org.apache.calcite.plan.SubstitutionVisitor.UnifyRule

public abstract static class SubstitutionVisitor.UnifyRule extends Object

Rule that attempts to match a query relational expression against a target relational expression.

The rule declares the query and target types; this allows the engine to fire only a few rules in a given context.

Field Details
- slotCount
  
  protected final int slotCount
- queryOperand
  
  protected final SubstitutionVisitor.Operand queryOperand
- targetOperand
  
  protected final SubstitutionVisitor.Operand targetOperand
Constructor Details
- UnifyRule
  
  protected UnifyRule(int slotCount, SubstitutionVisitor.Operand queryOperand, SubstitutionVisitor.Operand targetOperand)
Method Details
- apply
  
  protected abstract @Nullable SubstitutionVisitor.UnifyResult apply(SubstitutionVisitor.UnifyRuleCall call)
  Applies this rule to a particular node in a query. The goal is to convert query into target. Before the rule is invoked, Calcite has made sure that query's children are equivalent to target's children.
  There are 3 possible outcomes:
  
  query already exactly matches target; returns target
  
  query is sufficiently close to a match for target; returns target
  
  query cannot be made to match target; returns null
  
  REVIEW: Is possible that we match query PLUS one or more of its ancestors?
  Parameters:
  
  call - Input parameters
- match
  
  protected @Nullable SubstitutionVisitor.UnifyRuleCall match(SubstitutionVisitor visitor, MutableRel query, MutableRel target)
- copy
  
  protected <E> com.google.common.collect.ImmutableList<E> copy(E[] slots, int slotCount)

Class SubstitutionVisitor.UnifyRule

Field Summary