Struct EnforceDistRequirementRewriter 

struct EnforceDistRequirementRewriter {
    column_requirements: Vec<(HashSet<Column>, usize)>,
    cur_level: usize,
    plan_per_level: BTreeMap<usize, LogicalPlan>,
}

Implementation of the [TreeNodeRewriter] trait which is responsible for rewriting logical plans to enforce various requirement for distributed query.

Requirements enforced by this rewriter:

• Enforce column requirements for LogicalPlan::Projection nodes. Makes sure the required columns are available in the sub plan.

Fields

column_requirements: Vec<(HashSet<Column>, usize)>

only enforce column requirements after the expanding node in question, meaning only for node with cur_level <= level will consider adding those column requirements TODO(discord9): a simpler solution to track column requirements for merge scan

cur_level: usize

only apply column requirements >= cur_level this is used to avoid applying column requirements that are not needed for the current node, i.e. the node is not in the scope of the column requirements i.e, for this plan:

Aggregate: min(t.number)
  Projection: t.number

when on Projection node, we don’t need to apply the column requirements of Aggregate node because the Projection node is not in the scope of the Aggregate node

plan_per_level: BTreeMap<usize, LogicalPlan>

Implementations

impl EnforceDistRequirementRewriter

fn new( column_requirements: Vec<(HashSet<Column>, usize)>, cur_level: usize, ) -> Self

fn get_current_applicable_column_requirements( &self, node: &LogicalPlan, ) -> DfResult<BTreeMap<(Column, usize), BTreeSet<Column>>>

Return a mapping from (original column, level) to aliased columns in current node of all applicable column requirements i.e. only column requirements with level >= cur_level will be considered

Trait Implementations

impl Debug for EnforceDistRequirementRewriter

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

Formats the value using the given formatter.

impl TreeNodeRewriter for EnforceDistRequirementRewriter

type Node = LogicalPlan

The node type which is rewritable.

fn f_down(&mut self, node: Self::Node) -> DfResult<Transformed<Self::Node>>

Invoked while traversing down the tree before any children are rewritten. Default implementation returns the node as is and continues recursion.

fn f_up(&mut self, node: Self::Node) -> DfResult<Transformed<Self::Node>>

Invoked while traversing up the tree after all children have been rewritten. Default implementation returns the node as is and continues recursion.