Dandandan commented on code in PR #7192:
URL: https://github.com/apache/arrow-datafusion/pull/7192#discussion_r1284065085
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datafusion/core/src/physical_optimizer/limit_aggregation.rs:
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@@ -0,0 +1,67 @@
+use std::sync::Arc;
+use datafusion_common::config::ConfigOptions;
+use crate::physical_optimizer::PhysicalOptimizerRule;
+use crate::physical_plan::ExecutionPlan;
+use crate::physical_plan::sorts::sort::SortExec;
+use datafusion_common::{DataFusionError, Result};
+use crate::physical_plan::aggregates::AggregateExec;
+
+pub struct LimitAggregation {
+
+}
+
+impl LimitAggregation {
+ pub fn new() -> Self {
+ Self {}
+ }
+
+ fn recurse(plan: Arc<dyn ExecutionPlan>) -> Result<Arc<dyn ExecutionPlan>>
{
+ if let Some(sort) = plan.as_any().downcast_ref::<SortExec>() {
+ let children = sort.children();
+ let child = match children.as_slice() {
+ [] => Err(DataFusionError::Execution("Sorts should have
children".to_string()))?,
+ [child] => child,
+ _ => Err(DataFusionError::Execution("Sorts should have 1
child".to_string()))?,
+ };
+ let binding = (*child).as_any();
+ if let Some(aggr) = binding.downcast_ref::<AggregateExec>() {
Review Comment:
I think we should only do this for accumulators like min/max combined with
respectively sorting asc/desc that give correct results under this optimization.
Are there other aggregation/sort combinations we expect?
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