TDengine Go Connector

driver-go provides two ways to establish connections. One is native connection, which connects to TDengine instances natively through the TDengine client driver (taosc), supporting data writing, querying, subscriptions, schemaless writing, and bind interface. The other is the REST connection, which connects to TDengine instances via the REST interface provided by taosAdapter. The set of features implemented by the REST connection differs slightly from those implemented by the native connection.

This article describes how to install driver-go and connect to TDengine clusters and perform basic operations such as data query and data writing through driver-go.

The source code of driver-go is hosted on .

Native connections are supported on the same platforms as the TDengine client driver. REST connections are supported on all platforms that can run Go.

Version support

Please refer to version support list

Supported features

A “native connection” is established by the connector directly to the TDengine instance via the TDengine client driver (taosc). The supported functional features are:

• Normal queries
• Continuous queries
• Subscriptions
• Schemaless interface
• Parameter binding interface

REST connection

A “REST connection” is a connection between the application and the TDengine instance via the REST API provided by the taosAdapter component. The following features are supported:

• Normal queries
• Continuous queries

Pre-installation preparation

• Install Go development environment (Go 1.14 and above, GCC 4.8.5 and above)

• If you use the native connector, please install the TDengine client driver. Please refer to Install Client Driver for specific steps

Configure the environment variables and check the command.

• go env
• gcc -v

Use go get to install

go get -u github.com/taosdata/driver-go/v3@latest

1. Initialize the project with the go mod command.

2. Introduce taosSql

   import (
     "database/sql"
     _ "github.com/taosdata/driver-go/v3/taosSql"
   )

3. Update the dependency packages with go mod tidy.

   go mod tidy

4. Run the program with go run taos-demo or compile the binary with the go build command.

   go run taos-demo
   go build

Establishing a connection

Data source name (DSN)

Data source names have a standard format, e.g. , but no type prefix (square brackets indicate optionally):

[username[:password]@][protocol[(address)]]/[dbname][?param1=value1&...&paramN=valueN]

DSN in full form.

Connecting via connector

• native connection
• REST connection
• WebSocket connection

taosSql implements Go’s database/sql/driver interface via cgo. You can use the interface by simply introducing the driver.

Use taosSql as driverName and use a correct DSN as dataSourceName, DSN supports the following parameters.

• configPath specifies the taos.cfg directory

For example:

package main
import (
    "database/sql"
    "fmt"
    _ "github.com/taosdata/driver-go/v3/taosSql"
)
func main() {
    var taosUri = "root:taosdata@tcp(localhost:6030)/"
    taos, err := sql.Open("taosSql", taosUri)
    if err != nil {
        fmt.Println("failed to connect TDengine, err:", err)
        return
    }
}

taosRestful implements Go’s database/sql/driver interface via http client. You can use the interface by simply introducing the driver.

Use taosRestful as driverName and use a correct DSN as dataSourceName with the following parameters supported by the DSN.

• disableCompression whether to accept compressed data, default is true do not accept compressed data, set to false if transferring data using gzip compression.
• readBufferSize The default size of the buffer for reading data is 4K (4096), which can be adjusted upwards when the query result has a lot of data.

For example:

package main
import (
    "database/sql"
    "fmt"
    _ "github.com/taosdata/driver-go/v3/taosRestful"
)
func main() {
    var taosUri = "root:taosdata@http(localhost:6041)/"
    taos, err := sql.Open("taosRestful", taosUri)
    if err != nil {
        fmt.Println("failed to connect TDengine, err:", err)
        return
    }
}

taosRestful implements Go’s database/sql/driver interface via http client. You can use the interface by simply introducing the driver (driver-go minimum version 3.0.2).

Use taosWS as driverName and use a correct DSN as dataSourceName with the following parameters supported by the DSN.

• writeTimeout The timeout to send data via WebSocket.
• readTimeout The timeout to receive response data via WebSocket.

For example:

package main
import (
    "database/sql"
    "fmt"
    _ "github.com/taosdata/driver-go/v3/taosWS"
)
func main() {
    var taosUri = "root:taosdata@ws(localhost:6041)/"
    taos, err := sql.Open("taosWS", taosUri)
    if err != nil {
        fmt.Println("failed to connect TDengine, err:", err)
        return
    }
}

Usage examples

Write data

SQL Write

package main
import (
    "database/sql"
    "fmt"
    "log"
)
func createStable(taos *sql.DB) {
    _, err := taos.Exec("CREATE DATABASE power")
    if err != nil {
        log.Fatalln("failed to create database, err:", err)
    }
    _, err = taos.Exec("CREATE STABLE power.meters (ts TIMESTAMP, current FLOAT, voltage INT, phase FLOAT) TAGS (location BINARY(64), groupId INT)")
    if err != nil {
        log.Fatalln("failed to create stable, err:", err)
    }
}
func insertData(taos *sql.DB) {
    sql := `INSERT INTO power.d1001 USING power.meters TAGS('California.SanFrancisco', 2) VALUES ('2018-10-03 14:38:05.000', 10.30000, 219, 0.31000) ('2018-10-03 14:38:15.000', 12.60000, 218, 0.33000) ('2018-10-03 14:38:16.800', 12.30000, 221, 0.31000)
    power.d1002 USING power.meters TAGS('California.SanFrancisco', 3) VALUES ('2018-10-03 14:38:16.650', 10.30000, 218, 0.25000)
    power.d1003 USING power.meters TAGS('California.LosAngeles', 2) VALUES ('2018-10-03 14:38:05.500', 11.80000, 221, 0.28000) ('2018-10-03 14:38:16.600', 13.40000, 223, 0.29000)
    power.d1004 USING power.meters TAGS('California.LosAngeles', 3) VALUES ('2018-10-03 14:38:05.000', 10.80000, 223, 0.29000) ('2018-10-03 14:38:06.500', 11.50000, 221, 0.35000)`
    result, err := taos.Exec(sql)
    if err != nil {
        log.Fatalln("failed to insert, err:", err)
    }
    rowsAffected, err := result.RowsAffected()
    if err != nil {
    }
    fmt.Println("RowsAffected", rowsAffected)
}
func main() {
    var taosDSN = "root:taosdata@http(localhost:6041)/"
    taos, err := sql.Open("taosRestful", taosDSN)
    if err != nil {
        log.Fatalln("failed to connect TDengine, err:", err)
    }
    defer taos.Close()
    createStable(taos)
    insertData(taos)
}

view source code

InfluxDB line protocol write

view source code

OpenTSDB Telnet line protocol write

package main
import (
    "log"
    "github.com/taosdata/driver-go/v3/af"
)
func prepareDatabase(conn *af.Connector) {
    _, err := conn.Exec("CREATE DATABASE test")
    if err != nil {
        panic(err)
    }
    _, err = conn.Exec("USE test")
    if err != nil {
        panic(err)
    }
}
func main() {
    conn, err := af.Open("localhost", "root", "taosdata", "", 6030)
    if err != nil {
        log.Fatalln("fail to connect, err:", err)
    }
    defer conn.Close()
    prepareDatabase(conn)
    var lines = []string{
        "meters.current 1648432611249 10.3 location=California.SanFrancisco groupid=2",
        "meters.current 1648432611250 12.6 location=California.SanFrancisco groupid=2",
        "meters.current 1648432611249 10.8 location=California.LosAngeles groupid=3",
        "meters.current 1648432611250 11.3 location=California.LosAngeles groupid=3",
        "meters.voltage 1648432611249 219 location=California.SanFrancisco groupid=2",
        "meters.voltage 1648432611250 218 location=California.SanFrancisco groupid=2",
        "meters.voltage 1648432611249 221 location=California.LosAngeles groupid=3",
        "meters.voltage 1648432611250 217 location=California.LosAngeles groupid=3",
    }
    err = conn.OpenTSDBInsertTelnetLines(lines)
    if err != nil {
        log.Fatalln("insert error:", err)
    }
}

view source code

OpenTSDB JSON line protocol write

package main
import (
    "log"
    "github.com/taosdata/driver-go/v3/af"
)
func prepareDatabase(conn *af.Connector) {
    _, err := conn.Exec("CREATE DATABASE test")
    if err != nil {
        panic(err)
    }
    _, err = conn.Exec("USE test")
    if err != nil {
        panic(err)
    }
}
func main() {
    conn, err := af.Open("localhost", "root", "taosdata", "", 6030)
    if err != nil {
        log.Fatalln("fail to connect, err:", err)
    }
    defer conn.Close()
    prepareDatabase(conn)
    payload := `[{"metric": "meters.current", "timestamp": 1648432611249, "value": 10.3, "tags": {"location": "California.SanFrancisco", "groupid": 2}},
                {"metric": "meters.voltage", "timestamp": 1648432611249, "value": 219, "tags": {"location": "California.LosAngeles", "groupid": 1}},
                {"metric": "meters.current", "timestamp": 1648432611250, "value": 12.6, "tags": {"location": "California.SanFrancisco", "groupid": 2}},
                {"metric": "meters.voltage", "timestamp": 1648432611250, "value": 221, "tags": {"location": "California.LosAngeles", "groupid": 1}}]`
    err = conn.OpenTSDBInsertJsonPayload(payload)
    if err != nil {
        log.Fatalln("insert error:", err)
    }
}

view source code

package main
import (
    "database/sql"
    "time"
    _ "github.com/taosdata/driver-go/v3/taosRestful"
)
func main() {
    var taosDSN = "root:taosdata@http(localhost:6041)/power"
    taos, err := sql.Open("taosRestful", taosDSN)
    if err != nil {
        log.Fatalln("failed to connect TDengine, err:", err)
    }
    defer taos.Close()
    rows, err := taos.Query("SELECT ts, current FROM meters LIMIT 2")
    if err != nil {
        log.Fatalln("failed to select from table, err:", err)
    }
    defer rows.Close()
    for rows.Next() {
        var r struct {
            ts      time.Time
            current float32
        }
        if err != nil {
            log.Fatalln("scan error:\n", err)
            return
        }
        log.Println(r.ts, r.current)
    }
}

view source code

More sample programs

• sample program

Since the REST interface is stateless, the use db syntax will not work. You need to put the db name into the SQL command, e.g. create table if not exists tb1 (ts timestamp, a int) to create table if not exists test.tb1 (ts timestamp, a int) otherwise it will report the error [0x217] Database not specified or available.

You can also put the db name in the DSN by changing root:taosdata@http(localhost:6041)/ to root:taosdata@http(localhost:6041)/test. Executing the create database statement when the specified db does not exist will not report an error while executing other queries or writing against that db will report an error.

The complete example is as follows.

package main
import (
    "database/sql"
    "fmt"
    "time"
    _ "github.com/taosdata/driver-go/v3/taosRestful"
)
func main() {
    var taosDSN = "root:taosdata@http(localhost:6041)/test"
    taos, err := sql.Open("taosRestful", taosDSN)
    if err != nil {
        fmt.Println("failed to connect TDengine, err:", err)
        return
    }
    defer taos.Close()
    taos.Exec("create database if not exists test")
    taos.Exec("create table if not exists tb1 (ts timestamp, a int)")
    _, err = taos.Exec("insert into tb1 values(now, 0)(now+1s,1)(now+2s,2)(now+3s,3)")
    if err != nil {
        fmt.Println("failed to insert, err:", err)
        return
    }
    rows, err := taos.Query("select * from tb1")
    if err != nil {
        fmt.Println("failed to select from table, err:", err)
        return
    }
    defer rows.Close()
    for rows.Next() {
        var r struct {
            ts time.Time
            a  int
        }
        err := rows.Scan(&r.ts, &r.a)
        if err != nil {
            fmt.Println("scan error:\n", err)
            return
        }
        fmt.Println(r.ts, r.a)
    }
}

Frequently Asked Questions

1. bind interface in database/sql crashes

   REST does not support parameter binding related interface. It is recommended to use db.Exec and db.Query.

2. error [0x217] Database not specified or available after executing other statements with use db statement

   The execution of SQL command in the REST interface is not contextual, so using use db statement will not work, see the usage restrictions section above.

3. use taosSql without error but use taosRestful with error [0x217] Database not specified or available

   Because the REST interface is stateless, using the use db statement will not take effect. See the usage restrictions section above.

4. readBufferSize parameter has no significant effect after being increased

5. disableCompression parameter is set to false when the query efficiency is reduced

   When set disableCompression parameter to false, the query result will be compressed by gzip and then transmitted, so you have to decompress the data by gzip after getting it.

6. go get command can’t get the package, or timeout to get the package

   Set Go proxy go env -w GOPROXY=https://goproxy.cn,direct.

Common APIs

database/sql API

• sql.Open(DRIVER_NAME string, dataSourceName string) *DB

  Use This API to open a DB, returning an object of type *DB.

info

This API is created successfully without checking permissions, but only when you execute a Query or Exec, and check if user/password/host/port is legal.

• func (db *DB) Exec(query string, args ...interface{}) (Result, error)

  sql.Open built-in method to execute non-query related SQL.

• func (db *DB) Query(query string, args ...interface{}) (*Rows, error)

  sql.Open Built-in method to execute query statements.

Advanced functions (af) API

The af package encapsulates TDengine advanced functions such as connection management, subscriptions, schemaless, parameter binding, etc.

Connection management

• af.Open(host, user, pass, db string, port int) (*Connector, error)

  This API creates a connection to taosd via cgo.

• func (conn *Connector) Close() error

  Closes the connection.

Subscribe

• func NewConsumer(conf *Config) (*Consumer, error)

Creates consumer group.

• func (c *Consumer) Subscribe(topics []string) error

Subscribes to topics.

• func (c *Consumer) Poll(timeout time.Duration) (*Result, error)

Polling information.

• func (c *Consumer) Commit(ctx context.Context, message unsafe.Pointer) error

Commit information.

• func (c *Consumer) FreeMessage(message unsafe.Pointer)

Free information.

• func (c *Consumer) Unsubscribe() error

Unsubscribe.

• func (c *Consumer) Close() error

Close consumer.

schemaless

• func (conn *Connector) InfluxDBInsertLines(lines []string, precision string) error

  Write to InfluxDB line protocol.

• func (conn *Connector) OpenTSDBInsertTelnetLines(lines []string) error

  Write OpenTDSB telnet protocol data.

• func (conn *Connector) OpenTSDBInsertJsonPayload(payload string) error

  Writes OpenTSDB JSON protocol data.

parameter binding

• func (conn *Connector) StmtExecute(sql string, params *param.Param) (res driver.Result, err error)

  Parameter bound single row insert.

• func (conn *Connector) InsertStmt() *insertstmt.InsertStmt

  Initialize the parameters.

• func (stmt *InsertStmt) Prepare(sql string) error

  Parameter binding preprocessing SQL statement.

• func (stmt *InsertStmt) SetTableName(name string) error

  Bind the table name parameter.

• func (stmt *InsertStmt) SetSubTableName(name string) error

  Parameter binding to set the sub table name.

• func (stmt *InsertStmt) BindParam(params []*param.Param, bindType *param.ColumnType) error

  Parameter bind multiple rows of data.

• Add to a parameter-bound batch.

• func (stmt *InsertStmt) Execute() error

  Execute a parameter binding.

• func (stmt *InsertStmt) GetAffectedRows() int

  Gets the number of affected rows inserted by the parameter binding.

• func (stmt *InsertStmt) Close() error

  Closes the parameter binding.

• func NewConsumer(config *Config) (*Consumer, error)

  Creates consumer group.

• func (c *Consumer) Subscribe(topic []string) error

  Subscribes to topics.

• func (c *Consumer) Poll(timeout time.Duration) (*Result, error)

  Polling information.

• func (c *Consumer) Commit(messageID uint64) error

  Commit information.

• func (c *Consumer) Close() error

  Close consumer.

For a complete example see GitHub sample file

parameter binding via WebSocket

• func NewConnector(config *Config) (*Connector, error)

  Create a connection.

• func (c *Connector) Init() (*Stmt, error)

  Initialize the parameters.

• func (c *Connector) Close() error

  Close the connection.

• func (s *Stmt) Prepare(sql string) error

  Parameter binding preprocessing SQL statement.

• func (s *Stmt) SetTableName(name string) error

  Bind the table name parameter.

• func (s *Stmt) SetTags(tags *param.Param, bindType *param.ColumnType) error

  Set tags.

• func (s *Stmt) BindParam(params []*param.Param, bindType *param.ColumnType) error

  Parameter bind multiple rows of data.

• func (s *Stmt) AddBatch() error

  Add to a parameter-bound batch.

• func (s *Stmt) Exec() error

  Execute a parameter binding.

• func (s *Stmt) Close() error

  Closes the parameter binding.

For a complete example see GitHub sample file