The DuckDB driver conforms to the built-in database/sql interface.

Version 1.4.0 changed the DuckDB decimal representation from float64 to a new Decimal type, which is much more precise. If you are upgrading to v1.4.0 and are using DuckDBs decimals, please make sure to update your code to make use of the new Decimal type.

go get github.com/marcboeker/go-duckdb

go-duckdb uses CGO to make calls to DuckDB. You must build your binaries with CGO_ENABLED=1.

go-duckdb hooks into the database/sql interface provided by the Go stdlib. To open a connection, simply specify the driver type as duckdb.

db, err := sql.Open("duckdb", "")
if err != nil {
    ...
}
defer db.Close()

This creates an in-memory instance of DuckDB. To open a persistent database, you need to specify a filepath to the database file. If the file does not exist, then DuckDB creates it.

db, err := sql.Open("duckdb", "/path/to/foo.db")
if err != nil {
	...
}
defer db.Close()

If you want to set specific config options for DuckDB, you can add them as query style parameters in the form of name=value pairs to the DSN.

db, err := sql.Open("duckdb", "/path/to/foo.db?access_mode=read_only&threads=4")
if err != nil {
    ...
}
defer db.Close()

Alternatively, you can use sql.OpenDB. That way, you can perform initialization steps in a callback function before opening the database. Here's an example that installs and loads the JSON extension when opening a database with sql.OpenDB(connector).

connector, err := duckdb.NewConnector("/path/to/foo.db?access_mode=read_only&threads=4", func(execer driver.Execer) error {
    bootQueries := []string{
        "INSTALL 'json'",
        "LOAD 'json'",
    }

    for _, query := range bootQueries {
        _, err = execer.Exec(query, nil)
        if err != nil {
            ...
        }
    }
    return nil
})
if err != nil {
    ...
}

db := sql.OpenDB(connector)
defer db.Close()

Please refer to the database/sql documentation for further usage instructions.

DuckDB lives in-process. Therefore, all its memory lives in the driver. All allocations live in the host process, which is the Go application. Especially for long-running applications, it is crucial to call the corresponding Close-functions as specified in database/sql. The following is a list of examples.

db, err := sql.Open("duckdb", "")
defer db.Close()

conn, err := db.Conn(context.Background())
defer conn.Close()

rows, err := conn.QueryContext(context.Background(), "SELECT 42")
// alternatively, rows.Next() has to return false
rows.Close()

appender, err := NewAppenderFromConn(conn, "", "test")
defer appender.Close()

// if not passed to sql.OpenDB
connector, err := NewConnector("", nil)
defer connector.Close()

If you want to use the DuckDB Appender API, you can obtain a new Appender by passing a DuckDB connection to NewAppenderFromConn().

connector, err := duckdb.NewConnector("test.db", nil)
if err != nil {
	...
}
defer connector.Close()

conn, err := connector.Connect(context.Background())
if err != nil {
	...
}
defer conn.Close()

// obtain an appender from the connection
// NOTE: the table 'test_tbl' must exist in test.db
appender, err := NewAppenderFromConn(conn, "", "test_tbl")
if err != nil {
	...
}
defer appender.Close()

err = appender.AppendRow(...)
if err != nil {
	...
}

If you want to use the DuckDB Arrow Interface, you can obtain a new Arrow by passing a DuckDB connection to NewArrowFromConn().

connector, err := duckdb.NewConnector("", nil)
if err != nil {
	...
}
defer connector.Close()

conn, err := connector.Connect(context.Background())
if err != nil {
	...
}
defer conn.Close()

// obtain the Arrow from the connection
arrow, err := duckdb.NewArrowFromConn(conn)
if err != nil w
	...
}

rdr, err := arrow.QueryContext(context.Background(), "SELECT * FROM generate_series(1, 10)")
if err != nil {
	...
}
defer rdr.Release()

for rdr.Next() {
  // process records
}

By default, go-duckdb statically links DuckDB into your binary. Statically linking DuckDB adds around 30 MB to your binary size. On Linux (Intel) and macOS (Intel and ARM), go-duckdb bundles pre-compiled static libraries for fast builds.

Alternatively, you can dynamically link DuckDB by passing -tags=duckdb_use_lib to go build. You must have a copy of libduckdb available on your system (.so on Linux or .dylib on macOS), which you can download from the DuckDB releases page. For example:

# On Linux
CGO_ENABLED=1 CGO_LDFLAGS="-L/path/to/libs" go build -tags=duckdb_use_lib main.go
LD_LIBRARY_PATH=/path/to/libs ./main

# On macOS
CGO_ENABLED=1 CGO_LDFLAGS="-L/path/to/libs" go build -tags=duckdb_use_lib main.go
DYLD_LIBRARY_PATH=/path/to/libs ./main