Push down topk through join

datafusion/optimizer/src/lib.rs

@@ -65,6 +65,7 @@ pub mod optimizer;
 pub mod propagate_empty_relation;
 pub mod push_down_filter;
 pub mod push_down_limit;
+pub mod push_down_topk_through_join;
 pub mod replace_distinct_aggregate;
 pub mod rewrite_set_comparison;
 pub mod scalar_subquery_to_join;

datafusion/optimizer/src/optimizer.rs

@@ -51,6 +51,7 @@ use crate::plan_signature::LogicalPlanSignature;
 use crate::propagate_empty_relation::PropagateEmptyRelation;
 use crate::push_down_filter::PushDownFilter;
 use crate::push_down_limit::PushDownLimit;
+use crate::push_down_topk_through_join::PushDownTopKThroughJoin;
 use crate::replace_distinct_aggregate::ReplaceDistinctWithAggregate;
 use crate::rewrite_set_comparison::RewriteSetComparison;
 use crate::scalar_subquery_to_join::ScalarSubqueryToJoin;
@@ -296,6 +297,7 @@ impl Optimizer {
             Arc::new(EliminateOuterJoin::new()),
             // Filters can't be pushed down past Limits, we should do PushDownFilter after PushDownLimit
             Arc::new(PushDownLimit::new()),
+            Arc::new(PushDownTopKThroughJoin::new()),
             Arc::new(PushDownFilter::new()),
             Arc::new(SingleDistinctToGroupBy::new()),
             // The previous optimizations added expressions and projections,