Connection String Parameters
To connect to a DuckDB database, a connection string should be specified. The connection string contains information about the target database and other parameters that control different aspects of the database behavior.
Basic connection
DuckDB.NET connection strings follow the standard ADO.NET syntax as a semicolon-separated list of keywords and values. The connection string must specify the database path to the database file with either DataSource or Data Source keyword. If the specified file does not exist, it will be created the first time the connection is opened.
In-Memory database
For an in-memory database use Data Source=:memory: connection string. When using an in-memory database no data is persisted on disk. Every in-memory connection results in a new, isolated database so tables created inside one in-memory connection aren't visible to another in-memory connection. If you want to create a shared in-memory database, you can use the Data Source=:memory:?cache=shared connection string. Both connection strings are exposed by the library as DuckDBConnectionStringBuilder.InMemoryDataSource and DuckDBConnectionStringBuilder.InMemorySharedDataSource respectively.
DuckDB configuration
DuckDB has several configuration options that can be used to change the behavior of the system. These options can be included in the connection string and they will be automatically set when a connection is opened.
Example connections strings
| Connection String | Description |
|---|---|
| DataSource = :memory: | Connect to a new in-memory database |
| DataSource = :memory:?cache=shared | Connect to a shared, in-memory database |
| DataSource = train_services.db | Connect to train_services.db |
| DataSource = train_services.db;ACCESS_MODE=READ_ONLY | Connect to train_services.db, make connection read-only |
| DataSource = :memory:;threads=8;ACCESS_MODE=READ_ONLY | Connect to a new in-memory database, limit threads to 8, make connection read-only |
| DataSource = train_services.db;ACCESS_MODE=READ_ONLY;memory_limit=10GB | Connect to train_services.db, make connection read-only, limit RAM usage to 10GB |