Resolve tech feedback

Signed-off-by: Junqiu Lei <[email protected]>

_field-types/supported-field-types/knn-vector.md

@@ -367,15 +367,49 @@ GET test-binary-hnsw/_search
 
 The follow example demonstrates how to create a binary vector index with the Faiss engine and IVF algorithm:
 
-Firstly, we need create the training index and model in binary format. For convenience, we use above `test-binary-hnsw` index and `my_vector1` field as the training index and field to train model.
+Firstly, we need create the training index with binary format data type:
+```json
+PUT train-index
+{
+  "mappings": {
+    "properties": {
+      "train-field": {
+        "type": "knn_vector",
+        "dimension": 8,
+        "data_type": "binary"
+      }
+    }
+  }
+}
+```
+{% include copy-curl.html %}'
+
+Then, ingest some documents with binary vectors to the training index:
+```json
+PUT _bulk
+{ "index": { "_index": "train-index", "_id": "1" } }
+{ "train-field": [1] }
+{ "index": { "_index": "train-index", "_id": "2" } }
+{ "train-field": [2] }
+{ "index": { "_index": "train-index", "_id": "3" } }
+{ "train-field": [3] }
+{ "index": { "_index": "train-index", "_id": "4" } }
+{ "train-field": [4] }
+{ "index": { "_index": "train-index", "_id": "5" } }
+{ "train-field": [5] }
+...
+```
+{% include copy-curl.html %}
+
+Then, train the model with the training index and field in binary format, and specify the method space type as `hamming`:
 
 ```json
 POST _plugins/_knn/models/test-binary-model/_train
 {
-  "training_index": "test-binary-hnsw",
-  "training_field": "my_vector",
+  "training_index": "train-index",
+  "training_field": "train-field",
   "dimension": 8,
-  "description": "My model description",
+  "description": "model with binary data",
   "data_type": "binary",
   "method": {
     "name": "ivf",
@@ -390,7 +424,13 @@ POST _plugins/_knn/models/test-binary-model/_train
 ```
 {% include copy-curl.html %}
 
-Then create IVF index with the trained model:
+Then, make sure the model state is `created`:
+```json
+GET _plugins/_knn/models/test-binary-model?filter_path=state
+```
+{% include copy-curl.html %}
+
+Then, create IVF index with the trained model:
 
 ```json
 PUT test-binary-ivf
@@ -402,7 +442,7 @@ PUT test-binary-ivf
   },
   "mappings": {
     "properties": {
-      "my_vector1": {
+      "my_vector": {
         "type": "knn_vector",
         "model_id": "test-binary-model"
       }

_search-plugins/knn/approximate-knn.md

@@ -368,7 +368,7 @@ Not every method supports each of these spaces. Be sure to check out [the method
     </td>
   </tr>
   <tr>
-    <td>hammingbit</td>
+    <td>hamming</td>
     <td>\[ d(\mathbf{x}, \mathbf{y}) = \text{countSetBits}(\mathbf{x} \oplus \mathbf{y})\]</td>
     <td>\[ score = {1 \over 1 + d } \]</td>
   </tr>
@@ -383,3 +383,6 @@ With cosine similarity, it is not valid to pass a zero vector (`[0, 0, ...]`) as
 such a vector is 0, which raises a `divide by 0` exception in the corresponding formula. Requests
 containing the zero vector will be rejected and a corresponding exception will be thrown.
 {: .note }
+
+The `hamming` space type is supported for binary format vectors only in OpenSearch 2.16 and later, see [Binary vector]({{site.url}}{{site.baseurl}}/field-types/supported-field-types/knn-vector#binary-vector).
+{: .note}

_search-plugins/knn/knn-score-script.md

@@ -323,6 +323,11 @@ A space corresponds to the function used to measure the distance between two poi
     <td>\[ d(\mathbf{x}, \mathbf{y}) = \text{countSetBits}(\mathbf{x} \oplus \mathbf{y})\]</td>
     <td>\[ score = {1 \over 1 + d } \]</td>
   </tr>
+  <tr>
+    <td>hamming</td>
+    <td>\[ d(\mathbf{x}, \mathbf{y}) = \text{countSetBits}(\mathbf{x} \oplus \mathbf{y})\]</td>
+    <td>\[ score = {1 \over 1 + d } \]</td>
+  </tr>
 </table>
 
 
@@ -331,4 +336,7 @@ Cosine similarity returns a number between -1 and 1, and because OpenSearch rele
 With cosine similarity, it is not valid to pass a zero vector (`[0, 0, ...`]) as input. This is because the magnitude of
 such a vector is 0, which raises a `divide by 0` exception in the corresponding formula. Requests 
 containing the zero vector will be rejected and a corresponding exception will be thrown.
-{: .note }
+{: .note }
+
+The `hamming` space type is supported for binary format vectors only in OpenSearch 2.16 and later, see [Binary vector]({{site.url}}{{site.baseurl}}/field-types/supported-field-types/knn-vector#binary-vector).
+{: .note}

_search-plugins/knn/painless-functions.md

@@ -54,6 +54,9 @@ l1Norm | `float l1Norm (float[] queryVector, doc['vector field'])` | This functi
 cosineSimilarity | `float cosineSimilarity (float[] queryVector, doc['vector field'])` | Cosine similarity is an inner product of the query vector and document vector normalized to both have a length of 1. If the magnitude of the query vector doesn't change throughout the query, you can pass the magnitude of the query vector to improve performance, instead of calculating the magnitude every time for every filtered document:<br /> `float cosineSimilarity (float[] queryVector, doc['vector field'], float normQueryVector)` <br />In general, the range of cosine similarity is [-1, 1]. However, in the case of information retrieval, the cosine similarity of two documents ranges from 0 to 1 because the tf-idf statistic can't be negative. Therefore, the k-NN plugin adds 1.0 in order to always yield a positive cosine similarity score.
 hamming | `float hamming (float[] queryVector, doc['vector field'])` | This function calculates the Hamming distance between a given query vector and document vectors. The Hamming distance is the number of positions at which the corresponding elements are different. The shorter the distance, the more relevant the document is, so this example inverts the return value of the Hamming distance.
 
+The `hamming` space type is supported for binary format vectors only in OpenSearch 2.16 and later, see [Binary vector]({{site.url}}{{site.baseurl}}/field-types/supported-field-types/knn-vector#binary-vector).
+{: .note}
+
 ## Constraints
 
 1. If a document’s `knn_vector` field has different dimensions than the query, the function throws an `IllegalArgumentException`.