Module datafusion::physical_optimizer::sort_enforcement

EnforceSorting optimizer rule inspects the physical plan with respect to local sorting requirements and does the following:

• Adds a SortExec when a requirement is not met,
• Removes an already-existing SortExec if it is possible to prove that this sort is unnecessary The rule can work on valid and invalid physical plans with respect to sorting requirements, but always produces a valid physical plan in this sense.

A non-realistic but easy to follow example for sort removals: Assume that we somehow get the fragment

SortExec: expr=[nullable_col@0 ASC]
  SortExec: expr=[non_nullable_col@1 ASC]

in the physical plan. The first sort is unnecessary since its result is overwritten by another SortExec. Therefore, this rule removes it from the physical plan.

Structs

• EnforceSorting
  This rule inspects SortExec’s in the given physical plan and removes the ones it can prove unnecessary.