> ## Documentation Index
> Fetch the complete documentation index at: https://ngquct-refactor-theme-settings-panes.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# DuckDB
> Open local DuckDB files or connect to a remote DuckDB server over Quack
export const name_0 = "DuckDB"
export const plugin_0 = "DuckDB Driver"
Pick a `.duckdb` file to open a database, or a `.parquet`, `.csv`, `.tsv`, `.json` or `.ndjson` file to read it where it sits. DuckDB 1.5.2 is compiled into the driver, so nothing runs as a server unless you point the connection at one.
The {name_0} driver is not in the app. Picking {name_0} in the **Choose a Database** sheet offers the
download before the form opens, and opening a saved {name_0} connection installs it without asking.
**Settings > Plugins > Browse > {plugin_0}** installs it up front. See [Plugins](/features/plugins).
## Quick setup
Click **New Connection…** or press `Cmd+N`, then choose **DuckDB**.
Leave **Connection Type** on **Local File** and click **Browse…**. Type `:memory:` in the field instead for a database that lasts as long as the session.
Click **Save & Connect**.
## What the file field accepts
| Path | What you get |
| ---------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `.duckdb`, `.ddb` | The database in that file. A path that does not exist yet is created |
| `.parquet`, `.csv`, `.tsv`, `.json`, `.ndjson` | An in-memory database holding two read-only views over the file, one named `file` and one named after the file. A path that does not exist is reported instead of created |
| `:memory:` | An empty database, discarded on disconnect |
In Local File mode the path is the whole connection, and it is required; the form shows no host, port or Database field.
Double-click a `.duckdb` or `.ddb` file in Finder to open it here. `.parquet` files list TablePro under **Open With** rather than taking the association; to make a double-click open them here, select one in Finder, press `Cmd+I`, set **Open with** to TablePro, and click **Change All…**. `.csv`, `.tsv`, `.json` and `.ndjson` open from the connection form only.
A DuckDB database carries `DUCK` eight bytes in, so a database opens under any name: drag `warehouse.db` onto a window and it reaches this driver rather than SQLite. The data formats need their extension either way, because the reader is chosen from it. Installing the plugin is offered first when it is not already there.
## Remote (Quack)
Quack is DuckDB's client-server protocol, served by `quack_serve`. Set **Connection Type** to **Remote (Quack, experimental)**:
| Field | Value |
| ------------------ | ----------------------------------------------------------------- |
| **Host** | Server address. Required |
| **Port** | `9494` by default |
| **Token** | The token the server was started with |
| **Database Alias** | The name the remote is attached under. Pre-filled with `remotedb` |
**Save & Connect** attaches the remote to an in-memory DuckDB. Reach it through the alias: `SELECT * FROM remotedb.main.orders`.
The `quack` extension is not linked into the macOS build. DuckDB downloads it from `extensions.duckdb.org` on the first remote connect and caches it under `~/.duckdb`, so that one connect needs to reach that host.
## Connection URL
```text theme={null}
duckdb:///path/to/database.duckdb
quack://host:9494/alias
```
See [Connection URL Reference](/connections/urls) for all parameters.
## Databases and schemas
A connection opens one database named after the file: `analytics.duckdb` becomes `analytics`, schema `main`. `ATTACH` a second file and it joins the sidebar as a sibling database after a refresh:
```sql theme={null}
ATTACH 'warehouse.duckdb' AS warehouse;
```
Press `Cmd+K` to move between them, in place, with no reconnect. DuckDB does not persist attachments, so a reconnect starts again from the one file. `system` and `temp` are hidden, and with them `information_schema` and `pg_catalog`.
Any connection can also read a file straight from SQL:
```sql theme={null}
SELECT * FROM 'data.csv';
SELECT * FROM read_parquet('analytics.parquet');
```
## Sharing the file with another process
One process writes a DuckDB file at a time, and the lock lasts as long as the connection. While a tab is open on `sales.duckdb`, `duckdb sales.duckdb` in a terminal is refused, and so is a notebook, a dbt run, or a second TablePro window.
Three ways out, in **Options** on the connection:
| Setting | What happens | Pick this when |
| ------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------- |
| **Release the File Lock After** | The file is handed back once the connection has been idle that many minutes, and taken again on the next query. `0`, the default, keeps it | A script or a scheduled job needs the file while you are reading it |
| **Open the File Read-Only** | The file is opened read-only, which several processes can do at once. Writes are refused by the engine | Two or more readers, and nothing writing |
| Neither | The lock is held for the life of the connection | Nothing else touches the file |
**Database ▸ Release File Lock** hands it back now, without ending the session. The tabs, the schema cache and the row you were on all stay; the next query takes the file again.
A release is refused, with the reason, while the session holds anything reopening would destroy: an open transaction, a temporary table or view, an attached database, or a changed setting. Commit the transaction or drop the temporary table and the release goes through.
Read-only is not a way to keep writing from somewhere else. A read-write connection blocks every other process, read-only ones included; a read-only connection blocks writers. Two readers work, a reader and a writer do not.
Releasing hands the file to whoever wants it next, which may not be you. A query run after another process has taken it fails until that process lets go; reconnect once it has.
## Limitations
* A DuckDB file takes one writer at a time. A connect against a file another process holds fails, naming that process and its process ID. Quit the `duckdb` CLI, the Python process or the other TablePro window first, or set **Release the File Lock After**.
* A data file opened through **Browse…** is read-only, and the file on disk is left byte for byte identical. To change its contents, open a `.duckdb` database and run `CREATE TABLE t AS SELECT * FROM 'data.parquet'`.
* Remote (Quack) lists no tables in the sidebar. Write them out by name through the alias.
* No SSL/TLS section and no SSH tunnel. The engine is in-process; see [SSL/TLS](/connections/ssl).
* No creating or dropping a database. `ATTACH` is the way to reach a second file.
## Troubleshooting
### No file at …
A data-file path that is not there. Only `.duckdb` and `.ddb` are created on demand. Re-pick the file with **Browse…**.
### DuckDB opened the file but reported no catalog to browse
The file opened and exposed nothing to list. Check that it is a DuckDB database and not a file with a borrowed extension.
### Port must be a number between 1 and 65535
**Port** holds something else. The Quack default is `9494`.
### … is using sales.duckdb
Another process holds the file. The message names it and its process ID. Quit it, or turn on **Open the File Read-Only** when the message says read-only would get in, which it does when the other process is itself a reader.
### The database file is no longer at …
The file moved or was deleted while the connection was idle with its lock released. Point the connection at the new path, or restore the file, then reconnect.
## Related
* [TablePro for iPhone and iPad](/ios), where DuckDB opens a file picked through the Files app
* [Import & Export](/features/import-export)