Remove confidence based streaming

Signed-off-by: Atri Sharma <atri.jiit@gmail.com>

Author: atris

server/src/main/java/org/opensearch/action/search/StreamQueryPhaseResultConsumer.java

@@ -26,7 +26,6 @@
  * Batch reduction frequency is controlled by per-mode multipliers:
  * - NO_SCORING: Immediate reduction (batch size = 1) for fastest time-to-first-byte
  * - SCORED_UNSORTED: Small batches (minBatchReduceSize * 2)
- * - CONFIDENCE_BASED: Moderate batches (minBatchReduceSize * 3)
  * - SCORED_SORTED: Larger batches (minBatchReduceSize * 10)
  *
  * These multipliers are applied to the base batch reduce size (typically 5) to determine
@@ -97,9 +96,6 @@ int getBatchReduceSize(int requestBatchedReduceSize, int minBatchReduceSize) {
             case SCORED_UNSORTED:
                 // Small batches for quick emission without sorting overhead
                 return super.getBatchReduceSize(requestBatchedReduceSize, minBatchReduceSize * 2);
-            case CONFIDENCE_BASED:
-                // Moderate batching for progressive emission with confidence
-                return super.getBatchReduceSize(requestBatchedReduceSize, minBatchReduceSize * 3);
             case SCORED_SORTED:
                 // Higher batch size to collect more results before reducing (sorting is expensive)
                 return super.getBatchReduceSize(requestBatchedReduceSize, minBatchReduceSize * 10);

server/src/main/java/org/opensearch/action/search/StreamSearchTransportService.java

@@ -211,13 +211,7 @@ public SearchPhaseResult read(StreamInput in) throws IOException {
                 fetchDocuments
             );
         }
-        transportService.sendChildRequest(
-            connection,
-            QUERY_ACTION_NAME,
-            request,
-            task,
-            transportHandler // TODO: wrap with ConnectionCountingHandler
-        );
+        transportService.sendChildRequest(connection, QUERY_ACTION_NAME, request, task, transportHandler);
     }
 
     @Override

server/src/main/java/org/opensearch/action/search/StreamingSearchProgressListener.java

@@ -22,7 +22,7 @@
 
 /**
  * SearchProgressListener implementation for streaming search with scoring.
- * Computes partial search results when confidence thresholds are met.
+ * Computes partial search results progressively as shards complete.
  *
  * @opensearch.internal
  */

server/src/main/java/org/opensearch/action/search/StreamingSearchProgressMessage.java

@@ -59,7 +59,6 @@ public static Milestone fromProgress(float progress) {
     private final long requestId;
     private final Milestone milestone;
     private final TopDocs topDocs;
-    private final float confidence;
     private final ProgressStatistics statistics;
     private final boolean isFinal;
 
@@ -70,7 +69,6 @@ public StreamingSearchProgressMessage() {
         this.requestId = -1;
         this.milestone = Milestone.INITIAL;
         this.topDocs = null;
-        this.confidence = 0.0f;
         this.statistics = null;
         this.isFinal = false;
     }
@@ -81,7 +79,6 @@ public StreamingSearchProgressMessage(
         long requestId,
         Milestone milestone,
         TopDocs topDocs,
-        float confidence,
         ProgressStatistics statistics,
         boolean isFinal
     ) {
@@ -90,7 +87,6 @@ public StreamingSearchProgressMessage(
         this.requestId = requestId;
         this.milestone = milestone;
         this.topDocs = topDocs;
-        this.confidence = confidence;
         this.statistics = statistics;
         this.isFinal = isFinal;
     }
@@ -113,7 +109,6 @@ public StreamingSearchProgressMessage(StreamInput in) throws IOException {
         }
         this.topDocs = new TopDocs(new TotalHits(totalHits, TotalHits.Relation.EQUAL_TO), scoreDocs);
 
-        this.confidence = in.readFloat();
         this.statistics = new ProgressStatistics(in);
         this.isFinal = in.readBoolean();
     }
@@ -133,7 +128,6 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeFloat(doc.score);
         }
 
-        out.writeFloat(confidence);
         statistics.writeTo(out);
         out.writeBoolean(isFinal);
     }
@@ -158,10 +152,6 @@ public TopDocs getTopDocs() {
         return topDocs;
     }
 
-    public float getConfidence() {
-        return confidence;
-    }
-
     public ProgressStatistics getStatistics() {
         return statistics;
     }
@@ -270,7 +260,6 @@ public static class Builder {
         private long requestId;
         private Milestone milestone;
         private TopDocs topDocs;
-        private float confidence = 0.0f;
         private ProgressStatistics statistics;
         private boolean isFinal = false;
 
@@ -299,11 +288,6 @@ public Builder topDocs(TopDocs topDocs) {
             return this;
         }
 
-        public Builder confidence(float confidence) {
-            this.confidence = confidence;
-            return this;
-        }
-
         public Builder statistics(ProgressStatistics statistics) {
             this.statistics = statistics;
             return this;
@@ -315,16 +299,7 @@ public Builder isFinal(boolean isFinal) {
         }
 
         public StreamingSearchProgressMessage build() {
-            return new StreamingSearchProgressMessage(
-                shardTarget,
-                shardIndex,
-                requestId,
-                milestone,
-                topDocs,
-                confidence,
-                statistics,
-                isFinal
-            );
+            return new StreamingSearchProgressMessage(shardTarget, shardIndex, requestId, milestone, topDocs, statistics, isFinal);
         }
     }
 }