Add ignore_unmapped support in KNNQueryBuilder

CHANGELOG.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ## [Unreleased 2.x](https://github.com/opensearch-project/k-NN/compare/2.10...2.x)
 ### Features
 ### Enhancements
+* Added support for ignore_unmapped in KNN queries. [#1071](https://github.com/opensearch-project/k-NN/pull/1071)
 ### Bug Fixes 
 ### Infrastructure
 ### Documentation

src/main/java/org/opensearch/knn/index/query/KNNQueryBuilder.java

@@ -6,6 +6,7 @@
 package org.opensearch.knn.index.query;
 
 import lombok.extern.log4j.Log4j2;
+import org.apache.lucene.search.MatchNoDocsQuery;
 import org.opensearch.core.common.Strings;
 import org.opensearch.index.mapper.NumberFieldMapper;
 import org.opensearch.index.query.QueryBuilder;
@@ -43,6 +44,7 @@
     public static final ParseField VECTOR_FIELD = new ParseField("vector");
     public static final ParseField K_FIELD = new ParseField("k");
     public static final ParseField FILTER_FIELD = new ParseField("filter");
+    public static final ParseField IGNORE_UNMAPPED_FIELD = new ParseField("ignore_unmapped");
     public static int K_MAX = 10000;
     /**
      * The name for the knn query
@@ -55,6 +57,7 @@
     private final float[] vector;
     private int k = 0;
     private QueryBuilder filter;
+    private boolean ignoreUnmapped = false;
 
     /**
      * Constructs a new knn query
@@ -88,6 +91,7 @@
         this.vector = vector;
         this.k = k;
         this.filter = filter;
+        this.ignoreUnmapped = false;
     }
 
     public static void initialize(ModelDao modelDao) {
@@ -113,6 +117,7 @@
             vector = in.readFloatArray();
             k = in.readInt();
             filter = in.readOptionalNamedWriteable(QueryBuilder.class);
+            ignoreUnmapped = in.readOptionalBoolean();
         } catch (IOException ex) {
             throw new RuntimeException("[KNN] Unable to create KNNQueryBuilder", ex);
         }
@@ -126,6 +131,7 @@
         QueryBuilder filter = null;
         String queryName = null;
         String currentFieldName = null;
+        boolean ignoreUnmapped = false;
         XContentParser.Token token;
         KNNCounter.KNN_QUERY_REQUESTS.increment();
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
@@ -144,6 +150,8 @@
                             boost = parser.floatValue();
                         } else if (K_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                             k = (Integer) NumberFieldMapper.NumberType.INTEGER.parse(parser.objectBytes(), false);
+                        } else if (IGNORE_UNMAPPED_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
+                            ignoreUnmapped = parser.booleanValue();
                         } else if (AbstractQueryBuilder.NAME_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                             queryName = parser.text();
                         } else {
@@ -176,6 +184,7 @@
         }
 
         KNNQueryBuilder knnQueryBuilder = new KNNQueryBuilder(fieldName, ObjectsToFloats(vector), k, filter);
+        knnQueryBuilder.ignoreUnmapped(ignoreUnmapped);
         knnQueryBuilder.queryName(queryName);
         knnQueryBuilder.boost(boost);
         return knnQueryBuilder;
@@ -187,6 +196,7 @@
         out.writeFloatArray(vector);
         out.writeInt(k);
         out.writeOptionalNamedWriteable(filter);
+        out.writeBoolean(ignoreUnmapped);
     }
 
     /**
@@ -211,6 +221,20 @@
         return this.filter;
     }
 
+    /**
+     * Sets whether the query builder should ignore unmapped paths (and run a
+     * {@link MatchNoDocsQuery} in place of this query) or throw an exception if
+     * the path is unmapped.
+     */
+    public KNNQueryBuilder ignoreUnmapped(boolean ignoreUnmapped) {
+        this.ignoreUnmapped = ignoreUnmapped;
+        return this;
+    }
+
+    public boolean getIgnoreUnmapped() {
+        return this.ignoreUnmapped;
+    }
+
     @Override
     public void doXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject(NAME);
@@ -221,6 +245,7 @@
         if (filter != null) {
             builder.field(FILTER_FIELD.getPreferredName(), filter);
         }
+        builder.field(IGNORE_UNMAPPED_FIELD.getPreferredName(), ignoreUnmapped);
         printBoostAndQueryName(builder);
         builder.endObject();
         builder.endObject();
@@ -230,6 +255,10 @@
     protected Query doToQuery(QueryShardContext context) {
         MappedFieldType mappedFieldType = context.fieldMapper(this.fieldName);
 
+        if (mappedFieldType == null && ignoreUnmapped) {
+            return new MatchNoDocsQuery();
+        }
+
         if (!(mappedFieldType instanceof KNNVectorFieldMapper.KNNVectorFieldType)) {
             throw new IllegalArgumentException(String.format("Field '%s' is not knn_vector type.", this.fieldName));
         }

src/test/java/org/opensearch/knn/index/query/KNNQueryBuilderTests.java

@@ -7,6 +7,7 @@
 
 import com.google.common.collect.ImmutableMap;
 import org.apache.lucene.search.KnnFloatVectorQuery;
+import org.apache.lucene.search.MatchNoDocsQuery;
 import org.apache.lucene.search.Query;
 import org.opensearch.Version;
 import org.opensearch.cluster.ClusterModule;
@@ -41,6 +42,7 @@
 import java.util.List;
 import java.util.Optional;
 
+import static org.hamcrest.Matchers.instanceOf;
 import static org.mockito.Mockito.anyString;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -307,4 +309,13 @@ private void assertSerialization(final Version version, final Optional<QueryBuil
             }
         }
     }
+
+    public void testIgnoreUnmapped() throws IOException {
+        float[] queryVector = { 1.0f, 2.0f, 3.0f, 4.0f };
+        KNNQueryBuilder knnQueryBuilder = new KNNQueryBuilder(FIELD_NAME, queryVector, K);
+        knnQueryBuilder.ignoreUnmapped(true);
+        Query query = knnQueryBuilder.doToQuery(mock(QueryShardContext.class));
+        assertNotNull(query);
+        assertThat(query, instanceOf(MatchNoDocsQuery.class));
+    }
 }