Build a Go application that uses YSQL

The following tutorial shows a small Go application that connects to a YugabyteDB cluster using the Go PostgreSQL driver and performs basic SQL operations. Use the application as a template to get started with YugabyteDB Aeon in Go.

Prerequisites

Go (tested with version 1.17.6).

Clone the application from GitHub

Clone the sample application to your computer:

git clone https://github.com/YugabyteDB-Samples/yugabyte-simple-go-app.git && cd yugabyte-simple-go-app

Provide connection parameters

If your cluster is running on YugabyteDB Aeon, you need to modify the connection parameters so that the application can establish a connection to the YugabyteDB cluster. (You can skip this step if your cluster is running locally and listening on 127.0.0.1:5433.)

To do this:

1. Open the sample-app.go file.

2. Set the following configuration parameter constants:

   • host - the host name of your YugabyteDB cluster. For local clusters, use the default (127.0.0.1). For YugabyteDB Aeon, select your cluster on the Clusters page, and click Settings. The host is displayed under Connection Parameters.
   • port - the port number for the driver to use (the default YugabyteDB YSQL port is 5433).
   • dbName - the name of the database you are connecting to (the default is yugabyte).
   • dbUser and dbPassword - the username and password for the YugabyteDB database. For local clusters, use the defaults (yugabyte and yugabyte). For YugabyteDB Aeon, use the credentials in the credentials file you downloaded.
   • sslMode - the SSL mode to use. YugabyteDB Aeon requires SSL connections; use verify-full.
   • sslRootCert - the full path to the YugabyteDB Aeon cluster CA certificate.

3. Save the file.

Build and run the application

First, initialize the GO111MODULE variable.

$ export GO111MODULE=auto

Import the Go PostgreSQL driver.

$ go get github.com/lib/pq

Start the application.

$ go run sample-app.go

You should see output similar to the following:

>>>> Successfully connected to YugabyteDB!
>>>> Successfully created table DemoAccount.
>>>> Selecting accounts:
name = Jessica, age = 28, country = USA, balance = 10000
name = John, age = 28, country = Canada, balance = 9000
>>>> Transferred 800 between accounts.
>>>> Selecting accounts:
name = Jessica, age = 28, country = USA, balance = 9200
name = John, age = 28, country = Canada, balance = 9800

You have successfully executed a basic Go application that works with YugabyteDB Aeon.

Explore the application logic

Open the sample-app.go file in the yugabyte-simple-go-app folder to review the methods.

main

The main method establishes a connection with your cluster via the Go PostgreSQL driver.

psqlInfo := fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s",
    host, port, dbUser, dbPassword, dbName)

if sslMode != "" {
    psqlInfo += fmt.Sprintf(" sslmode=%s", sslMode)

    if sslRootCert != "" {
        psqlInfo += fmt.Sprintf(" sslrootcert=%s", sslRootCert)
    }
}

db, err := sql.Open("postgres", psqlInfo)

createDatabase

The createDatabase method uses PostgreSQL-compliant DDL commands to create a sample database.

Statement stmt = conn.createStatement();

stmt := `DROP TABLE IF EXISTS DemoAccount`
_, err := db.Exec(stmt)
checkIfError(err)

stmt = `CREATE TABLE DemoAccount (
                      id int PRIMARY KEY,
                      name varchar,
                      age int,
                      country varchar,
                      balance int)`

_, err = db.Exec(stmt)
checkIfError(err)

stmt = `INSERT INTO DemoAccount VALUES
              (1, 'Jessica', 28, 'USA', 10000),
              (2, 'John', 28, 'Canada', 9000)`

_, err = db.Exec(stmt)
checkIfError(err)

selectAccounts

The selectAccounts method queries your distributed data using the SQL SELECT statement.

rows, err := db.Query("SELECT name, age, country, balance FROM DemoAccount")
checkIfError(err)

defer rows.Close()

var name, country string
var age, balance int

for rows.Next() {
    err = rows.Scan(&name, &age, &country, &balance)
    checkIfError(err)

    fmt.Printf("name = %s, age = %v, country = %s, balance = %v\n",
        name, age, country, balance)
}

transferMoneyBetweenAccounts

The transferMoneyBetweenAccounts method updates your data consistently with distributed transactions.

tx, err := db.Begin()
checkIfError(err)

_, err = tx.Exec(`UPDATE DemoAccount SET balance = balance - $1 WHERE name = 'Jessica'`, amount)
if checkIfTxAborted(err) {
    return
}
_, err = tx.Exec(`UPDATE DemoAccount SET balance = balance + $1 WHERE name = 'John'`, amount)
if checkIfTxAborted(err) {
    return
}

err = tx.Commit()
if checkIfTxAborted(err) {
    return
}

Learn more

Go PostgreSQL driver