Databricks SQL Driver for Go
November 14, 2024
The Databricks SQL Driver for Go is a Go library that allows you to use Go code to run SQL commands on Databricks compute resources. This article supplements the Databricks SQL Driver for Go README, API reference, and examples.
Requirements
A development machine running Go, version 1.20 or above. To print the installed version of Go, run the command
go version
. Download and install Go.An existing cluster or SQL warehouse.
The Server Hostname, Port, and HTTP Path values for the existing cluster or SQL warehouse.
Getting started with the Databricks SQL Driver for Go
On your development machine with Go 1.20 or above already installed and an existing Go code project already created, create a
go.mod
file to track your Go code’s dependencies by running thego mod init
command, for example:Bashgo mod init sample
Take a dependency on the Databricks SQL Driver for Go package by running the
go mod edit -require
command, replacingv1.5.2
with the latest version of the Databricks SQL Driver for Go package as listed in the Releases:Bashgo mod edit -require github.com/databricks/databricks-sql-go@v1.5.2
Your
go.mod
file should now look like this:Gomodule sample go 1.20 require github.com/databricks/databricks-sql-go v1.5.2
In your project, create a Go code file that imports the Databricks SQL Driver for Go. The following example, in a file named
main.go
with the following contents, lists all the clusters in your Databricks workspace:Gopackage main import ( "database/sql" "os" _ "github.com/databricks/databricks-sql-go" ) func main() { dsn := os.Getenv("DATABRICKS_DSN") if dsn == "" { panic("No connection string found. " + "Set the DATABRICKS_DSN environment variable, and try again.") } db, err := sql.Open("databricks", dsn) if err != nil { panic(err) } defer db.Close() if err := db.Ping(); err != nil { panic(err) } }
Add any missing module dependencies by running the
go mod tidy
command:Bashgo mod tidy
Note
If you get the error
go: warning: "all" matched no packages
, you forgot to add a Go code file that imports the Databricks SQL Driver for Go.Make copies of all packages needed to support builds and tests of packages in your
main
module, by running thego mod vendor
command:Bashgo mod vendor
Modify your code as needed to set the
DATABRICKS_DSN
environment variable for Databricks authentication. See also Connect with a DSN connection string.Run your Go code file, assuming a file named
main.go
, by running thego run
command:Bashgo run main.go
If no errors are returned, you have successfully authenticated the Databricks SQL Driver for Go with your Databricks workspace and connected to your running Databricks cluster or SQL warehouse in that workspace.
Connect with a DSN connection string
To access clusters and SQL warehouses, use sql.Open()
to create a database handle through a data source name (DSN) connection string. This code example retrieves the DSN connection string from an environment variable named DATABRICKS_DSN
:
package main
import (
"database/sql"
"os"
_ "github.com/databricks/databricks-sql-go"
)
func main() {
dsn := os.Getenv("DATABRICKS_DSN")
if dsn == "" {
panic("No connection string found. " +
"Set the DATABRICKS_DSN environment variable, and try again.")
}
db, err := sql.Open("databricks", dsn)
if err != nil {
panic(err)
}
defer db.Close()
if err := db.Ping(); err != nil {
panic(err)
}
}
To specify the DSN connection string in the correct format, see the DSN connection string examples in Authentication. For example, for Databricks personal access token authentication, use the following syntax, where:
<personal-access-token>
is your Databricks personal access token from the requirements.<server-hostname>
is the Server Hostname value from the requirements.<port-number>
is the Port value from the requirements, which is typically443
.<http-path>
is the HTTP Path value from the requirements.<paramX=valueX>
is one or more Optional parameters listed later in this article.
token:<personal-access-token>@<server-hostname>:<port-number>/<http-path>?<param1=value1>&<param2=value2>
For example, for a cluster:
token:dapi12345678901234567890123456789012@dbc-a1b2345c-d6e7.cloud.databricks.com:443/sql/protocolv1/o/1234567890123456/1234-567890-abcdefgh
For example, for a SQL warehouse:
token:dapi12345678901234567890123456789012@dbc-a1b2345c-d6e7.cloud.databricks.com:443/sql/1.0/endpoints/a1b234c5678901d2
Note
As a security best practice, you should not hard-code this DSN connection string into your Go code. Instead, you should retrieve this DSN connection string from a secure location. For example, the code example earlier in this article used an environment variable.
Optional parameters
Supported optional connection parameters can be specified in
<param=value>
. Some of the more frequently used ones include:catalog
: Sets the initial catalog name in the session.schema
: Sets the initial schema name in the session.maxRows
: Sets up the maximum number of rows fetched per request. The default is10000
.timeout
: Adds the timeout (in seconds) for the server query execution. The default is no timeout.userAgentEntry
: Used to identify partners. For more information, see your partner’s documentation.
Supported optional session parameters can be specified in
param=value
. Some of the more frequently used ones include:ansi_mode
: A Boolean string.true
for session statements to adhere to rules specified by the ANSI SQL specification. The system default is false.timezone
: A string, for exampleAmerica/Los_Angeles
. Sets the timezone of the session. The system default is UTC.
For example, for a SQL warehouse:
token:dapi12345678901234567890123456789012@dbc-a1b2345c-d6e7.cloud.databricks.com:443/sql/1.0/endpoints/a1b234c5678901d2?catalog=hive_metastore&schema=example&maxRows=100&timeout=60&timezone=America/Sao_Paulo&ansi_mode=true
Connect with the NewConnector
function
Alternatively, use sql.OpenDB()
to create a database handle through a new connector object that is created with dbsql.NewConnector()
(connecting to Databricks clusters and SQL warehouses with a new connector object requires v1.0.0 or higher of the Databricks SQL Driver for Go). For example:
package main
import (
"database/sql"
"os"
dbsql "github.com/databricks/databricks-sql-go"
)
func main() {
connector, err := dbsql.NewConnector(
dbsql.WithAccessToken(os.Getenv("DATABRICKS_ACCESS_TOKEN")),
dbsql.WithServerHostname(os.Getenv("DATABRICKS_HOST")),
dbsql.WithPort(443),
dbsql.WithHTTPPath(os.Getenv("DATABRICKS_HTTP_PATH")),
)
if err != nil {
panic(err)
}
db := sql.OpenDB(connector)
defer db.Close()
if err := db.Ping(); err != nil {
panic(err)
}
}
To specify the correct set of NewConnector
settings, see the examples in Authentication.
Note
As a security best practice, you should not hard-code your NewConnector
settings into your Go code. Instead, you should retrieve these values from a secure location. For example, the preceding code uses environment variables.
Some of the more frequently used functional options include:
WithAccessToken(<access-token>)
: Your Databricks personal access token from the requirements. Requiredstring
.WithServerHostname(<server-hostname>)
: The Server Hostname value from the requirements. Requiredstring
.WithPort(<port>)
: The server’s port number, typically443
. Requiredint
.WithHTTPPath(<http-path>)
: The HTTP Path value from the requirements. Requiredstring
.WithInitialNamespace(<catalog>, <schema>)
:The catalog and schema name in the session. Optionalstring, string
.WithMaxRows(<max-rows>)
: The maximum number of rows fetched per request. The default is10000.
Optionalint
.WithSessionParams(<params-map>)
: The session parameters including “timezone” and “ansi_mode”. Optionalmap[string]string
.WithTimeout(<timeout>)
. The timeout (intime.Duration
) for the server query execution. The default is no timeout. Optional.WithUserAgentEntry(<isv-name-plus-product-name>)
. Used to identify partners. For more information, see your partner’s documentation. Optionalstring
.
For example:
connector, err := dbsql.NewConnector(
dbsql.WithAccessToken(os.Getenv("DATABRICKS_ACCESS_TOKEN")),
dbsql.WithServerHostname(os.Getenv("DATABRICKS_HOST")),
dbsql.WithPort(443),
dbsql.WithHTTPPath(os.Getenv("DATABRICKS_HTTP_PATH")),
dbsql.WithInitialNamespace("samples", "nyctaxi"),
dbsql.WithMaxRows(100),
dbsql.SessionParams(map[string]string{"timezone": "America/Sao_Paulo", "ansi_mode": "true"}),
dbsql.WithTimeout(time.Minute),
dbsql.WithUserAgentEntry("example-user"),
)
Authentication
The Databricks SQL Driver for Go supports the following Databricks authentication types:
Databricks personal access token authentication
To use the Databricks SQL Driver for Go with Databricks personal access token authentication, you must first create a Databricks personal access token. For details on this step, see Databricks personal access tokens for workspace users.
To authenticate the Databricks SQL Driver for Go with a DSN connection string and the code example in Connect with a DSN connection string, use the following DSN connection string syntax, where:
<personal-access-token>
is your Databricks personal access token from the requirements.<server-hostname>
is the Server Hostname value from the requirements.<port-number>
is the Port value from the requirements, which is typically443
.<http-path>
is the HTTP Path value from the requirements.
You can also append one or more Optional parameters listed previously in this article.
token:<personal-access-token>@<server-hostname>:<port-number>/<http-path>
To authenticate the Databricks SQL Driver for Go with the NewConnector
function, use the following code snippet and the code example in Connect with the NewConnector function, which assumes that you have set the following environment variables:
DATABRICKS_SERVER_HOSTNAME
set to the Server Hostname value for your cluster or SQL warehouse.DATABRICKS_HTTP_PATH
, set to HTTP Path value for your cluster or SQL warehouse.DATABRICKS_TOKEN
, set to the Databricks personal access token.
To set environment variables, see your operating system’s documentation.
connector, err := dbsql.NewConnector(
dbsql.WithServerHostname(os.Getenv("DATABRICKS_SERVER_HOSTNAME")),
dbsql.WithHTTPPath(os.Getenv("DATABRICKS_HTTP_PATH")),
dbsql.WithPort(443),
dbsql.WithAccessToken(os.Getenv("DATABRICKS_TOKEN")),
)
OAuth user-to-machine (U2M) authentication
Databricks SQL Driver for Go versions 1.5.0 and above support OAuth user-to-machine (U2M) authentication.
To use the Databricks SQL Driver for Go with a DSN connection string and the code example in Connect with a DSN connection string, use the following DSN connection string syntax, where:
<server-hostname>
is the Server Hostname value from the requirements.<port-number>
is the Port value from the requirements, which is typically443
.<http-path>
is the HTTP Path value from the requirements.
You can also append one or more Optional parameters listed previously in this article.
<server-hostname>:<port-number>/<http-path>?authType=OauthU2M
To authenticate the Databricks SQL Driver for Go with the NewConnector
function, you must first add the following to your import
declaration:
"github.com/databricks/databricks-sql-go/auth/oauth/u2m"
Then use the following code snippet and the code example in Connect with the NewConnector function, which assumes that you have set the following environment variables:
DATABRICKS_SERVER_HOSTNAME
set to the Server Hostname value for your cluster or SQL warehouse.DATABRICKS_HTTP_PATH
, set to HTTP Path value for your cluster or SQL warehouse.
To set environment variables, see your operating system’s documentation.
authenticator, err := u2m.NewAuthenticator(os.Getenv("DATABRICKS_SERVER_HOSTNAME"), 1*time.Minute)
if err != nil {
panic(err)
}
connector, err := dbsql.NewConnector(
dbsql.WithServerHostname(os.Getenv("DATABRICKS_SERVER_HOSTNAME")),
dbsql.WithHTTPPath(os.Getenv("DATABRICKS_HTTP_PATH")),
dbsql.WithPort(443),
dbsql.WithAuthenticator(authenticator),
)
OAuth machine-to-machine (M2M) authentication
Databricks SQL Driver for Go versions 1.5.2 and above support OAuth machine-to-machine (M2M) authentication.
To use the Databricks SQL Driver for Go with OAuth M2M authentication, you must do the following:
Create a Databricks service principal in your Databricks workspace, and create an OAuth secret for that service principal.
To create the service principal and its OAuth secret, see Authenticate access to Databricks with a service principal using OAuth (OAuth M2M). Make a note of the service principal’s UUID or Application ID value, and the Secret value for the service principal’s OAuth secret.
Give that service principal access to your cluster or warehouse.
To give the service principal access to your cluster or warehouse, see Compute permissions or Manage a SQL warehouse.
To authenticate the Databricks SQL Driver for Go with a DSN connection string and the code example in Connect with a DSN connection string, use the following DSN connection string syntax, where:
<server-hostname>
is the Server Hostname value from the requirements.<port-number>
is the Port value from the requirements, which is typically443
.<http-path>
is the HTTP Path value from the requirements.<client-id>
is the service principal’s UUID or Application ID value.<client-secret>
is the Secret value for the service principal’s OAuth secret.
You can also append one or more Optional parameters listed previously in this article.
<server-hostname>:<port-number>/<http-path>?authType=OAuthM2M&clientID=<client-id>&clientSecret=<client-secret>
To authenticate the Databricks SQL Driver for Go with the NewConnector
function, you must first add the following to your import
declaration:
"github.com/databricks/databricks-sql-go/auth/oauth/m2m"
Then use the following code snippet and the code example in Connect with the NewConnector function, which assumes that you have set the following environment variables:
DATABRICKS_SERVER_HOSTNAME
set to the Server Hostname value for your cluster or SQL warehouse.DATABRICKS_HTTP_PATH
, set to HTTP Path value for your cluster or SQL warehouse.DATABRICKS_CLIENT_ID
, set to the service principal’s UUID or Application ID value.DATABRICKS_CLIENT_SECRET
, set to the Secret value for the service principal’s OAuth secret.
To set environment variables, see your operating system’s documentation.
authenticator := m2m.NewAuthenticator(
os.Getenv("DATABRICKS_CLIENT_ID"),
os.Getenv("DATABRICKS_CLIENT_SECRET"),
os.Getenv("DATABRICKS_SERVER_HOSTNAME"),
)
connector, err := dbsql.NewConnector(
dbsql.WithServerHostname(os.Getenv("DATABRICKS_SERVER_HOSTNAME")),
dbsql.WithHTTPPath(os.Getenv("DATABRICKS_HTTP_PATH")),
dbsql.WithPort(443),
dbsql.WithAuthenticator(authenticator),
)
Query data
The following code example demonstrates how to call the Databricks SQL Driver for Go to run a basic SQL query on a Databricks compute resource. This command returns the first two rows from the trips
table in the samples
catalog’s nyctaxi
schema.
This code example retrieves the DSN connection string from an environment variable named DATABRICKS_DSN
.
package main
import (
"database/sql"
"fmt"
"os"
"time"
_ "github.com/databricks/databricks-sql-go"
)
func main() {
dsn := os.Getenv("DATABRICKS_DSN")
if dsn == "" {
panic("No connection string found." +
"Set the DATABRICKS_DSN environment variable, and try again.")
}
db, err := sql.Open("databricks", dsn)
if err != nil {
panic(err)
}
defer db.Close()
var (
tpep_pickup_datetime time.Time
tpep_dropoff_datetime time.Time
trip_distance float64
fare_amount float64
pickup_zip int
dropoff_zip int
)
rows, err := db.Query("SELECT * FROM samples.nyctaxi.trips LIMIT 2")
if err != nil {
panic(err)
}
defer rows.Close()
fmt.Print("tpep_pickup_datetime,",
"tpep_dropoff_datetime,",
"trip_distance,",
"fare_amount,",
"pickup_zip,",
"dropoff_zip\n")
for rows.Next() {
err := rows.Scan(&tpep_pickup_datetime,
&tpep_dropoff_datetime,
&trip_distance,
&fare_amount,
&pickup_zip,
&dropoff_zip)
if err != nil {
panic(err)
}
fmt.Print(tpep_pickup_datetime, ",",
tpep_dropoff_datetime, ",",
trip_distance, ",",
fare_amount, ",",
pickup_zip, ",",
dropoff_zip, "\n")
}
err = rows.Err()
if err != nil {
panic(err)
}
}
Manage files in Unity Catalog volumes
The Databricks SQL Driver enables you to write local files to Unity Catalog volumes, download files from volumes, and delete files from volumes, as shown in the following example:
package main
import (
"context"
"database/sql"
"os"
_ "github.com/databricks/databricks-sql-go"
"github.com/databricks/databricks-sql-go/driverctx"
)
func main() {
dsn := os.Getenv("DATABRICKS_DSN")
if dsn == "" {
panic("No connection string found." +
"Set the DATABRICKS_DSN environment variable, and try again.")
}
db, err := sql.Open("databricks", dsn)
if err != nil {
panic(err)
}
defer db.Close()
// For writing local files to volumes and downloading files from volumes,
// you must first specify the path to the local folder that contains the
// files to be written or downloaded.
// For multiple folders, add their paths to the following string array.
// For deleting files in volumes, this string array is ignored but must
// still be provided, so in that case its value can be set for example
// to an empty string.
ctx := driverctx.NewContextWithStagingInfo(
context.Background(),
[]string{"/tmp/"},
)
// Write a local file to the path in the specified volume.
// Specify OVERWRITE to overwrite any existing file in that path.
db.ExecContext(ctx, "PUT '/tmp/my-data.csv' INTO '/Volumes/main/default/my-volume/my-data.csv' OVERWRITE")
// Download a file from the path in the specified volume.
db.ExecContext(ctx, "GET '/Volumes/main/default/my-volume/my-data.csv' TO '/tmp/my-downloaded-data.csv'")
// Delete a file from the path in the specified volume.
db.ExecContext(ctx, "REMOVE '/Volumes/main/default/my-volume/my-data.csv'")
db.Close()
}
Logging
Use github.com/databricks/databricks-sql-go/logger
to log messages that the Databricks SQL Driver for Go emits. The following code example uses sql.Open()
to create a database handle through a DSN connection string. This code example retrieves the DSN connection string from an environment variable named DATABRICKS_DSN
. All log messages that are emitted at the debug
level and below are written to the results.log
file.
package main
import (
"database/sql"
"io"
"log"
"os"
_ "github.com/databricks/databricks-sql-go"
dbsqllog "github.com/databricks/databricks-sql-go/logger"
)
func main() {
dsn := os.Getenv("DATABRICKS_DSN")
// Use the specified file for logging messages to.
file, err := os.Create("results.log")
if err != nil {
log.Fatal(err)
}
defer file.Close()
writer := io.Writer(file)
// Log messages at the debug level and below.
if err := dbsqllog.SetLogLevel("debug"); err != nil {
log.Fatal(err)
}
// Log messages to the file.
dbsqllog.SetLogOutput(writer)
if dsn == "" {
panic("Error: Cannot connect. No connection string found. " +
"Set the DATABRICKS_DSN environment variable, and try again.")
}
db, err := sql.Open("databricks", dsn)
if err != nil {
panic(err)
}
defer db.Close()
if err := db.Ping(); err != nil {
panic(err)
}
}
Testing
To test your code, use Go test frameworks such as the testing standard library. To test your code under simulated conditions without calling Databricks REST API endpoints or changing the state of your Databricks accounts or workspaces, use Go mocking libraries such as testfify.
For example, given the following file named helpers.go
containing a GetDBWithDSNPAT
function that returns a Databricks workspace connection, a GetNYCTaxiTrips
function that returns data from the trips
table in the samples
catalog’s nyctaxi
schema, and a PrintNYCTaxiTrips
that prints the returned data:
package main
import (
"database/sql"
"fmt"
"strconv"
"time"
)
func GetDBWithDSNPAT(dsn string) (*sql.DB, error) {
db, err := sql.Open("databricks", dsn)
if err != nil {
return nil, err
}
return db, nil
}
func GetNYCTaxiTrips(db *sql.DB, numRows int) (*sql.Rows, error) {
rows, err := db.Query("SELECT * FROM samples.nyctaxi.trips LIMIT " + strconv.Itoa(numRows))
if err != nil {
return nil, err
}
return rows, nil
}
func PrintNYCTaxiTrips(rows *sql.Rows) {
var (
tpep_pickup_datetime time.Time
tpep_dropoff_datetime time.Time
trip_distance float64
fare_amount float64
pickup_zip int
dropoff_zip int
)
fmt.Print(
"tpep_pickup_datetime,",
"tpep_dropoff_datetime,",
"trip_distance,",
"fare_amount,",
"pickup_zip,",
"dropoff_zip\n",
)
for rows.Next() {
err := rows.Scan(
&tpep_pickup_datetime,
&tpep_dropoff_datetime,
&trip_distance,
&fare_amount,
&pickup_zip,
&dropoff_zip,
)
if err != nil {
panic(err)
}
fmt.Print(
tpep_pickup_datetime, ",",
tpep_dropoff_datetime, ",",
trip_distance, ",",
fare_amount, ",",
pickup_zip, ",",
dropoff_zip, "\n",
)
}
err := rows.Err()
if err != nil {
panic(err)
}
}
And given the following file named main.go
that calls these functions:
package main
import (
"os"
)
func main() {
db, err := GetDBWithDSNPAT(os.Getenv("DATABRICKS_DSN"))
if err != nil {
panic(err)
}
rows, err := GetNYCTaxiTrips(db, 2)
if err != nil {
panic(err)
}
PrintNYCTaxiTrips(rows)
}
The following file named helpers_test.go
tests whether the GetNYCTaxiTrips
function returns the expected response. Rather than creating a real connection to the target workspace, this test mocks a sql.DB
object. The test also mocks some data that conforms to the schema and values that are in the real data. The test returns the mocked data through the mocked connection and then checks whether one of the mocked data rows’ values matches the expected value.
package main
import (
"database/sql"
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/mock"
)
// Define an interface that contains a method with the same signature
// as the real GetNYCTaxiTrips function that you want to test.
type MockGetNYCTaxiTrips interface {
GetNYCTaxiTrips(db *sql.DB, numRows int) (*sql.Rows, error)
}
// Define a struct that represents the receiver of the interface's method
// that you want to test.
type MockGetNYCTaxiTripsObj struct {
mock.Mock
}
// Define the behavior of the interface's method that you want to test.
func (m *MockGetNYCTaxiTripsObj) GetNYCTaxiTrips(db *sql.DB, numRows int) (*sql.Rows, error) {
args := m.Called(db, numRows)
return args.Get(0).(*sql.Rows), args.Error(1)
}
func TestGetNYCTaxiTrips(t *testing.T) {
// Instantiate the receiver.
mockGetNYCTaxiTripsObj := new(MockGetNYCTaxiTripsObj)
// Define how the mock function should be called and what it should return.
// We're not concerned with whether the actual database is connected to--just
// what is returned.
mockGetNYCTaxiTripsObj.On("GetNYCTaxiTrips", mock.Anything, mock.AnythingOfType("int")).Return(&sql.Rows{}, nil)
// Call the mock function that you want to test.
rows, err := mockGetNYCTaxiTripsObj.GetNYCTaxiTrips(nil, 2)
// Assert that the mock function was called as expected.
mockGetNYCTaxiTripsObj.AssertExpectations(t)
// Assert that the mock function returned what you expected.
assert.NotNil(t, rows)
assert.Nil(t, err)
}
Because the GetNYCTaxiTrips
function contains a SELECT
statement and therefore does not change the state of the trips
table, mocking is not absolutely required in this example. However, mocking enables you to quickly run your tests without waiting for an actual connection to be made with the workspace. Also, mocking enables you to run simulated tests multiple times for functions that might change a table’s state, such as INSERT INTO
, UPDATE
, and DELETE FROM
.
Additional resources
The Databricks SQL Driver for Go repository on GitHub
The database/sql package home page
The Databricks SQL Driver for Go examples on GitHub