Skip to content

[CALCITE-7557] Linq4j.ListEnumerable.take(int) / skip(int) diverge from EnumerableDefaults on negative counts #5124

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
mihaibudiu merged 1 commit into from
Jul 27, 2026
+28 −4
Merged

[CALCITE-7557] Linq4j.ListEnumerable.take(int) / skip(int) diverge from EnumerableDefaults on negative counts #5124

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
16 changes: 12 additions & 4 deletions linq4j/src/main/java/org/apache/calcite/linq4j/Linq4j.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -587,10 +587,14 @@ static class ListEnumerable<T> extends CollectionEnumerable<T> {

@Override public Enumerable<T> skip(int count) {
final List<T> list = toList();
if (count >= list.size()) {
// Clamp to zero, as the BigDecimal overload does, so that a negative
// count skips nothing and matches EnumerableDefaults.skip rather than
// throwing from List.subList.
final int rows = Math.max(count, 0);
if (rows >= list.size()) {
return Linq4j.emptyEnumerable();
}
return new ListEnumerable<>(list.subList(count, list.size()));
return new ListEnumerable<>(list.subList(rows, list.size()));
}

@Override public Enumerable<T> skip(BigDecimal count) {
Expand All @@ -605,10 +609,14 @@ static class ListEnumerable<T> extends CollectionEnumerable<T> {

@Override public Enumerable<T> take(int count) {
final List<T> list = toList();
if (count >= list.size()) {
// Clamp to zero, as the BigDecimal overload does, so that a negative
// count yields an empty enumerable and matches EnumerableDefaults.take
// rather than throwing from List.subList.
final int rows = Math.max(count, 0);
if (rows >= list.size()) {
return this;
}
return new ListEnumerable<>(list.subList(0, count));
return new ListEnumerable<>(list.subList(0, rows));
}

@Override public Enumerable<T> take(BigDecimal count) {
Expand Down
16 changes: 16 additions & 0 deletions linq4j/src/test/java/org/apache/calcite/linq4j/test/Linq4jTest.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2238,4 +2238,20 @@ public String toString() {
new Department("HR", 20, ImmutableList.of()),
new Department("Marketing", 30, ImmutableList.of(emps[1])),
};

@Test void testTakeListEnumerableNegativeSize() {

@mihaibudiu mihaibudiu Jul 27, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Can this be reflected in some SQL tests as well? What happens for SELECT * LIMIT -2.5?

final List<Integer> values = Arrays.asList(1, 2, 3);

assertThat(EnumerableDefaults.take(Linq4j.asEnumerable(values), -1).toList(),
is(empty()));
assertThat(Linq4j.asEnumerable(values).take(-1).toList(), is(empty()));
}

@Test void testSkipListEnumerableNegativeSize() {
final List<Integer> values = Arrays.asList(1, 2, 3);

assertThat(EnumerableDefaults.skip(Linq4j.asEnumerable(values), -1).toList(),
is(values));
assertThat(Linq4j.asEnumerable(values).skip(-1).toList(), is(values));
}
}
Loading