Connect to OceanBase Database by using Active Record

This topic describes how to build an application by using Active Record and OceanBase Database. It also explains how to perform fundamental database operations, including table creation, data insertion, and data querying.

Prerequisites

• You have installed Ruby and RubyGems.
• You have installed OceanBase Database and created a MySQL-compatible tenant.

Procedure

1. Check the versions of Ruby and RubyGems.
2. Install the necessary gems.
3. Obtain the connection information of OceanBase Database.
4. Create and configure the Rails application.
5. Run the sample application.

Step 1: Check the versions of Ruby and RubyGems

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

ruby -v
gem -v

Step 2: Install the necessary gems

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

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

2. If you are using Ruby Version Manager (RVM):

   rvm requirements
   

3. If you are using 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 Active Record and mysql2:

   gem install activerecord mysql2
   

Step 3: Obtain the connection information of OceanBase Database

Contact the deployment personnel or administrator of OceanBase Database to obtain the database connection string.

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

Parameter description:

• $host: the IP address for connecting to OceanBase Database.
• $port: the port for connecting to OceanBase Database.
• $database_name: the name of the database to be accessed.
• $user_name: the tenant account.
• $password: the password of the account.

Step 4: Create and configure the 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
   

FAQ

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

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

2. Privilege error: If you encounter a privilege-related error, make sure that the user has sufficient privileges to perform the required operation.

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

Performance optimization suggestions

1. Use batch operation methods of Active Record, such as insert_all.
2. Use preloading to avoid N+1 queries.
3. Use cache properly.
4. Optimize database indexes.