**Build scan:**
https://gradle-enterprise.elastic.co/s/mex3fmuu2orxu/tests/:x-pack:plugin:esql:compute:test/org.elasticsearch.compute.operator.topn.TopNOperatorTests/testSimpleSmallInput

**Reproduction line:**
```
./gradlew ':x-pack:plugin:esql:compute:test' --tests "org.elasticsearch.compute.operator.topn.TopNOperatorTests.testSimpleSmallInput" -Dtests.seed=822395B061122671 -Dtests.locale=sq -Dtests.timezone=America/Aruba -Druntime.java=21
```

**Applicable branches:**
main

**Reproduces locally?:**
Yes

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.compute.operator.topn.TopNOperatorTests&tests.test=testSimpleSmallInput

**Failure excerpt:**
```
java.lang.AssertionError: 
Expected: <0L>
     but: was <1920L>

  at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
  at org.junit.Assert.assertThat(Assert.java:956)
  at org.junit.Assert.assertThat(Assert.java:923)
  at org.elasticsearch.compute.operator.OperatorTestCase.assertSimple(OperatorTestCase.java:173)
  at org.elasticsearch.compute.operator.OperatorTestCase.testSimpleSmallInput(OperatorTestCase.java:70)
  at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
  at java.lang.reflect.Method.invoke(Method.java:580)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:48)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:843)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:490)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:850)
  at java.lang.Thread.run(Thread.java:1583)

```
x-pack/plugin/esql/compute/src/test/java/org/elasticsearch/compute/operator/CannedSourceOperator.java
Page first = pages.get(0);
        Block.Builder[] builders = new Block.Builder[first.getBlockCount()];
        for (int b = 0; b < builders.length; b++) {
            builders[b] = first.getBlock(b).elementType().newBlockBuilder(totalPositions);
        }
        for (Page p : pages) {
            for (int b = 0; b < builders.length; b++) {
                builders[b].copyFrom(p.getBlock(b), 0, p.getPositionCount());
            }
        }
        Block[] blocks = new Block[builders.length];
        for (int b = 0; b < blocks.length; b++) {
            blocks[b] = builders[b].build();
        }
        return new Page(blocks);
    }
    /**
     * Make a deep copy of some pages. Useful so that when the originals are
     * released the copies are still live.
     */
    public static List<Page> deepCopyOf(List<Page> pages) {
        List<Page> out = new ArrayList<>(pages.size());
        for (Page p : pages) {
            Block[] blocks = new Block[p.getBlockCount()];
            for (int b = 0; b < blocks.length; b++) {
                Block orig = p.getBlock(b);
                Block.Builder builder = orig.elementType().newBlockBuilder(p.getPositionCount());
                builder.copyFrom(orig, 0, p.getPositionCount());
                blocks[b] = builder.build();
            }