ActiveRecord sample application for OceanBase Cloud

This topic describes how to use ActiveRecord and OceanBase Cloud to build an application that can perform basic operations such as creating tables, inserting data, and querying data.

Prerequisites

• You have installed Ruby and RubyGems.
• You have registered an OceanBase Cloud account and created an instance and a MySQL compatible tenant. For more information, see Create an instance and Create a tenant.

Procedure

1. Check the versions of Ruby and RubyGems.
2. Install the required gem.
3. Obtain the connection information of OceanBase Cloud.
4. Create and configure a Rails application.
5. Run the sample application.

Step 1: Check the versions of Ruby and RubyGems

Open the terminal and run the following command to check the versions of Ruby and RubyGems:

ruby -v
gem -v

Step 2: Install the required gem

1. Install the system dependencies (Ubuntu is used as an example):

   sudo apt-get install ruby-dev mysql-client libmysqlclient-dev
   

2. If you use RVM (Ruby Version Manager):

   rvm requirements
   

3. If you use rbenv:

   rbenv install -l  # View available versions
   rbenv install x.x.x  # Install a specific version
   rbenv global x.x.x  # Set the global version
   

4. Use gem to install ActiveRecord and mysql2:

   gem install activerecord mysql2
   

Step 3: Obtain the connection information of OceanBase Cloud

1. Log in to the OceanBase Cloud console. On the instance list page, expand the information of the target instance, and in the target tenant, choose Connect > Get Connection String.

   For more information, see Get the connection string.

2. Fill in the URL with the information of the created OceanBase Cloud database.

   mysql -h$host -P$port -u$user_name -p$password -D$database_name
   

   Parameter description:

   • $host: the connection address of the OceanBase Cloud database, for example, t********.********.oceanbase.cloud.
   • $port: the connection port of the OceanBase Cloud database. The default value is 3306.
   • $database_name: the name of the database to be accessed.
   • $user_name: the account for accessing the database.
   • $password: the password of the account.

Step 4: Create and configure a Rails application

1. Create a new Rails application:

   rails new activerecord_oceanbase -d mysql
   

2. Configure the database connection information:

   Add the following configuration to config/database.yml:

   development:
     adapter: mysql2
     encoding: utf8mb4
     database: your_database
     username: your_username
     password: your_password
     host: your_host
     port: your_port
   

3. Create a sample model:

   # app/models/user.rb
   class User < ActiveRecord::Base
     validates :name, presence: true
   end
   

Step 5: Run the sample application

1. Create a database table:

   # db/migrate/20230520_create_users.rb
   class CreateUsers < ActiveRecord::Migration[6.1]
     def change
       create_table :users do |t|
         t.string :name
         t.timestamps
       end
     end
   end
   

2. Run the migration:

   rails db:migrate
   

3. Test in the Rails console:

   rails c
   

   # Create a record
   user = User.create(name: "John Doe")
   

   # Query records
   users = User.all
   

Common issues

1. Connection error: If you cannot connect to the database, check the following:

   • Whether the database address and port are correct
   • Whether the username and password are correct
   • Whether the network connection is normal

2. Permission error: If you encounter permission-related errors, make sure the user has sufficient permissions to perform the required operations.

3. SQL syntax error: If there is a syntax error in the SQL statement, check whether the syntax of the SQL statement is correct.

Performance optimization recommendations

1. Use ActiveRecord's batch operation methods (such as insert_all)
2. Use eager loading (preload) to avoid N+1 query issues
3. Use caching reasonably
4. Optimize database indexes