Replace postgresql with sql in langchain

Signed-off-by: Jael Gu <mengjia.gu@zilliz.com>

README.md

@@ -159,22 +159,21 @@ The option using LangChain employs the use of [Agent](https://python.langchain.c
 
         - Vector Store: You need to prepare the service of vector database in advance. For example, you can refer to [Milvus Documents](https://milvus.io/docs) or [Zilliz Cloud](https://zilliz.com/doc/quick_start) to learn about how to start a Milvus service.
         - Scalar Store (Optional): This is optional, only work when `USE_SCALAR` is true in [configuration](config.py). If this is enabled (i.e. USE_SCALAR=True), the default scalar store will use [Elastic](https://www.elastic.co/). In this case, you need to prepare the Elasticsearch service in advance.
-        - Memory Store: You need to prepare the database for memory storage as well. By default, LangChain mode supports [Postgresql](https://www.postgresql.org/) and Towhee mode allows interaction with any database supported by [SQLAlchemy 2.0](https://docs.sqlalchemy.org/en/20/dialects/).
+        - Memory Store: You need to prepare the database for memory storage as well. By default, both LangChain and Towhee mode allow interaction with any database supported by [SQLAlchemy 2.0](https://docs.sqlalchemy.org/en/20/dialects/).
 
         The system will use default store configs.
         To set up your special connections for each database, you can also export environment variables instead of modifying the configuration file.
 
-        For the Vector Store, set **MILVUS_URI**:
+        For the Vector Store, set **ZILLIZ_URI**:
         ```shell
-        $ export MILVUS_URI=https://localhost:19530
+        $ export ZILLIZ_URI=your_zilliz_cloud_endpoint
+        $ export ZILLIZ_TOKEN=your_zilliz_cloud_api_key  # skip this if using Milvus instance
         ```
 
         For the Memory Store, set **SQL_URI**:
         ```shell
         $ export SQL_URI={database_type}://{user}:{password}@{host}/{database_name}
-        ```
-        > LangChain mode only supports [Postgresql](https://www.postgresql.org/) as database type.
-
+        ``` 
 
         <details>
         <summary>By default, scalar store (elastic) is disabled.

config.py

@@ -72,10 +72,8 @@
 # Vector db configs
 VECTORDB_CONFIG = {
     'connection_args': {
-        'uri': os.getenv('MILVUS_URI', 'http://localhost:19530'),
-        'user': os.getenv('MILVUS_USER', ''),
-        'password': os.getenv('MILVUS_PASSWORD', ''),
-        'secure': True if os.getenv('MILVUS_SECURE', 'False').lower() == 'true' else False
+        'uri': os.getenv('ZILLIZ_URI', 'http://localhost:19530'),
+        'token': os.getenv('ZILLIZ_TOKEN')
         },
     'top_k': 5,
     'threshold': 0,
@@ -104,7 +102,7 @@
 
 # Memory db configs
 MEMORYDB_CONFIG = {
-    'connect_str': os.getenv('SQL_URI', 'postgresql://postgres:postgres@localhost/chat_history')
+    'connect_str': os.getenv('SQL_URI', 'sqlite:///./sqlite.db')
 }
 
 

src_langchain/store/README.md

@@ -23,7 +23,7 @@ The default module also works with [Zilliz Cloud](https://zilliz.com) by setting
 # Vector db configs
 VECTORDB_CONFIG = {
     'connection_args': {
-        'uri': os.getenv('MILVUS_URI', 'your_endpoint'),
+        'uri': os.getenv('ZILLIZ_URI', 'your_endpoint'),
         'user': os.getenv('MILVUS_USER', 'user_name'),
         'password': os.getenv('MILVUS_PASSWORD', 'password_goes_here'),
         'secure': True

src_langchain/store/__init__.py

@@ -3,7 +3,7 @@
 from typing import Optional, List
 
 from .vector_store.milvus import VectorStore, Embeddings
-from .memory_store.pg import MemoryStore
+from .memory_store.sql import MemoryStore
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '../..'))
 

src_langchain/store/memory_store/sql.py

@@ -0,0 +1,84 @@
+import os
+import sys
+from typing import List
+
+from sqlalchemy import create_engine, inspect, MetaData, Table
+
+from langchain.schema import HumanMessage, AIMessage
+from langchain.memory import SQLChatMessageHistory, ConversationBufferMemory
+
+sys.path.append(os.path.join(os.path.dirname(__file__), '../..'))
+
+from config import MEMORYDB_CONFIG  # pylint: disable=C0413
+
+
+CONNECT_STR = MEMORYDB_CONFIG.get(
+    'connect_str', 'sqlite:///./sqlite.db')
+
+
+class MemoryStore:
+    '''Memory database APIs: add_history, get_history'''
+
+    def __init__(self, table_name: str, session_id: str):
+        '''Initialize memory storage: e.g. history_db'''
+        self.table_name = table_name
+        self.session_id = session_id
+
+        self.history_db = SQLChatMessageHistory(
+            table_name=self.table_name,
+            session_id=self.session_id,
+            connection_string=CONNECT_STR,
+        )
+        self.memory = ConversationBufferMemory(
+            memory_key='chat_history',
+            chat_memory=self.history_db,
+            return_messages=True
+        )
+
+    def add_history(self, messages: List[dict]):
+        for qa in messages:
+            if 'question' in qa:
+                self.history_db.add_user_message(qa['question'])
+            if 'answer' in qa:
+                self.history_db.add_ai_message(qa['answer'])
+
+    def get_history(self):
+        history = self.history_db.messages
+        messages = []
+        for x in history:
+            if isinstance(x, HumanMessage):
+                if len(messages) > 0 and messages[-1][0] is None:
+                    a = messages[-1][-1]
+                    del messages[-1]
+                else:
+                    a = None
+                messages.append((x.content, a))
+            if isinstance(x, AIMessage):
+                if len(messages) > 0 and messages[-1][-1] is None:
+                    q = messages[-1][0]
+                    del messages[-1]
+                else:
+                    q = None
+                messages.append((q, x.content))
+        return messages
+
+    @staticmethod
+    def drop(table_name, connect_str: str = CONNECT_STR, session_id: str = None):
+        engine = create_engine(connect_str, echo=False)
+        existence = MemoryStore.check(table_name)
+
+        if existence:
+            project_table = Table(table_name, MetaData(),
+                                  autoload_with=engine, extend_existing=True)
+            if session_id and len(session_id) > 0:
+                query = project_table.delete().where(project_table.c.session_id == session_id)
+                with engine.connect() as conn:
+                    conn.execute(query)
+                    conn.commit()
+            else:
+                query = project_table.drop(engine)
+
+    @staticmethod
+    def check(table_name, connect_str: str = CONNECT_STR):
+        engine = create_engine(connect_str, echo=False)
+        return inspect(engine).has_table(table_name)

src_langchain/store/vector_store/milvus.py

@@ -1,7 +1,8 @@
 import os
 import sys
 import logging
-from typing import Optional, Any, Tuple, List, Dict
+from typing import Optional, Any, Tuple, List, Dict, Union
+from uuid import uuid4
 
 from langchain.vectorstores import Milvus
 from langchain.embeddings.base import Embeddings
@@ -14,7 +15,7 @@
 
 logger = logging.getLogger('vector_store')
 
-CONNECTION_ARGS = VECTORDB_CONFIG.get('connection_args', {'host': 'localhost', 'port': 19530})
+CONNECTION_ARGS = VECTORDB_CONFIG.get('connection_args', {'uri': 'http://localhost:19530'})
 TOP_K = VECTORDB_CONFIG.get('top_k', 3)
 INDEX_PARAMS = VECTORDB_CONFIG.get('index_params', None)
 SEARCH_PARAMS = VECTORDB_CONFIG.get('search_params', None)
@@ -26,7 +27,12 @@ class VectorStore(Milvus):
     '''
 
     def __init__(self, table_name: str, embedding_func: Embeddings = None, connection_args: dict = CONNECTION_ARGS):
-        '''Initialize vector db'''
+        '''Initialize vector db
+        
+        connection_args:
+            uri: milvus or zilliz uri
+            token: zilliz token
+        '''
         # assert isinstance(
         #     embedding_func, Embeddings), 'Invalid embedding function. Only accept langchain.embeddings.'
         self.embedding_func = embedding_func
@@ -40,6 +46,61 @@ def __init__(self, table_name: str, embedding_func: Embeddings = None, connectio
             search_params=SEARCH_PARAMS
         )
 
+    def _create_connection_alias(self, connection_args: dict) -> str:
+        """Create the connection to the Milvus server."""
+        from pymilvus import MilvusException, connections
+
+        # Grab the connection arguments that are used for checking existing connection
+        host: str = connection_args.get('host', None)
+        port: Union[str, int] = connection_args.get('port', None)
+        uri: str = connection_args.get('uri', None)
+        user = connection_args.get('user', None)
+        password = connection_args.get('password', None)
+        token = connection_args.get('token', None)
+
+
+        _connection_args = {}
+        # Order of use is uri > host/port
+        if uri is not None:
+            _connection_args['uri'] = uri
+            given_address = uri.split('://')[1]
+        elif host is not None and port is not None:
+            _connection_args['host'] = host
+            _connection_args['port'] = port
+            given_address = f'{host}:{port}'
+        else:
+            logger.debug('Missing standard address type for reuse attempt')
+            given_address = None
+
+        # Order of use is token > user/password
+        if token is not None:
+            _connection_args['token'] = token
+            _connection_args['secure'] = True
+        elif user is not None and password is not None:
+            _connection_args['user'] = user
+            _connection_args['password'] = password
+            _connection_args['secure'] = True
+        else:
+            _connection_args['secure'] = False
+
+        # If a valid address was given, then check if a connection exists
+        if given_address is not None:
+            for con in connections.list_connections():
+                addr = connections.get_connection_addr(con[0])
+                if addr == given_address:
+                    logger.debug('Using previous connection: %s', con[0])
+                    return con[0]
+
+        # Generate a new connection if one doesn't exist
+        alias = uuid4().hex
+        try:
+            connections.connect(alias=alias, **_connection_args)
+            logger.debug('Created new connection using: %s', alias)
+            return alias
+        except MilvusException as e:
+            logger.error('Failed to create new connection using: %s', alias)
+            raise e
+
     def similarity_search_with_score_by_vector(
         self,
         embedding: List[float],