adding check for vectors per cluster

Author: benwtrent

server/src/main/java/org/elasticsearch/index/codec/vectors/IVFVectorsFormat.java

@@ -18,7 +18,6 @@
 import org.apache.lucene.codecs.perfield.PerFieldKnnVectorsFormat;
 import org.apache.lucene.index.SegmentReadState;
 import org.apache.lucene.index.SegmentWriteState;
-import org.elasticsearch.common.util.FeatureFlag;
 
 import java.io.IOException;
 
@@ -46,7 +45,6 @@
  */
 public class IVFVectorsFormat extends KnnVectorsFormat {
 
-    static final FeatureFlag IVF_FORMAT_FEATURE_FLAG = new FeatureFlag("ivf_format");
     public static final String IVF_VECTOR_COMPONENT = "IVF";
     public static final String NAME = "IVFVectorsFormat";
     // centroid ordinals -> centroid values, offsets
@@ -69,18 +67,15 @@ public class IVFVectorsFormat extends KnnVectorsFormat {
 
     public IVFVectorsFormat(int vectorPerCluster) {
         super(NAME);
-        if (IVF_FORMAT_FEATURE_FLAG.isEnabled() == false) {
-            throw new IllegalStateException("IVF format is not enabled");
+        if (vectorPerCluster <= 0) {
+            throw new IllegalArgumentException("vectorPerCluster must be > 0");
         }
         this.vectorPerCluster = vectorPerCluster;
     }
 
     /** Constructs a format using the given graph construction parameters and scalar quantization. */
     public IVFVectorsFormat() {
         this(DEFAULT_VECTORS_PER_CLUSTER);
-        if (IVF_FORMAT_FEATURE_FLAG.isEnabled() == false) {
-            throw new IllegalStateException("IVF format is not enabled");
-        }
     }
 
     @Override

server/src/test/java/org/elasticsearch/index/codec/vectors/IVFVectorsFormatTests.java

@@ -60,7 +60,6 @@ public void testSearchWithVisitedLimit() {
 
     @Override
     protected Codec getCodec() {
-        assumeTrue("IVF format flat enabled", IVFVectorsFormat.IVF_FORMAT_FEATURE_FLAG.isEnabled());
         return TestUtil.alwaysKnnVectorsFormat(format);
     }
 }