Backport ES|QL: Pass fixed size instead of maxPageSize (#135767)

docs/changelog/135767.yaml

@@ -0,0 +1,5 @@
+pr: 135767
+summary: Pass fix size instead of `maxPageSize` to `LuceneTopNOperator` scorer
+area: ES|QL
+type: bug
+issues: []

x-pack/plugin/esql/compute/src/main/java/org/elasticsearch/compute/lucene/LuceneTopNSourceOperator.java

@@ -119,6 +119,9 @@ public String describe() {
         }
     }
 
+    // We use the same value as the INITIAL_INTERVAL from CancellableBulkScorer
+    private static final int NUM_DOCS_INTERVAL = 1 << 12;
+
     private final CircuitBreaker breaker;
     private final List<SortBuilder<?>> sorts;
     private final long estimatedPerRowSortSize;
@@ -202,7 +205,7 @@ private Page collect() throws IOException {
                 perShardCollector = newPerShardCollector(scorer.shardContext(), sorts, needsScore, limit);
             }
             var leafCollector = perShardCollector.getLeafCollector(scorer.leafReaderContext());
-            scorer.scoreNextRange(leafCollector, scorer.leafReaderContext().reader().getLiveDocs(), maxPageSize);
+            scorer.scoreNextRange(leafCollector, scorer.leafReaderContext().reader().getLiveDocs(), NUM_DOCS_INTERVAL);
         } catch (CollectionTerminatedException cte) {
             // Lucene terminated early the collection (doing topN for an index that's sorted and the topN uses the same sorting)
             scorer.markAsDone();

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/EsqlActionTaskIT.java

@@ -511,7 +511,7 @@ public void testTaskContentsForTopNQuery() throws Exception {
         try {
             getTasksStarting();
             logger.info("unblocking script");
-            scriptPermits.release(pageSize());
+            scriptPermits.release(numberOfDocs() + pageSize());
             List<TaskInfo> tasks = getTasksRunning();
             String sortStatus = """
                 [{"pause_me":{"order":"asc","missing":"_last","unmapped_type":"long"}}]""";