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Make limit pushdown work for SortPreservingMergeExec #17893

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Merged
merged 3 commits into from
Oct 3, 2025
Merged

Make limit pushdown work for SortPreservingMergeExec #17893

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969468b
Make limit pushdown work for sortpreservingmerge
Dandandan Oct 3, 2025
caa9a9a
Remove test
Dandandan Oct 3, 2025
63311a1
datafusion/physical-optimizer/src/limit_pushdown_past_window.rs
Dandandan Oct 3, 2025
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17 changes: 17 additions & 0 deletions datafusion/physical-optimizer/src/limit_pushdown_past_window.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ use datafusion_expr::{WindowFrameBound, WindowFrameUnits};
use datafusion_physical_plan::execution_plan::CardinalityEffect;
use datafusion_physical_plan::limit::GlobalLimitExec;
use datafusion_physical_plan::sorts::sort::SortExec;
use datafusion_physical_plan::sorts::sort_preserving_merge::SortPreservingMergeExec;
use datafusion_physical_plan::windows::BoundedWindowAggExec;
use datafusion_physical_plan::ExecutionPlan;
use std::cmp;
Expand Down Expand Up @@ -91,6 +92,22 @@ impl PhysicalOptimizerRule for LimitPushPastWindows {
return Ok(Transformed::no(node));
}

// Apply the limit if we hit a sortpreservingmerge node
if let Some(spm) = node.as_any().downcast_ref::<SortPreservingMergeExec>() {
let latest = latest_limit.take();
let Some(fetch) = latest else {
latest_max = 0;
return Ok(Transformed::no(node));
};
let fetch = match spm.fetch() {
None => fetch + latest_max,
Some(existing) => cmp::min(existing, fetch + latest_max),
};
let spm: Arc<dyn ExecutionPlan> = spm.with_fetch(Some(fetch)).unwrap();
latest_max = 0;
return Ok(Transformed::complete(spm));
}

// Apply the limit if we hit a sort node
if let Some(sort) = node.as_any().downcast_ref::<SortExec>() {
let latest = latest_limit.take();
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4 changes: 2 additions & 2 deletions datafusion/sqllogictest/test_files/window.slt
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Original file line number Diff line number Diff line change
Expand Up @@ -5966,8 +5966,8 @@ physical_plan
01)ProjectionExec: expr=[c1@2 as c1, c2@3 as c2, sum(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW@4 as sum1, sum(test.c2) FILTER (WHERE test.c2 >= Int64(2) AND test.c2 < Int64(4) AND test.c1 > Int64(0)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW@5 as sum2, count(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW@6 as count1, array_agg(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW@7 as array_agg1, array_agg(test.c2) FILTER (WHERE test.c2 >= Int64(2) AND test.c2 < Int64(4) AND test.c1 > Int64(0)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW@8 as array_agg2]
02)--GlobalLimitExec: skip=0, fetch=5
03)----BoundedWindowAggExec: wdw=[sum(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW: Field { name: "sum(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW", data_type: Int64, nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }, frame: ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW, sum(test.c2) FILTER (WHERE test.c2 >= Int64(2) AND test.c2 < Int64(4) AND test.c1 > Int64(0)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW: Field { name: "sum(test.c2) FILTER (WHERE test.c2 >= Int64(2) AND test.c2 < Int64(4) AND test.c1 > Int64(0)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW", data_type: Int64, nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }, frame: ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW, count(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW: Field { name: "count(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW", data_type: Int64, nullable: false, dict_id: 0, dict_is_ordered: false, metadata: {} }, frame: ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW, array_agg(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW: Field { name: "array_agg(test.c2) FILTER (WHERE test.c2 >= Int64(2)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW", data_type: List(Field { name: "item", data_type: Int64, nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }), nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }, frame: ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW, array_agg(test.c2) FILTER (WHERE test.c2 >= Int64(2) AND test.c2 < Int64(4) AND test.c1 > Int64(0)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW: Field { name: "array_agg(test.c2) FILTER (WHERE test.c2 >= Int64(2) AND test.c2 < Int64(4) AND test.c1 > Int64(0)) ORDER BY [test.c1 ASC NULLS LAST, test.c2 ASC NULLS LAST] ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW", data_type: List(Field { name: "item", data_type: Int64, nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }), nullable: true, dict_id: 0, dict_is_ordered: false, metadata: {} }, frame: ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW], mode=[Sorted]
04)------SortPreservingMergeExec: [c1@2 ASC NULLS LAST, c2@3 ASC NULLS LAST]
05)--------SortExec: expr=[c1@2 ASC NULLS LAST, c2@3 ASC NULLS LAST], preserve_partitioning=[true]
04)------SortPreservingMergeExec: [c1@2 ASC NULLS LAST, c2@3 ASC NULLS LAST], fetch=5
05)--------SortExec: TopK(fetch=5), expr=[c1@2 ASC NULLS LAST, c2@3 ASC NULLS LAST], preserve_partitioning=[true]
06)----------ProjectionExec: expr=[__common_expr_3@0 as __common_expr_1, __common_expr_3@0 AND c2@2 < 4 AND c1@1 > 0 as __common_expr_2, c1@1 as c1, c2@2 as c2]
07)------------ProjectionExec: expr=[c2@1 >= 2 as __common_expr_3, c1@0 as c1, c2@1 as c2]
08)--------------DataSourceExec: file_groups={4 groups: [[WORKSPACE_ROOT/datafusion/core/tests/data/partitioned_csv/partition-0.csv], [WORKSPACE_ROOT/datafusion/core/tests/data/partitioned_csv/partition-1.csv], [WORKSPACE_ROOT/datafusion/core/tests/data/partitioned_csv/partition-2.csv], [WORKSPACE_ROOT/datafusion/core/tests/data/partitioned_csv/partition-3.csv]]}, projection=[c1, c2], file_type=csv, has_header=false
Expand Down