Remove redundant merge validation

Author: kderusso

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapper.java

@@ -211,7 +211,7 @@ public static class Builder extends FieldMapper.Builder {
             mapper -> ((SemanticTextFieldType) mapper.fieldType()).indexOptions,
             XContentBuilder::field,
             Objects::toString
-        ).acceptsNull().setMergeValidator(SemanticTextFieldMapper::canMergeIndexOptions);
+        ).acceptsNull();
 
         @SuppressWarnings("unchecked")
         private final Parameter<ChunkingSettings> chunkingSettings = new Parameter<>(
@@ -293,10 +293,19 @@ protected void merge(FieldMapper mergeWith, Conflicts conflicts, MapperMergeCont
             SemanticTextFieldMapper semanticMergeWith = (SemanticTextFieldMapper) mergeWith;
             semanticMergeWith = copySettings(semanticMergeWith, mapperMergeContext);
 
-            var context = mapperMergeContext.createChildContext(semanticMergeWith.leafName(), ObjectMapper.Dynamic.FALSE);
-            var inferenceField = inferenceFieldBuilder.apply(context.getMapperBuilderContext());
-            var mergedInferenceField = inferenceField.merge(semanticMergeWith.fieldType().getInferenceField(), context);
-            inferenceFieldBuilder = c -> mergedInferenceField;
+            // We make sure to merge the inference field first to catch any model conflicts
+            try {
+                var context = mapperMergeContext.createChildContext(semanticMergeWith.leafName(), ObjectMapper.Dynamic.FALSE);
+                var inferenceField = inferenceFieldBuilder.apply(context.getMapperBuilderContext());
+                var mergedInferenceField = inferenceField.merge(semanticMergeWith.fieldType().getInferenceField(), context);
+                inferenceFieldBuilder = c -> mergedInferenceField;
+            } catch (Exception e) {
+                // Wrap errors in nicer messages that hide inference field internals
+                String errorMessage = e.getMessage() != null
+                    ? e.getMessage().replaceAll(SemanticTextField.getEmbeddingsFieldName(""), "")
+                    : "";
+                throw new IllegalArgumentException(errorMessage, e);
+            }
 
             super.merge(semanticMergeWith, conflicts, mapperMergeContext);
             conflicts.check();
@@ -1237,30 +1246,6 @@ private static boolean canMergeModelSettings(MinimalServiceSettings previous, Mi
         return false;
     }
 
-    private static boolean canMergeIndexOptions(SemanticTextIndexOptions previous, SemanticTextIndexOptions current, Conflicts conflicts) {
-        if (Objects.equals(previous, current)) {
-            return true;
-        }
-
-        if (previous == null || current == null) {
-            return true;
-        }
-
-        if (previous.type() == SemanticTextIndexOptions.SupportedIndexOptions.DENSE_VECTOR) {
-            DenseVectorFieldMapper.DenseVectorIndexOptions previousDenseOptions = (DenseVectorFieldMapper.DenseVectorIndexOptions) previous
-                .indexOptions();
-            DenseVectorFieldMapper.DenseVectorIndexOptions currentDenseOptions = (DenseVectorFieldMapper.DenseVectorIndexOptions) current
-                .indexOptions();
-            boolean updatable = previousDenseOptions.updatableTo(currentDenseOptions);
-            if (updatable == false) {
-                conflicts.addConflict(INDEX_OPTIONS_FIELD, "Incompatible index options");
-            }
-            return updatable;
-        }
-
-        return true;
-    }
-
     private static SemanticTextIndexOptions parseIndexOptionsFromMap(String fieldName, Object node, IndexVersion indexVersion) {
 
         if (node == null) {

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapperTests.java

@@ -587,14 +587,7 @@ public void testUpdateModelSettings() throws IOException {
                         )
                     )
                 );
-                assertThat(
-                    exc.getMessage(),
-                    containsString(
-                        "Cannot update parameter [model_settings] "
-                            + "from [service=null, task_type=sparse_embedding] "
-                            + "to [service=null, task_type=text_embedding, dimensions=10, similarity=cosine, element_type=float]"
-                    )
-                );
+                assertThat(exc.getMessage(), containsString("cannot be changed from type [sparse_vector] to [dense_vector]"));
             }
         }
     }

x-pack/plugin/inference/src/yamlRestTest/resources/rest-api-spec/test/inference/10_semantic_text_field_mapping.yml

@@ -27,7 +27,7 @@ setup:
             "service": "text_embedding_test_service",
             "service_settings": {
               "model": "my_model",
-              "dimensions": 10,
+              "dimensions": 4,
               "similarity": "cosine",
               "api_key": "abc64"
             },
@@ -820,7 +820,7 @@ setup:
   - match: { "test-index-options.mappings.properties.semantic_field.index_options.dense_vector.confidence_interval": 1.0 }
 
   - do:
-      catch: /Incompatible index options/
+      catch: /Cannot update parameter \[index_options\]/
       indices.put_mapping:
         index: test-index-options
         body:

x-pack/plugin/inference/src/yamlRestTest/resources/rest-api-spec/test/inference/10_semantic_text_field_mapping_bwc.yml

@@ -27,7 +27,7 @@ setup:
             "service": "text_embedding_test_service",
             "service_settings": {
               "model": "my_model",
-              "dimensions": 10,
+              "dimensions": 4,
               "similarity": "cosine",
               "api_key": "abc64"
             },
@@ -723,7 +723,7 @@ setup:
   - match: { "test-index-options.mappings.properties.semantic_field.index_options.dense_vector.confidence_interval": 1.0 }
 
   - do:
-      catch: /Incompatible index options/
+      catch: /Cannot update parameter \[index_options\]/
       indices.put_mapping:
         index: test-index-options
         body: