Go Connector for TDengine

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[TDengine] provides Go database/sql driver as [taosSql][driver-go].

Remind

github.com/taosdata/driver-go/v2 is completely refactoring based on the v1 version. It also separates the built-in database operation interface database/sql/driver into the directory taosSql and put other advanced functions such as subscription and stmt in the directory af.

Install

Go 1.14+ is highly recommended for newly created projects.

go mod init taos-demo

import taosSql：

import (
    "database/sql"
    _ "github.com/taosdata/driver-go/v2/taosSql"
)

Use go mod for module management:

go mod tidy

Or go get to directly install it:

go get github.com/taosdata/driver-go/v2/taosSql

Usage

database/sql Standard

A simple use case：

package main

import (
    "database/sql"
    "fmt"
    "time"

    _ "github.com/taosdata/driver-go/v2/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
    }
    defer taos.Close()
    taos.Exec("create database if not exists test")
    taos.Exec("use 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)
    }
}

APIs that are worthy to have a check:

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

  This API will create a database/sql DB object, results with type *DB. DRIVER_NAME should be set as taosSql, and dataSourceName should be a URI like user:password@/tcp(host:port)/dbname. For HA use case, use user:password@/cfg/dbname to apply configs in /etc/taos/taos.cfg。

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

  Execute non resultset SQLs, like create, alter etc.

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

  Execute a query with resultset.

• func (db *DB) Close() error

  Close an DB object and disconnect.

Subscription

Open DB:

func Open(host, user, pass, db string, port int) (*Connector, error)

Subscribe:

func (conn *Connector) Subscribe(restart bool, topic string, sql string, interval time.Duration) (Subscriber, error)

Subscriber:

type Subscriber interface {
    Consume() (driver.Rows, error)
    Unsubscribe(keepProgress bool)
}

Check sample code for subscription at examples/taoslogtail.go.

restful implementation of the database/sql standard interface

A simple use case：

package main

import (
    "database/sql"
    "fmt"
    "time"

    _ "github.com/taosdata/driver-go/v2/taosRestful"
)

func main() {
    var taosDSN = "root:taosdata@http(localhost:6041)/"
    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 test.tb1 (ts timestamp, a int)")
    _, err = taos.Exec("insert into test.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 test.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)
    }
}

Usage of taosRestful

import

import (
    "database/sql"
    _ "github.com/taosdata/driver-go/v2/taosRestful"
)

Introduce

import (
    "database/sql"
    _ "github.com/taosdata/driver-go/v2/taosRestful"
)

The driverName of sql.Open is taosRestful

The DSN format is:

database username:database password@connection-method(domain or ip:port)/[database][? Parameter]

Example:

root:taosdata@http(localhost:6041)/test?readBufferSize=52428800

Parameters:

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

Usage restrictions

Since the restful interface is stateless, the use db syntax will not work, you need to put the db name into the sql statement, 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 an 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. This method is supported by taosadapter since TDengine 2.4.0.5. Executing the create database statement when the specified db does not exist will not report an error, while executing other queries or inserts will report an error. The example is as follows:

package main

import (
    "database/sql"
    "fmt"
    "time"

    _ "github.com/taosdata/driver-go/v2/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)
    }
}

Directory structure

driver-go
├── af //advanced function
├── common //common function and constants
├── errors // error type
├── examples //examples
├── go.mod
├── go.sum
├── README-CN.md
├── README.md
├── taosRestful // database operation standard interface (restful)
├── taosSql // database operation standard interface
├── types // inner type
└── wrapper // cgo wrapper

Link

driver-go: https://github.com/taosdata/driver-go

TDengine: https://github.com/taosdata/TDengine