TDengine Go Client Library

driver-go is the official Go language client library for TDengine. It implements the database/sql package, the generic Go language interface to SQL databases. Go developers can use it to develop applications that access TDengine cluster data.

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 GitHub.

Version support

Please refer to version support list

Installation Steps

Pre-installation preparation

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

• If you use the native connection, 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

Manage with go mod

1. Initialize the project with the go mod command.

go mod init taos-demo

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. PEAR DB, but no type prefix (square brackets indicate optionally):

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

DSN in full form.

username:password@protocol(address)/dbname?param=value

Connecting via client library

taosRestful implements Go's database/sql/driver interface via http client. You can use the database/sql 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.

Sample programs

More sample programs

• sample program

Usage limitations

Since the REST API 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. 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 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. Cannot find the package github.com/taosdata/driver-go/v2/taosRestful

Change the github.com/taosdata/driver-go/v2 line in the require block of the go.mod file to github.com/taosdata/driver-go/v2 develop, then execute go mod tidy.

2. bind interface in database/sql crashes

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

3. 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.

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

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

5. Upgrade github.com/taosdata/driver-go/v2/taosRestful

Change the github.com/taosdata/driver-go/v2 line in the go.mod file to github.com/taosdata/driver-go/v2 develop, then execute go mod tidy.

6. readBufferSize parameter has no significant effect after being increased

Increasing readBufferSize will reduce the number of syscall calls when fetching results. If the query result is smaller, modifying this parameter will not improve performance significantly. If you increase the parameter value too much, the bottleneck will be parsing JSON data. If you need to optimize the query speed, you must adjust the value based on the actual situation to achieve the best query performance.

7. 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.

8. 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.

API Reference

Full API see driver-go documentation