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[core] Skip TopN pushdown when a non-partition filter is present#8458

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Merged
JingsongLi merged 1 commit into from
Jul 4, 2026
Merged

[core] Skip TopN pushdown when a non-partition filter is present #8458

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4 changes: 3 additions & 1 deletion paimon-core/src/main/java/org/apache/paimon/table/source/DataTableBatchScan.java
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Original file line numberDiff line numberDiff line change
Expand Up@@ -188,9 +188,11 @@ private Optional<StartingScanner.Result> applyPushDownLimit() {
}

private Optional<StartingScanner.Result> applyPushDownTopN() {
// Auth drops rows at read time, so split-level TopN pruning could drop authorized rows.
// A read-time filter (WHERE or auth) drops rows after split pruning, so split-level TopN
// pruning could keep too few splits. Skip it when either is present.
if (topN == null
|| pushDownLimit != null
|| snapshotReader.hasNonPartitionFilter()
|| authHasNonPartitionFilter
|| !schema.primaryKeys().isEmpty()) {
return Optional.empty();
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19 changes: 19 additions & 0 deletions paimon-core/src/test/java/org/apache/paimon/table/source/TableScanTest.java
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Original file line numberDiff line numberDiff line change
Expand Up@@ -421,6 +421,25 @@ public void testPushDownTopN() throws Exception {
.isEqualTo(60);
assertThat(((DataSplit) splits2.get(2)).nullCount(field.id(), evolutions)).isEqualTo(2);

// A non-partition filter must disable TopN pushdown, else it prunes splits by sort-column
// stats unaware the filter removes rows. "b" >= 0 matches every row, so all 9 splits are
// kept instead of pruned to 3.
PredicateBuilder builder = new PredicateBuilder(table.rowType());
TableScan.Plan planWithFilter =
table.newScan()
.withFilter(builder.greaterOrEqual(2, 0L))
.withTopN(new TopN(ref, ASCENDING, NULLS_FIRST, 1))
.plan();
assertThat(planWithFilter.splits().size()).isEqualTo(9);

// A partition-only filter keeps TopN pushdown enabled (surviving rows all pass): still 3.
TableScan.Plan planWithPartitionFilter =
table.newScan()
.withFilter(builder.greaterOrEqual(0, 0))
.withTopN(new TopN(ref, ASCENDING, NULLS_FIRST, 1))
.plan();
assertThat(planWithPartitionFilter.splits().size()).isEqualTo(3);

// with bottom1 null last
TableScan.Plan plan3 =
table.newScan().withTopN(new TopN(ref, ASCENDING, NULLS_LAST, 1)).plan();
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