Disable HNSW connectedComponents (#14214) (#14436)

* Disable HNSW connectedComponents (#14214)

* add changes

Author: benwtrent

lucene/CHANGES.txt

@@ -203,6 +203,8 @@ Bug Fixes
 
 * GITHUB#14320: Fix DirectIOIndexInput seek to not read when position is within buffer (Chris Hegarty)
 
+* GITHUB#14436: Disable connectedComponents logic in HNSW graph building. Relates to GITHUB#14214, GITHUB#12627, GITHUB#13566. (Ben Trent)
+
 Changes in Runtime Behavior
 ---------------------
 * GITHUB#14189: Bump floor segment size to 16MB in TieredMergePolicy and

lucene/core/src/java/org/apache/lucene/util/hnsw/HnswGraphBuilder.java

@@ -448,10 +448,13 @@ private static int getRandomGraphLevel(double ml, SplittableRandom random) {
 
   void finish() throws IOException {
     // System.out.println("finish " + frozen);
-    connectComponents();
+    // TODO: Connect components can be exceptionally expensive, disabling
+    //  see: https://github.com/apache/lucene/issues/14214
+    // connectComponents();
     frozen = true;
   }
 
+  @SuppressWarnings("unused")
   private void connectComponents() throws IOException {
     long start = System.nanoTime();
     for (int level = 0; level < hnsw.numLevels(); level++) {