Memory management options

Langflow provides flexible memory management options for storage and retrieval.

This page details the following memory configuration options in Langflow.

• Use local Langflow database tables
• Store messages in local memory
• Configure external memory
• Configure the external database connection
• Configure cache memory

Local Langflow database tables

The default storage option in Langflow is a SQLite database stored in your system's cache directory:

• Linux/WSL: ~/.cache/langflow/langflow.db
• macOS: /Users/<username>/Library/Caches/langflow/langflow.db
• Windows: %LOCALAPPDATA%\langflow\langflow\Cache\langflow.db

The following tables are stored in langflow.db:

• User - Stores user account information including credentials, permissions, and profiles. For more information, see Authentication.

• Flow - Contains flow configurations. For more information, see Flows.

• Message - Stores chat messages and interactions that occur between components. For more information, see Message objects.

• Transaction - Records execution history and results of flow runs. This information is used for logging.

• ApiKey - Manages API authentication keys for users. For more information, see API keys.

• Folder - Provides a structure for flow storage. For more information, see Projects and folders.

• Variables - Stores global encrypted values and credentials. For more information, see Global variables.

• VertexBuild - Tracks the build status of individual nodes within flows. For more information, see Run a flow in the playground.

For more information, see the database models in the source code.

Store messages in local memory

To store messages in local Langflow memory, add a Message store component to your flow.

To retrieve messages from local Langflow memory, add a Message history component to your flow.

For an example of using local chat memory, see the Memory chatbot starter flow.

To store or retrieve chat messages from external memory, connect the External memory port of the Message store or Message history component to a Memory component, like the Astra DB chat memory component. An example flow looks like this:

If external storage is connected to a memory helper component, no chat messages are stored in local Langflow memory.

Configure external memory

To replace the default Langflow SQLite database with another database, modify the LANGFLOW_DATABASE_URL and start Langflow with this value.

_10

LANGFLOW_DATABASE_URL=postgresql://user:password@localhost:5432/langflow

For an example, see Configure an external PostgreSQL database.

Configure the external database connection

The following settings allow you to fine-tune your database connection pool and timeout settings:

_10

LANGFLOW_DB_CONNECTION_SETTINGS='{"pool_size": 20, "max_overflow": 30, "pool_timeout": 30, "pool_pre_ping": true, "pool_recycle": 1800, "echo": false}'

_10

LANGFLOW_DB_CONNECT_TIMEOUT=20

• pool_size: Maximum number of database connections to keep in the pool (default: 20)
• max_overflow: Maximum number of connections that can be created beyond the pool_size (default: 30)
• pool_timeout: Number of seconds to wait before timing out on getting a connection from the pool (default: 30)
• pool_pre_ping: If true, the pool tests connections for liveness upon each checkout (default: true)
• pool_recycle: Number of seconds after which a connection is automatically recycled (default: 1800, or 30 minutes)
• echo: If true, SQL queries are logged for debugging purposes (default: false)
• LANGFLOW_DB_CONNECT_TIMEOUT: Maximum number of seconds to wait when establishing a new database connection (default: 20)

Configure cache memory

Langflow provides multiple caching options that can be configured using the LANGFLOW_CACHE_TYPE environment variable.

Type	Description	Storage Location	Persistence
async (default)	Asynchronous in-memory cache	Application memory	Cleared on restart
memory	Thread-safe in-memory cache	Application memory	Cleared on restart
disk	File system-based cache	System cache directory*	Persists after restart
redis	Distributed cache	Redis server	Persists in Redis

*System cache directory locations:

• Linux/WSL: ~/.cache/langflow/
• macOS: /Users/<username>/Library/Caches/langflow/
• Windows: %LOCALAPPDATA%\langflow\langflow\Cache