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UpdateCTERelationStats Logical Optimization

UpdateCTERelationStats is a logical optimization that updateCTEStats for CTE logical operators.

UpdateCTERelationStats is part of the Update CTE Relation Stats once-executed batch in the standard batches of the Logical Optimizer.

UpdateCTERelationStats is simply a Catalyst rule for transforming logical plans (Rule[LogicalPlan]).

Executing Rule

apply(
  plan: LogicalPlan): LogicalPlan

apply does nothing and simply returns the given LogicalPlan when applied to a Subquery or a non-CTE query plan. Otherwise, apply updateCTEStats.

apply is part of the Rule abstraction.

updateCTEStats

updateCTEStats(
  plan: LogicalPlan,
  statsMap: mutable.HashMap[Long, Statistics]): LogicalPlan

updateCTEStats branches off based on the type of the logical operator:

  1. WithCTE
  2. CTERelationRef
  3. Others with CTE tree pattern

For all other types, updateCTEStats returns the given LogicalPlan.

updateCTEStats is a recursive function.

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