Adding code comments

Signed-off-by: Martin Gaievski <[email protected]>
opensearch-project · Oct 24, 2022 · d015c35 · d015c35
1 parent a2b92b1
commit d015c35
Showing 1 changed file with 8 additions and 0 deletions.
diff --git a/src/main/java/org/opensearch/knn/index/query/KNNQueryBuilder.java b/src/main/java/org/opensearch/knn/index/query/KNNQueryBuilder.java
@@ -112,6 +112,8 @@ public KNNQueryBuilder(StreamInput in) throws IOException {
             fieldName = in.readString();
             vector = in.readFloatArray();
             k = in.readInt();
+            // We're checking if all cluster nodes has at least that version or higher. This check is required
+            // to avoid issues with cluster upgrade
             if (isClusterOnOrAfterMinRequiredVersion()) {
                 filter = in.readOptionalNamedWriteable(QueryBuilder.class);
             }
@@ -159,6 +161,10 @@ public static KNNQueryBuilder fromXContent(XContentParser parser) throws IOExcep
                         if (FILTER_FIELD.getPreferredName().equals(tokenName)) {
                             log.debug(String.format("Start parsing filter for field [%s]", fieldName));
                             KNNCounter.KNN_QUERY_WITH_FILTER_REQUESTS.increment();
+                            // Query filters are supported starting from a certain k-NN version only, exact version is defined by
+                            // MINIMAL_SUPPORTED_VERSION_FOR_LUCENE_HNSW_FILTER variable.
+                            // Here we're checking if all cluster nodes has at least that version or higher. This check is required
+                            // to avoid issues with rolling cluster upgrade
                             if (isClusterOnOrAfterMinRequiredVersion()) {
                                 filter = parseInnerQueryBuilder(parser);
                             } else {
@@ -204,6 +210,8 @@ protected void doWriteTo(StreamOutput out) throws IOException {
         out.writeString(fieldName);
         out.writeFloatArray(vector);
         out.writeInt(k);
+        // We're checking if all cluster nodes has at least that version or higher. This check is required
+        // to avoid issues with cluster upgrade
         if (isClusterOnOrAfterMinRequiredVersion()) {
             out.writeOptionalNamedWriteable(filter);
         }