Adding visit_percentage for the new DiskBBQ (#5495)

Author: john-wagster

specification/_types/Knn.ts

@@ -43,6 +43,11 @@ export interface KnnSearch {
   k?: integer
   /** The number of nearest neighbor candidates to consider per shard */
   num_candidates?: integer
+  /** The percentage of vectors to explore per shard while doing knn search with bbq_disk
+   * @availability stack since=9.2.0
+   * @availability serverless
+   */
+  visit_percentage?: float
   /** Boost value to apply to kNN scores */
   boost?: float
   /** Filters for the kNN search query */
@@ -73,6 +78,11 @@ export interface KnnQuery extends QueryBase {
   query_vector_builder?: QueryVectorBuilder
   /** The number of nearest neighbor candidates to consider per shard */
   num_candidates?: integer
+  /** The percentage of vectors to explore per shard while doing knn search with bbq_disk
+   * @availability stack since=9.2.0
+   * @availability serverless
+   */
+  visit_percentage?: float
   /** The final number of nearest neighbors to return as top hits */
   k?: integer
   /** Filters for the kNN search query */

specification/_types/Retriever.ts

@@ -124,6 +124,11 @@ export class KnnRetriever extends RetrieverBase {
   k: integer
   /** Number of nearest neighbor candidates to consider per shard. */
   num_candidates: integer
+  /** The percentage of vectors to explore per shard while doing knn search with bbq_disk
+   * @availability stack since=9.2.0
+   * @availability serverless
+   */
+  visit_percentage?: float
   /** The minimum similarity required for a document to be considered a match.  */
   similarity?: float
   /** Apply oversampling and rescoring to quantized vectors