diff --git a/packages/dbgpt-app/src/dbgpt_app/scene/chat_db/auto_execute/chat.py b/packages/dbgpt-app/src/dbgpt_app/scene/chat_db/auto_execute/chat.py
index c689ede0ee..255144bdad 100644
--- a/packages/dbgpt-app/src/dbgpt_app/scene/chat_db/auto_execute/chat.py
+++ b/packages/dbgpt-app/src/dbgpt_app/scene/chat_db/auto_execute/chat.py
@@ -66,6 +66,7 @@ async def generate_input_values(self) -> Dict:
                     user_input,
                     self.curr_config.schema_retrieve_top_k,
                 )
+            logger.info(f"[RAG-NL2SQL] Retrieved table info count: {len(table_infos)}, content: {table_infos}")
         except Exception as e:
             logger.error(f"Retrieved table info error: {str(e)}")
             table_infos = await blocking_func_to_async(
diff --git a/packages/dbgpt-ext/src/dbgpt_ext/storage/vector_store/chroma_store.py b/packages/dbgpt-ext/src/dbgpt_ext/storage/vector_store/chroma_store.py
index 1c175b81bc..46b5f24b4f 100644
--- a/packages/dbgpt-ext/src/dbgpt_ext/storage/vector_store/chroma_store.py
+++ b/packages/dbgpt-ext/src/dbgpt_ext/storage/vector_store/chroma_store.py
@@ -149,11 +149,36 @@ def get_config(self) -> ChromaVectorConfig:
         return self._vector_store_config
 
     def create_collection(self, collection_name: str, **kwargs) -> Any:
-        return self._chroma_client.get_or_create_collection(
+        collection_metadata = kwargs.get("collection_metadata")
+        collection = self._chroma_client.get_or_create_collection(
             name=collection_name,
             embedding_function=None,
-            metadata=kwargs.get("collection_metadata"),
+            metadata=collection_metadata,
         )
+        # Fix: if the existing collection was created without proper distance
+        # function metadata (e.g., hnsw:space=cosine), the default L2 distance
+        # makes score = 1 - distance always negative, causing all results to be
+        # filtered out. We must delete and recreate with correct metadata.
+        if (
+            collection_metadata
+            and collection_metadata.get("hnsw:space")
+            and (
+                not collection.metadata
+                or collection.metadata.get("hnsw:space") != collection_metadata.get("hnsw:space")
+            )
+        ):
+            logger.warning(
+                f"Collection '{collection_name}' exists but has incorrect metadata "
+                f"(current: {collection.metadata}, expected: {collection_metadata}). "
+                f"Deleting and recreating with correct metadata."
+            )
+            self._chroma_client.delete_collection(collection_name)
+            collection = self._chroma_client.get_or_create_collection(
+                name=collection_name,
+                embedding_function=None,
+                metadata=collection_metadata,
+            )
+        return collection
 
     def similar_search(
         self, text, topk, filters: Optional[MetadataFilters] = None
@@ -286,7 +311,8 @@ def delete_vector_name(self, vector_name: str):
         try:
             # Check if collection exists first
             collections = self._chroma_client.list_collections()
-            collection_exists = self._collection.name in collections
+            collection_names = [c.name if hasattr(c, 'name') else str(c) for c in collections]
+            collection_exists = self._collection.name in collection_names
 
             if not collection_exists:
                 logger.warning(
@@ -295,8 +321,15 @@ def delete_vector_name(self, vector_name: str):
                 return True
 
             # Delete collection if it exists
-            self._chroma_client.delete_collection(self._collection.name)
+            deleted_name = self._collection.name
+            self._chroma_client.delete_collection(deleted_name)
             SharedSystemClient.clear_system_cache()
+            # Re-create the collection so self._collection points to a valid object
+            # Must pass collection metadata to ensure correct distance function (cosine)
+            self._collection = self._chroma_client.get_or_create_collection(
+                name=self._collection_name,
+                metadata={"hnsw:space": "cosine"},
+            )
             return True
 
         except Exception as e: