(paimon) branch master updated: [lumina] Normalize distance metric to native name in index metadata (#8676)

[lzljs3620320]

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JingsongLi pushed a commit to branch master
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The following commit(s) were added to refs/heads/master by this push:
     new d339a4d056 [lumina] Normalize distance metric to native name in index 
metadata (#8676)
d339a4d056 is described below

commit d339a4d0560ba9ff7d784962a388402d29177e2c
Author: Eunbin Son <58901024+thswls...@users.noreply.github.com>
AuthorDate: Thu Jul 16 14:17:09 2026 +0900

    [lumina] Normalize distance metric to native name in index metadata (#8676)
---
 .../lumina/index/LuminaVectorIndexOptions.java     |  3 +++
 .../lumina/index/LuminaVectorOptionsTest.java      | 31 ++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git 
a/paimon-lumina/src/main/java/org/apache/paimon/lumina/index/LuminaVectorIndexOptions.java
 
b/paimon-lumina/src/main/java/org/apache/paimon/lumina/index/LuminaVectorIndexOptions.java
index 3c067ef93b..a7e8facb18 100644
--- 
a/paimon-lumina/src/main/java/org/apache/paimon/lumina/index/LuminaVectorIndexOptions.java
+++ 
b/paimon-lumina/src/main/java/org/apache/paimon/lumina/index/LuminaVectorIndexOptions.java
@@ -125,6 +125,9 @@ public class LuminaVectorIndexOptions {
         this.indexType = options.get(INDEX_TYPE);
         validateEncodingMetricCombination(options.get(ENCODING_TYPE), 
this.metric);
         this.luminaOptions = buildLuminaOptions(options);
+        // Persist the canonical native metric name so 
LuminaIndexMeta.metric() can read it
+        // back, regardless of whether the user configured "L2" (enum) or "l2" 
(native).
+        this.luminaOptions.put(toLuminaKey(DISTANCE_METRIC), 
metric.getLuminaName());
     }
 
     /**
diff --git 
a/paimon-lumina/src/test/java/org/apache/paimon/lumina/index/LuminaVectorOptionsTest.java
 
b/paimon-lumina/src/test/java/org/apache/paimon/lumina/index/LuminaVectorOptionsTest.java
index 326b89fb9b..7403d41dd3 100644
--- 
a/paimon-lumina/src/test/java/org/apache/paimon/lumina/index/LuminaVectorOptionsTest.java
+++ 
b/paimon-lumina/src/test/java/org/apache/paimon/lumina/index/LuminaVectorOptionsTest.java
@@ -26,6 +26,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
 
 /** Tests for Lumina vector options. */
 public class LuminaVectorOptionsTest {
@@ -117,6 +118,36 @@ public class LuminaVectorOptionsTest {
         assertThat(meta.metric()).isEqualTo(LuminaVectorMetric.INNER_PRODUCT);
     }
 
+    @Test
+    public void enumFormMetricIsNormalizedToNativeNameInMeta() {
+        // A user may configure the metric using the enum-form name (e.g. 
"L2"), which
+        // parseMetric() accepts. The meta must persist the native name ("l2") 
so that the read
+        // path LuminaIndexMeta.metric() -> fromLuminaName() can resolve it 
without throwing.
+        Map<String, String> enumFormL2 = new HashMap<>();
+        enumFormL2.put("lumina.distance.metric", "L2");
+        enumFormL2.put("lumina.index.dimension", "128");
+
+        Map<String, String> l2Meta =
+                new 
LuminaVectorIndexOptions(Options.fromMap(enumFormL2)).toLuminaOptions();
+        assertThat(l2Meta).containsEntry("distance.metric", "l2");
+        assertThatCode(() -> new 
LuminaIndexMeta(l2Meta).metric()).doesNotThrowAnyException();
+        assertThat(new 
LuminaIndexMeta(l2Meta).metric()).isEqualTo(LuminaVectorMetric.L2);
+
+        // Same normalization for another enum-form metric.
+        Map<String, String> enumFormIp = new HashMap<>();
+        enumFormIp.put("lumina.distance.metric", "INNER_PRODUCT");
+        enumFormIp.put("lumina.index.dimension", "128");
+        assertThat(new 
LuminaVectorIndexOptions(Options.fromMap(enumFormIp)).toLuminaOptions())
+                .containsEntry("distance.metric", "inner_product");
+
+        // No regression: a native-form name stays as-is.
+        Map<String, String> nativeFormL2 = new HashMap<>();
+        nativeFormL2.put("lumina.distance.metric", "l2");
+        nativeFormL2.put("lumina.index.dimension", "128");
+        assertThat(new 
LuminaVectorIndexOptions(Options.fromMap(nativeFormL2)).toLuminaOptions())
+                .containsEntry("distance.metric", "l2");
+    }
+
     /** Builds the native lumina meta map (what gets serialized into the index 
file) for a field. */
     private static Map<String, String> metaFor(String fieldName, Map<String, 
String> tableOptions) {
         Options resolved =