refactor: 重构RAG核心组件，简化代码结构和测试文件

backend/rag_core/client.py

@@ -1,7 +1,12 @@
 # rag_core/client.py
 import os
-from .config import QDRANT_URL, QDRANT_API_KEY
+from .config import QDRANT_URL, QDRANT_API_KEY, DOCSTORE_URI
 from qdrant_client import QdrantClient, AsyncQdrantClient
+from typing import Tuple
+from langchain_core.stores import BaseStore
+import logging
+
+logger = logging.getLogger(__name__)
 
 
 def create_qdrant_client(timeout: int = 300) -> QdrantClient:
@@ -54,3 +59,47 @@ def create_async_qdrant_client(timeout: int = 300) -> AsyncQdrantClient:
         client_kwargs["api_key"] = QDRANT_API_KEY
 
     return AsyncQdrantClient(**client_kwargs)
+
+
+def get_docstore_uri() -> str:
+    """获取 docstore 专用的数据库连接字符串（可与主库相同）"""
+    return DOCSTORE_URI
+
+
+def create_docstore(
+    table_name: str = "parent_documents",
+    pool_config: dict | None = None,
+    max_concurrency: int | None = None
+) -> Tuple[BaseStore, str]:
+    """
+    工厂函数，创建 PostgreSQL 文档存储。
+
+    Args:
+        table_name: PostgreSQL 表名（默认：parent_documents）
+        pool_config: 连接池配置
+        max_concurrency: 最大并发操作数，如果为 None 则不限制
+
+    Returns:
+        元组 (存储实例, 连接字符串)
+
+    Raises:
+        ImportError: 缺少必要的依赖
+
+    Example:
+        >>> # 创建 PostgreSQL 存储
+        >>> store, conn = create_docstore(
+        ...     table_name="parent_docs",
+        ...     max_concurrency=10
+        ... )
+    """
+    from .doc_store import PostgresDocStore
+    
+    conn_str = get_docstore_uri()
+    store = PostgresDocStore(
+        connection_string=conn_str,
+        table_name=table_name,
+        pool_config=pool_config,
+        max_concurrency=max_concurrency
+    )
+    logger.info(f"PostgreSQL docstore 已创建: {table_name}")
+    return store, conn_str