SQL Tools

GreptimeDB uses SQL as its main query language and supports many popular SQL tools. This document guides you on how to use SQL tools with GreptimeDB.

Language drivers

It is recommended to use mature SQL drivers to query data.

Recommended libraries

Java

Java Database Connectivity (JDBC) is the JavaSoft specification of a standard application programming interface (API) that allows Java programs to access database management systems.

Many databases, such as MySQL or PostgreSQL, have implemented their own drivers based on the JDBC API. Since GreptimeDB supports multiple protocols, we use MySQL as an example to demonstrate how to use JDBC. If you want to use other protocols, just replace the MySQL driver with the corresponding driver.

Go

It is recommended to use the GORM library, which is popular and developer-friendly.

Installation

Java

If you are using Maven, add the following to your pom.xml dependencies list:

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.33</version>
</dependency>

Go

Use the following command to install the GORM library:

go get -u gorm.io/gorm

Then install the MySQL driver:

go get -u gorm.io/driver/mysql

Import the libraries in your code:

import (
    "gorm.io/gorm"
    "gorm.io/driver/mysql"
)

Connect to database

The following use MySQL as an example to demonstrate how to connect to GreptimeDB.

Java

public static Connection getConnection() throws IOException, ClassNotFoundException, SQLException {
    Properties prop = new Properties();
    prop.load(QueryJDBC.class.getResourceAsStream("/db-connection.properties"));

    String dbName = (String) prop.get("db.database-driver");
    String dbConnUrl = (String) prop.get("db.url");
    String dbUserName = (String) prop.get("db.username");
    String dbPassword = (String) prop.get("db.password");

    Class.forName(dbName);
    Connection dbConn = DriverManager.getConnection(dbConnUrl, dbUserName, dbPassword);

    return Objects.requireNonNull(dbConn, "Failed to make connection!");
}

You need a properties file to store the DB connection information. Place it in the resources directory and name it db-connection.properties. The file content is as follows:

# DataSource
db.database-driver=com.mysql.cj.jdbc.Driver
db.url=jdbc:mysql://localhost:4002/public
db.username=
db.password=

Or you can get the file from here.

Go

type Mysql struct {
  Host     string
  Port     string
  User     string
  Password string
  Database string

  DB *gorm.DB
}

m := &Mysql{
    Host:     "127.0.0.1",
    Port:     "4002", // default port for MySQL
    User:     "username",
    Password: "password",
    Database: "public",
}

dsn := fmt.Sprintf("tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True&loc=Local",
    m.Host, m.Port, m.Database)
dsn = fmt.Sprintf("%s:%s@%s", m.User, m.Password, dsn)
db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
if err != nil {
    // error handling 
}
m.DB = db

Time zone

Java

Set the JDBC time zone by setting URL parameters:

jdbc:mysql://127.0.0.1:4002?connectionTimeZone=Asia/Shanghai&forceConnectionTimeZoneToSession=true

• connectionTimeZone={LOCAL|SERVER|user-defined-time-zone} specifies the connection time zone.
• forceConnectionTimeZoneToSession=true sets the session time_zone variable to the value specified in connectionTimeZone.

Go

Set the time zone in the DSN. For example, set the time zone to Asia/Shanghai:

dsn := fmt.Sprintf("tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True&loc=Local&time_zone=%27Asia%2FShanghai%27",
    m.Host, m.Port, m.Database)

For more information, see the MySQL Driver Documentation.

Raw SQL

It is recommended to use raw SQL to experience the full features of GreptimeDB. The following example shows how to use raw SQL to query data.

Java

try (Connection conn = getConnection()) {
  Statement statement = conn.createStatement();

  // DESC table;
  ResultSet rs = statement.executeQuery("DESC cpu_metric");
  LOG.info("Column | Type | Key | Null | Default | Semantic Type ");
  while (rs.next()) {
    LOG.info("{} | {} | {} | {} | {} | {}",
        rs.getString(1),
        rs.getString(2),
        rs.getString(3),
        rs.getString(4),
        rs.getString(5),
        rs.getString(6));
  }

  // SELECT COUNT(*) FROM cpu_metric;
  rs = statement.executeQuery("SELECT COUNT(*) FROM cpu_metric");
  while (rs.next()) {
    LOG.info("Count: {}", rs.getInt(1));
  }

  // SELECT * FROM cpu_metric ORDER BY ts DESC LIMIT 5;
  rs = statement.executeQuery("SELECT * FROM cpu_metric ORDER BY ts DESC LIMIT 5");
  LOG.info("host | ts | cpu_user | cpu_sys");
  while (rs.next()) {
    LOG.info("{} | {} | {} | {}",
        rs.getString("host"),
        rs.getTimestamp("ts"),
        rs.getDouble("cpu_user"),
        rs.getDouble("cpu_sys"));
  }
}

For the complete code of the demo, please refer to here.

Go

The following code declares a GORM object model:

type CpuMetric struct {
    Host        string    `gorm:"column:host;primaryKey"`
    Ts          time.Time `gorm:"column:ts;primaryKey"`
    CpuUser     float64   `gorm:"column:cpu_user"`
    CpuSys      float64   `gorm:"column:cpu_sys"`
}

If you are using the High-level API to insert data, you can declare the model with both GORM and GreptimeDB tags.

type CpuMetric struct {
    Host        string    `gorm:"column:host;primaryKey" greptime:"tag;column:host;type:string"`
    Ts          time.Time `gorm:"column:ts;primaryKey"   greptime:"timestamp;column:ts;type:timestamp;precision:millisecond"`
    CpuUser     float64   `gorm:"column:cpu_user"        greptime:"field;column:cpu_user;type:float64"`
    CpuSys      float64   `gorm:"column:cpu_sys"         greptime:"field;column:cpu_sys;type:float64"`
}

Declare the table name as follows:

func (CpuMetric) TableName() string {
  return "cpu_metric"
}

Use raw SQL to query data:

var cpuMetric CpuMetric
db.Raw("SELECT * FROM cpu_metric LIMIT 10").Scan(&result)

Query library reference

For more information about how to use the query library, please see the documentation of the corresponding library:

Java

• JDBC Online Tutorials

Go

• GORM

Command line tools

MySQL

You can use the mysql command line tool to connect to the GreptimeDB. Please refer to the MySQL protocol document for connection information.

After you connect to the server, you can use all GreptimeDB SQL commands to interact with the database.

PostgreSQL

You can use the psql command line tool to connect to the GreptimeDB. Please refer to the PostgreSQL protocol document for connection information.

After you connect to the server, you can use all GreptimeDB SQL commands to interact with the database.

GreptimeDB Dashboard

You can run SQL and visualize data in the GreptimeDB Dashboard.

GUI tools

DBeaver

Please refer to the DBeaver Integration Guide.

HTTP API

You can POST SQL queries to the GreptimeDB HTTP API to query data. Please refer to the HTTP API document for more information.