1=e_yz, 2=e_xz). 0 reproduces the default leader.

lookup_perms: Vec<LookupPerm>

One entry per non-leader lookup input, in dispatcher slot order.

kernel_output_cols: Vec<ProjectExpr>

Permutation applied to the kernel-direct output buffer to produce head-ordered columns. For default leader this would be identity but the field is omitted (var_order = None) — the legacy triangle/4-cycle path keeps using MultiWayJoin::output_columns directly.

kclique: Option<KCliqueVariableOrder>

Full K-clique variable-order plan for K=5..K=8. None preserves the legacy triangle/4-cycle leader-permutation path.

Implementations

impl VariableOrder

pub fn legacy( leader_idx: u8, lookup_perms: Vec<LookupPerm>, kernel_output_cols: Vec<ProjectExpr>, ) -> Self

Creates the legacy triangle/4-cycle leader-permutation form.

pub fn kclique(kclique: KCliqueVariableOrder) -> Self

Creates the full K-clique variable-order form.

Trait Implementations

impl Clone for VariableOrder

fn clone(&self) -> VariableOrder

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for VariableOrder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for VariableOrder

fn eq(&self, other: &VariableOrder) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for VariableOrder