dbsql

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Published: Apr 10, 2024 License: Apache-2.0 Imports: 27 Imported by: 23

README

Databricks SQL Driver for Go

Description

This repo contains a Databricks SQL Driver for Go's database/sql package. It can be used to connect and query Databricks clusters and SQL Warehouses.

Documentation

See doc.go for full documentation or the Databrick's documentation for SQL Driver for Go.

Usage

import (
  "context"
  "database/sql"
  _ "github.com/databricks/databricks-sql-go"
)

db, err := sql.Open("databricks", "token:********@********.databricks.com:443/sql/1.0/endpoints/********")
if err != nil {
  panic(err)
}
defer db.Close()


rows, err := db.QueryContext(context.Background(), "SELECT 1")
defer rows.Close()

Additional usage examples are available here.

Connecting with DSN (Data Source Name)

The DSN format is:

token:[your token]@[Workspace hostname]:[Port number][Endpoint HTTP Path]?param=value

You can set query timeout value by appending a timeout query parameter (in seconds) and you can set max rows to retrieve per network request by setting the maxRows query parameter:

token:[your token]@[Workspace hostname]:[Port number][Endpoint HTTP Path]?timeout=1000&maxRows=1000

You can turn on Cloud Fetch to increase the performance of extracting large query results by fetching data in parallel via cloud storage (more info here). To turn on Cloud Fetch, append useCloudFetch=true. You can also set the number of concurrently fetching goroutines by setting the maxDownloadThreads query parameter (default is 10):

token:[your token]@[Workspace hostname]:[Port number][Endpoint HTTP Path]?useCloudFetch=true&maxDownloadThreads=3
Connecting with a new Connector

You can also connect with a new connector object. For example:

import (
"database/sql"
  _ "github.com/databricks/databricks-sql-go"
)

connector, err := dbsql.NewConnector(
  dbsql.WithServerHostname(<Workspace hostname>),
  dbsql.WithPort(<Port number>),
  dbsql.WithHTTPPath(<Endpoint HTTP Path>),
  dbsql.WithAccessToken(<your token>)
)
if err != nil {
  log.Fatal(err)
}
db := sql.OpenDB(connector)
defer db.Close()

View doc.go or connector.go to understand all the functional options available when creating a new connector object.

Develop

Lint

We use golangci-lint as the lint tool. If you use vs code, just add the following settings:

{
    "go.lintTool": "golangci-lint",
    "go.lintFlags": [
        "--fast"
    ]
}
Unit Tests
go test

Issues

If you find any issues, feel free to create an issue or send a pull request directly.

Contributing

See CONTRIBUTING.md

License

Apache 2.0

Documentation

Overview

Package dbsql implements the go driver to Databricks SQL

Usage

Clients should use the database/sql package in conjunction with the driver:

import (
	"database/sql"

	_ "github.com/databricks/databricks-sql-go"
)

func main() {
	db, err := sql.Open("databricks", "token:<token>@<hostname>:<port>/<endpoint_path>")

	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()
}

Connection via DSN (Data Source Name)

Use sql.Open() to create a database handle via a data source name string:

db, err := sql.Open("databricks", "<dsn_string>")

The DSN format is:

token:[my_token]@[hostname]:[port]/[endpoint http path]?param=value

Supported optional connection parameters can be specified in param=value and include:

  • catalog: Sets the initial catalog name in the session
  • schema: Sets the initial schema name in the session
  • maxRows: Sets up the max rows fetched per request. Default is 100000
  • timeout: Adds timeout (in seconds) for the server query execution. Default is no timeout
  • userAgentEntry: Used to identify partners. Set as a string with format <isv-name+product-name>
  • useCloudFetch: Used to enable cloud fetch for the query execution. Default is false
  • maxDownloadThreads: Sets up the max number of concurrent workers for cloud fetch. Default is 10
  • authType: Specifies the desired authentication type. Valid values are: Pat, OauthM2M, OauthU2M
  • accessToken: Personal access token. Required if authType set to Pat
  • clientID: Specifies the client ID to use with OauthM2M
  • clientSecret: Specifies the client secret to use with OauthM2M

Supported optional session parameters can be specified in param=value and include:

  • ansi_mode: (Boolean string). Session statements will adhere to rules defined by ANSI SQL specification.
  • timezone: (e.g. "America/Los_Angeles"). Sets the timezone of the session

Connection via new connector object

Use sql.OpenDB() to create a database handle via a new connector object created with dbsql.NewConnector():

import (
	"database/sql"
	dbsql "github.com/databricks/databricks-sql-go"
)

func main() {
	connector, err := dbsql.NewConnector(
		dbsql.WithServerHostname(<hostname>),
		dbsql.WithPort(<port>),
		dbsql.WithHTTPPath(<http_path>),
		dbsql.WithAccessToken(<my_token>)
	)
	if err != nil {
		log.Fatal(err)
	}

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

Supported functional options include:

  • WithServerHostname(<hostname> string): Sets up the server hostname. The hostname can be prefixed with "http:" or "https:" to specify a protocol to use. Mandatory
  • WithPort(<port> int): Sets up the server port. Mandatory
  • WithAccessToken(<my_token> string): Sets up the Personal Access Token. Mandatory
  • WithHTTPPath(<http_path> string): Sets up the endpoint to the warehouse. Mandatory
  • WithInitialNamespace(<catalog> string, <schema> string): Sets up the catalog and schema name in the session. Optional
  • WithMaxRows(<max_rows> int): Sets up the max rows fetched per request. Default is 100000. Optional
  • WithSessionParams(<params_map> map[string]string): Sets up session parameters including "timezone" and "ansi_mode". Optional
  • WithTimeout(<timeout> Duration). Adds timeout (in time.Duration) for the server query execution. Default is no timeout. Optional
  • WithUserAgentEntry(<isv-name+product-name> string). Used to identify partners. Optional
  • WithCloudFetch (bool). Used to enable cloud fetch for the query execution. Default is false. Optional
  • WithMaxDownloadThreads (<num_threads> int). Sets up the max number of concurrent workers for cloud fetch. Default is 10. Optional
  • WithAuthenticator (<authenticator> auth.Authenticator). Sets up authentication. Required if neither access token or client credentials are provided.
  • WithClientCredentials(<clientID> string, <clientSecret> string). Sets up Oauth M2M authentication.

Query cancellation and timeout

Cancelling a query via context cancellation or timeout is supported.

// Set up context timeout
ctx, cancel := context.WithTimeout(context.Background(), 30 * time.Second)
defer cancel()

// Execute query. Query will be cancelled after 30 seconds if still running
res, err := db.ExecContext(ctx, "CREATE TABLE example(id int, message string)")

CorrelationId and ConnId

Use the driverctx package under driverctx/ctx.go to add CorrelationId and ConnId to the context. CorrelationId and ConnId makes it convenient to parse and create metrics in logging.

**Connection Id** Internal id to track what happens under a connection. Connections can be reused so this would track across queries.

**Query Id** Internal id to track what happens under a query. Useful because the same query can be used with multiple connections.

**Correlation Id** External id, such as request ID, to track what happens under a request. Useful to track multiple connections in the same request.

ctx := dbsqlctx.NewContextWithCorrelationId(context.Background(), "workflow-example")

Logging

Use the logger package under logger.go to set up logging (from zerolog). By default, logging level is `warn`. If you want to disable logging, use `disabled`. The user can also utilize Track() and Duration() to custom log the elapsed time of anything tracked.

import (
	dbsqllog "github.com/databricks/databricks-sql-go/logger"
	dbsqlctx "github.com/databricks/databricks-sql-go/driverctx"
)

func main() {
	// Optional. Set the logging level with SetLogLevel()
	if err := dbsqllog.SetLogLevel("debug"); err != nil {
		log.Fatal(err)
	}

	// Optional. Set logging output with SetLogOutput()
	// Default is os.Stderr. If running in terminal, logger will use ConsoleWriter to prettify logs
	dbsqllog.SetLogOutput(os.Stdout)

	// Optional. Set correlation id with NewContextWithCorrelationId
	ctx := dbsqlctx.NewContextWithCorrelationId(context.Background(), "workflow-example")

	// Optional. Track time spent and log elapsed time
	msg, start := logger.Track("Run Main")
	defer log.Duration(msg, start)

	db, err := sql.Open("databricks", "<dsn_string>")
	...
}

The result log may look like this:

{"level":"debug","connId":"01ed6545-5669-1ec7-8c7e-6d8a1ea0ab16","corrId":"workflow-example","queryId":"01ed6545-57cc-188a-bfc5-d9c0eaf8e189","time":1668558402,"message":"Run Main elapsed time: 1.298712292s"}

Programmatically Retrieving Connection and Query Id

Use the driverctx package under driverctx/ctx.go to add callbacks to the query context to receive the connection id and query id.

import (
	"github.com/databricks/databricks-sql-go/driverctx"
)

func main() {

	...

	qidCallback := func(id string) {
		fmt.Println("query id: " + id)
	}

	connIdCallback := func(id string) {
		fmt.Println("connection id: " + id)
	}

	ctx := context.Background()
	ctx = driverctx.NewContextWithQueryIdCallback(ctx, qidCallback)
	ctx = driverctx.NewContextWithConnIdCallback(ctx, connIdCallback)

	rows, err1 := db.QueryContext(ctx, `select * from sometable`)

	...

}

Query parameters

Passing parameters to a query is supported when run against servers with version DBR 14.1.

p := dbsql.Parameter{Name: "p_bool", Value: true},
rows, err1 := db.QueryContext(ctx, `select * from sometable where condition=:p_bool`,dbsql.Parameter{Name: "p_bool", Value: true})

For complex types, you can specify the SQL type using the dbsql.Parameter type field. If this field is set, the value field MUST be set to a string.

Staging Ingestion

The Go driver now supports staging operations. In order to use a staging operation, you first must update the context with a list of folders that you are allowing the driver to access.

ctx := driverctx.NewContextWithStagingInfo(context.Background(), []string{"staging/"})

After doing so, you can execute staging operations using this context using the exec context.

_, err1 := db.ExecContext(ctx, `PUT 'staging/file.csv' INTO '/Volumes/main/staging_test/e2etests/file.csv' OVERWRITE`)

Errors

There are three error types exposed via dbsql/errors

DBDriverError - An error in the go driver. Example: unimplemented functionality, invalid driver state, errors processing a server response, etc.

DBRequestError - An error that is caused by an invalid request. Example: permission denied, invalid http path or other connection parameter, resource not available, etc.

DBExecutionError - Any error that occurs after the SQL statement has been accepted such as a SQL syntax error, missing table, etc.

Each type has a corresponding sentinel value which can be used with errors.Is() to determine if one of the types is present in an error chain.

DriverError
RequestError
ExecutionError

Example usage:

import (
	fmt
	errors
	dbsqlerr "github.com/databricks/databricks-sql-go/errors"
)

func main() {
	...
	_, err := db.ExecContext(ogCtx, `Select id from range(100)`)
	if err != nil {
		if errors.Is(err, dbsqlerr.ExecutionError) {
			var execErr dbsqlerr.DBExecutionError
			if ok := errors.As(err, &execError); ok {
					fmt.Printf("%s, corrId: %s, connId: %s, queryId: %s, sqlState: %s, isRetryable: %t, retryAfter: %f seconds",
					execErr.Error(),
					execErr.CorrelationId(),
					execErr.ConnectionId(),
					execErr.QueryId(),
					execErr.SqlState(),
				    execErr.IsRetryable(),
					execErr.RetryAfter().Seconds(),
				)
			}
		}
		...
	}
	...
}

See the documentation for dbsql/errors for more information.

Retrieving Arrow Batches

The driver supports the ability to retrieve Apache Arrow record batches. To work with record batches it is necessary to use sql.Conn.Raw() to access the underlying driver connection to retrieve a driver.Rows instance. The driver exposes two public interfaces for working with record batches from the rows sub-package:

type Rows interface {
	GetArrowBatches(context.Context) (ArrowBatchIterator, error)
}

type ArrowBatchIterator interface {
	// Retrieve the next arrow.Record.
	// Will return io.EOF if there are no more records
	Next() (arrow.Record, error)

	// Return true if the iterator contains more batches, false otherwise.
	HasNext() bool

	// Release any resources in use by the iterator.
	Close()
}

The driver.Rows instance retrieved using Conn.Raw() can be converted to a Databricks Rows instance via a type assertion, then use GetArrowBatches() to retrieve a batch iterator. If the ArrowBatchIterator is not closed it will leak resources, such as the underlying connection. Calling code must call Release() on records returned by DBSQLArrowBatchIterator.Next().

Example usage:

import (
	...
	dbsqlrows "github.com/databricks/databricks-sql-go/rows"
)

func main() {
	...
	db := sql.OpenDB(connector)
	defer db.Close()

	conn, _ := db.Conn(context.BackGround())
	defer conn.Close()

	query := `select * from main.default.taxi_trip_data`

	var rows driver.Rows
	var err error
	err = conn.Raw(func(d interface{}) error {
		rows, err = d.(driver.QueryerContext).QueryContext(ctx, query, nil)
		return err
	})

	if err != nil {
		log.Fatalf("unable to run the query. err: %v", err)
	}
	defer rows.Close()

	batches, err := rows.(dbsqlrows.Rows).GetArrowBatches(context.BackGround())
	if err != nil {
		log.Fatalf("unable to get arrow batches. err: %v", err)
	}

	var iBatch, nRows int
	for batches.HasNext() {
		b, err := batches.Next()
		if err != nil {
			log.Fatalf("Failure retrieving batch. err: %v", err)
		}

		log.Printf("batch %v: nRecords=%v\n", iBatch, b.NumRows())
		iBatch += 1
		nRows += int(b.NumRows())
		b.Release()
	}
	log.Printf("NRows: %v\n", nRows)
}

Supported Data Types

==================================

Databricks Type --> Golang Type

==================================

BOOLEAN --> bool

TINYINT --> int8

SMALLINT --> int16

INT --> int32

BIGINT --> int64

FLOAT --> float32

DOUBLE --> float64

VOID --> nil

STRING --> string

DATE --> time.Time

TIMESTAMP --> time.Time

DECIMAL(p,s) --> sql.RawBytes

BINARY --> sql.RawBytes

ARRAY<elementType> --> sql.RawBytes

STRUCT --> sql.RawBytes

MAP<keyType, valueType> --> sql.RawBytes

INTERVAL (year-month) --> string

INTERVAL (day-time) --> string

For ARRAY, STRUCT, and MAP types, sql.Scan can cast sql.RawBytes to JSON string, which can be unmarshalled to Golang arrays, maps, and structs. For example:

type structVal struct {
		StringField string `json:"string_field"`
		ArrayField  []int  `json:"array_field"`
}
type row struct {
	arrayVal  []int
	mapVal    map[string]int
	structVal structVal
}
res := []row{}

for rows.Next() {
	r := row{}
	tempArray := []byte{}
	tempStruct := []byte{}
	tempMap := []byte{}
	if err := rows.Scan(&tempArray, &tempMap, &tempStruct); err != nil {
		log.Fatal(err)
	}
	if err := json.Unmarshal(tempArray, &r.arrayVal); err != nil {
		log.Fatal(err)
	}
	if err := json.Unmarshal(tempMap, &r.mapVal); err != nil {
		log.Fatal(err)
	}
	if err := json.Unmarshal(tempStruct, &r.structVal); err != nil {
		log.Fatal(err)
	}
	res = append(res, r)
}

May generate the following row:

{arrayVal:[1,2,3] mapVal:{"key1":1} structVal:{"string_field":"string_val","array_field":[4,5,6]}}

Index

Constants

This section is empty.

Variables

View Source
var DriverVersion = "1.5.4" // update version before each release

Functions

func NewConnector

func NewConnector(options ...connOption) (driver.Connector, error)

NewConnector creates a connection that can be used with `sql.OpenDB()`. This is an easier way to set up the DB instead of having to construct a DSN string.

func Succeeded added in v1.5.0

func Succeeded(response *http.Response) bool

func WithAccessToken added in v0.2.0

func WithAccessToken(token string) connOption

WithAccessToken sets up the Personal Access Token. Mandatory for now.

func WithAuthenticator added in v1.3.0

func WithAuthenticator(authr auth.Authenticator) connOption

WithAuthenticator sets up the Authentication. Mandatory if access token is not provided.

func WithClientCredentials added in v1.5.0

func WithClientCredentials(clientID, clientSecret string) connOption

Setup of Oauth M2m authentication

func WithCloudFetch added in v1.4.0

func WithCloudFetch(useCloudFetch bool) connOption

WithCloudFetch sets up the use of cloud fetch for query execution. Default is false.

func WithHTTPPath added in v0.2.0

func WithHTTPPath(path string) connOption

WithHTTPPath sets up the endpoint to the warehouse. Mandatory.

func WithInitialNamespace added in v0.2.0

func WithInitialNamespace(catalog, schema string) connOption

Sets the initial catalog name and schema name in the session. Use <select * from foo> instead of <select * from catalog.schema.foo>

func WithMaxDownloadThreads added in v1.4.0

func WithMaxDownloadThreads(numThreads int) connOption

WithMaxDownloadThreads sets up maximum download threads for cloud fetch. Default is 10.

func WithMaxRows added in v0.2.0

func WithMaxRows(n int) connOption

WithMaxRows sets up the max rows fetched per request. Default is 10000

func WithPort added in v0.2.0

func WithPort(port int) connOption

WithPort sets up the server port. Mandatory.

func WithRetries added in v1.1.0

func WithRetries(retryMax int, retryWaitMin time.Duration, retryWaitMax time.Duration) connOption

WithRetries sets up retrying logic. Sane defaults are provided. Negative retryMax will disable retry behavior By default retryWaitMin = 1 * time.Second By default retryWaitMax = 30 * time.Second By default retryMax = 4

func WithServerHostname added in v0.2.0

func WithServerHostname(host string) connOption

WithServerHostname sets up the server hostname. Mandatory.

func WithSessionParams added in v0.2.0

func WithSessionParams(params map[string]string) connOption

Sessions params will be set upon opening the session by calling SET function. If using connection pool, session params can avoid successive calls of "SET ..."

func WithTimeout added in v0.2.0

func WithTimeout(n time.Duration) connOption

WithTimeout adds timeout for the server query execution. Default is no timeout.

func WithTransport added in v1.4.0

func WithTransport(t http.RoundTripper) connOption

WithTransport sets up the transport configuration to be used by the httpclient.

func WithUserAgentEntry added in v0.2.0

func WithUserAgentEntry(entry string) connOption

Used to identify partners. Set as a string with format <isv-name+product-name>.

Types

type Parameter added in v1.5.0

type Parameter struct {
	Name  string
	Type  SqlType
	Value any
}

type SqlType added in v1.5.0

type SqlType int
const (
	SqlUnkown SqlType = iota
	SqlString
	SqlDate
	SqlTimestamp
	SqlFloat
	SqlDecimal
	SqlDouble
	SqlInteger
	SqlBigInt
	SqlSmallInt
	SqlTinyInt
	SqlBoolean
	SqlIntervalMonth
	SqlIntervalDay
)

func (SqlType) String added in v1.5.0

func (s SqlType) String() string

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