2010YOUY01 commented on code in PR #21976:
URL: https://github.com/apache/datafusion/pull/21976#discussion_r3194201853
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datafusion/physical-optimizer/src/optimizer.rs:
##########
@@ -170,18 +169,12 @@ impl PhysicalOptimizer {
// those are handled by the later `FilterPushdown` rule.
// See `FilterPushdownPhase` for more details.
Arc::new(FilterPushdown::new()),
- // The EnforceDistribution rule is for adding essential
repartitioning to satisfy distribution
- // requirements. Please make sure that the whole plan tree is
determined before this rule.
- // This rule increases parallelism if doing so is beneficial to
the physical plan; i.e. at
- // least one of the operators in the plan benefits from increased
parallelism.
- Arc::new(EnforceDistribution::new()),
- // The CombinePartialFinalAggregate rule should be applied after
the EnforceDistribution rule
+ // EnsureRequirements: merged EnforceDistribution + EnforceSorting
into a
+ // single idempotent rule with distribution-aware pushdown_sorts.
+ // See https://github.com/apache/datafusion/issues/21973
Review Comment:
```suggestion
// Ensures each input plan satisfies the distribution and
ordering requirements
// declared by `ExecutionPlan::required_input_distribution` and
// `ExecutionPlan::required_input_ordering`.
// If the requirements are already satisfied, this rule leaves
the plan
// unchanged. For example, it does not add sorting when the
input is a file
// scan whose existing order already satisfies the required
ordering.
// Otherwise, this rule inserts the necessary repartitioning and
sorting
// operators.
// This used to be implemented as two separate rules:
`EnforceDistribution`
// and `EnforceSorting`. It is now a single idempotent rule with
// distribution-aware `pushdown_sorts`.
// See https://github.com/apache/datafusion/issues/21973.
```
Added more comments since this is the entry point.
I also have a question: What is this 'distribution-aware pushdown_sorts'? We
cloud link some reference to it.
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