From be9fa86e961e0a756630032ac01d26825914d457 Mon Sep 17 00:00:00 2001
From: weizijun <weizijun.wzj@alibaba-inc.com>
Date: Wed, 8 Jan 2025 14:35:56 +0800
Subject: [PATCH 1/2] rrf support old window_size

---
 .../search/rank/RankBuilder.java              |  2 +-
 .../rest-api-spec/test/rrf/100_rank_rrf.yml   | 34 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/server/src/main/java/org/elasticsearch/search/rank/RankBuilder.java b/server/src/main/java/org/elasticsearch/search/rank/RankBuilder.java
index 9176410f6ea35..668cc5a60ede2 100644
--- a/server/src/main/java/org/elasticsearch/search/rank/RankBuilder.java
+++ b/server/src/main/java/org/elasticsearch/search/rank/RankBuilder.java
@@ -41,7 +41,7 @@
  */
 public abstract class RankBuilder implements VersionedNamedWriteable, ToXContentObject {
 
-    public static final ParseField RANK_WINDOW_SIZE_FIELD = new ParseField("rank_window_size");
+    public static final ParseField RANK_WINDOW_SIZE_FIELD = new ParseField("rank_window_size", "window_size");
 
     public static final int DEFAULT_RANK_WINDOW_SIZE = SearchService.DEFAULT_SIZE;
 
diff --git a/x-pack/plugin/rank-rrf/src/yamlRestTest/resources/rest-api-spec/test/rrf/100_rank_rrf.yml b/x-pack/plugin/rank-rrf/src/yamlRestTest/resources/rest-api-spec/test/rrf/100_rank_rrf.yml
index 320ba70bfdae5..407238210e19c 100644
--- a/x-pack/plugin/rank-rrf/src/yamlRestTest/resources/rest-api-spec/test/rrf/100_rank_rrf.yml
+++ b/x-pack/plugin/rank-rrf/src/yamlRestTest/resources/rest-api-spec/test/rrf/100_rank_rrf.yml
@@ -104,6 +104,40 @@ setup:
   - match: { hits.hits.2.fields.text.0: "other" }
   - match: { hits.hits.2.fields.keyword.0: "other" }
 
+---
+"Simple rank with old window_size param":
+
+  - requires:
+      cluster_features: ["gte_v8.16.0"]
+      reason: "deprecation added in 8.16"
+      test_runner_features: warnings
+
+  - do:
+      warnings:
+        - "Deprecated field [rank] used, replaced by [retriever]"
+        - "Deprecated field [window_size] used, expected [rank_window_size] instead"
+      search:
+        index: test
+        body:
+          track_total_hits: false
+          fields: [ "keyword" ]
+          knn:
+            field: vector
+            query_vector: [ 0.0 ]
+            k: 3
+            num_candidates: 3
+          query:
+            term:
+              text: term
+          rank:
+            rrf:
+              window_size: 100
+              rank_constant: 1
+          size: 1
+
+  - match: { hits.hits.0._id: "1" }
+  - match: { hits.hits.0.fields.keyword.0: "other" }
+
 ---
 "Simple rank with multiple bm25 sub searches":
 

From 08b18bea2e4c7712989abe1b56431c60df58708e Mon Sep 17 00:00:00 2001
From: weizijun <weizijun.wzj@alibaba-inc.com>
Date: Wed, 8 Jan 2025 14:48:17 +0800
Subject: [PATCH 2/2] add change log

---
 docs/changelog/119724.yaml | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 docs/changelog/119724.yaml

diff --git a/docs/changelog/119724.yaml b/docs/changelog/119724.yaml
new file mode 100644
index 0000000000000..596ecc7df2500
--- /dev/null
+++ b/docs/changelog/119724.yaml
@@ -0,0 +1,5 @@
+pr: 119724
+summary: rrf support the window_size parameter to compatible with old version
+area: Search
+type: bug
+issues: []