From f170bdd912ed2212860201b05ad720fd9bad33fd Mon Sep 17 00:00:00 2001
From: Jim Ferenczi <jim.ferenczi@elastic.co>
Date: Wed, 4 Dec 2024 08:50:08 +0000
Subject: [PATCH] address review comments

---
 .../reference/mapping/types/sparse-vector.asciidoc | 14 +++++++++-----
 .../elasticsearch/index/mapper/MapperFeatures.java |  4 +---
 .../mapper/vectors/SparseVectorFieldMapper.java    |  3 +++
 .../elasticsearch/xpack/core/XPackFeatures.java    |  6 ++++++
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/docs/reference/mapping/types/sparse-vector.asciidoc b/docs/reference/mapping/types/sparse-vector.asciidoc
index c90ed4d3515e5..22d4644ede490 100644
--- a/docs/reference/mapping/types/sparse-vector.asciidoc
+++ b/docs/reference/mapping/types/sparse-vector.asciidoc
@@ -33,11 +33,15 @@ The following parameters are accepted by `sparse_vector` fields:
 
 [horizontal]
 
-<<mapping-store,`store`>>::
-
-    Whether the field value should be stored and retrievable separately from
-    the <<mapping-source-field,`_source`>> field. Accepts `true` or `false`
-    (default).
+<<mapping-store,store>>::
+
+Indicates whether the field value should be stored and retrievable independently of the <<mapping-source-field,_source>> field.
+Accepted values: true or false (default).
+The field's data is stored using term vectors, a disk-efficient structure compared to the original JSON input.
+The input map can be retrieved during a search request via the <<search-fields-param,`fields` parameter>>.
+To benefit from reduced disk usage, you must either:
+  * Exclude the field from <<source-filtering, _source>>.
+  * Use <<synthetic-source,synthetic `_source`>>.
 
 [[index-multi-value-sparse-vectors]]
 ==== Multi-value sparse vectors
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/MapperFeatures.java b/server/src/main/java/org/elasticsearch/index/mapper/MapperFeatures.java
index 2695dd88d8571..ffb38d229078e 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/MapperFeatures.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/MapperFeatures.java
@@ -25,7 +25,6 @@ public class MapperFeatures implements FeatureSpecification {
     // Used to avoid noise in mixed cluster and rest compatibility tests. Must not be backported to 8.x branch.
     // This label gets added to tests with such failures before merging with main, then removed when backported to 8.x.
     public static final NodeFeature BWC_WORKAROUND_9_0 = new NodeFeature("mapper.bwc_workaround_9_0");
-    public static final NodeFeature SPARSE_VECTOR_STORE_SUPPORT = new NodeFeature("mapper.sparse_vector.store_support");
 
     @Override
     public Set<NodeFeature> getFeatures() {
@@ -76,8 +75,7 @@ public Set<NodeFeature> getTestFeatures() {
             MapperService.LOGSDB_DEFAULT_IGNORE_DYNAMIC_BEYOND_LIMIT,
             DocumentParser.FIX_PARSING_SUBOBJECTS_FALSE_DYNAMIC_FALSE,
             CONSTANT_KEYWORD_SYNTHETIC_SOURCE_WRITE_FIX,
-            META_FETCH_FIELDS_ERROR_CODE_CHANGED,
-            SPARSE_VECTOR_STORE_SUPPORT
+            META_FETCH_FIELDS_ERROR_CODE_CHANGED
         );
     }
 }
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/vectors/SparseVectorFieldMapper.java b/server/src/main/java/org/elasticsearch/index/mapper/vectors/SparseVectorFieldMapper.java
index 552e66336005d..0c92c9610a686 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/vectors/SparseVectorFieldMapper.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/vectors/SparseVectorFieldMapper.java
@@ -22,6 +22,7 @@
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.logging.DeprecationCategory;
 import org.elasticsearch.common.lucene.Lucene;
+import org.elasticsearch.features.NodeFeature;
 import org.elasticsearch.index.IndexVersion;
 import org.elasticsearch.index.IndexVersions;
 import org.elasticsearch.index.analysis.NamedAnalyzer;
@@ -58,6 +59,8 @@ public class SparseVectorFieldMapper extends FieldMapper {
 
     public static final String CONTENT_TYPE = "sparse_vector";
 
+    public static final NodeFeature SPARSE_VECTOR_STORE_SUPPORT = new NodeFeature("mapper.sparse_vector.store_support");
+
     static final String ERROR_MESSAGE_7X = "[sparse_vector] field type in old 7.x indices is allowed to "
         + "contain [sparse_vector] fields, but they cannot be indexed or searched.";
     static final String ERROR_MESSAGE_8X = "The [sparse_vector] field type is not supported on indices created on versions 8.0 to 8.10.";
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/XPackFeatures.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/XPackFeatures.java
index f966bf97f4764..336713f6612ff 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/XPackFeatures.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/XPackFeatures.java
@@ -9,6 +9,7 @@
 
 import org.elasticsearch.features.FeatureSpecification;
 import org.elasticsearch.features.NodeFeature;
+import org.elasticsearch.index.mapper.vectors.SparseVectorFieldMapper;
 import org.elasticsearch.license.License;
 import org.elasticsearch.xpack.core.datatiers.NodesDataTiersUsageTransportAction;
 
@@ -30,4 +31,9 @@ public Set<NodeFeature> getFeatures() {
             LOGSDB_TELMETRY_STATS
         );
     }
+
+    @Override
+    public Set<NodeFeature> getTestFeatures() {
+        return Set.of(SparseVectorFieldMapper.SPARSE_VECTOR_STORE_SUPPORT);
+    }
 }