adjust offset/hits if necessary to get enough input to global-phase reranking

1 files changed, 13 insertions, 2 deletions

diff --git a/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterSearcher.java b/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterSearcher.java
index f0222eea618..12f8cdf9852 100644
--- a/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterSearcher.java
+++ b/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterSearcher.java
@@ -244,13 +244,24 @@ public class ClusterSearcher extends Searcher {
             throw new IllegalStateException("perSchemaSearch must always be called with 1 schema, got: " + restrict.size());
         }
         String schema = restrict.iterator().next();
-        boolean useGlobalPhase = globalPhaseRanker != null;
+        int rerankCount = globalPhaseRanker != null ? globalPhaseRanker.getRerankCount(query, schema) : 0;
+        boolean useGlobalPhase = rerankCount > 0;
+        final int wantOffset = query.getOffset();
+        final int wantHits = query.getHits();
         if (useGlobalPhase) {
             var error = globalPhaseRanker.validateNoSorting(query, schema).orElse(null);
             if (error != null) return new Result(query, error);
+            int useHits = Math.max(wantOffset + wantHits, rerankCount);
+            query.setOffset(0);
+            query.setHits(useHits);
         }
         Result result = searcher.search(query, execution);
-        if (useGlobalPhase) globalPhaseRanker.rerankHits(query, result, schema);
+        if (useGlobalPhase) {
+            globalPhaseRanker.rerankHits(query, result, schema);
+            result.hits().trim(wantOffset, wantHits);
+            query.setOffset(wantOffset);
+            query.setHits(wantHits);
+        }
         return result;
     }