Preparations

Before connecting to your DDM instance or schema, you have to obtain the connection address of your DDM instance or schema.

Obtaining the Instance Connection Address

1. Log in to the management console.
2. Click Service List and choose Database > Distributed Database Middleware.
3. In the navigation pane, choose Instances. In the instance list, locate the required instance and click its name.
4. In the Network Information area, view the connection address.
   Figure 1 Connection address
   
   

   If you enter an incorrect password too many times when attempting to access your DDM instance, the system will be locked for 20 minutes.

Obtaining the Schema Connection Address

1. Log in to the management console.
2. Choose Service List > Database > Distributed Database Middleware.
3. In the navigation pane, choose Instances. In the instance list, locate the required DDM instance and click its name.
4. In the navigation pane, choose Schemas.
5. In the schema list, locate the required schema and click its name.
6. At the Connection Address area, view the CLI and JDBC connection addresses.
   Figure 2 Schema connection address
   
   

   If you enter an incorrect password for five times or more when attempting to access your DDM instance, the system will be locked for 20 minutes.

Connection Methods

For details about method 1, see Using Navicat to Connect to a DDM Instance.

For details about method 2, see Using the MySQL CLI to Connect to a Schema.

For details about method 3, see Using a JDBC Driver to Connect to a Schema.

For details about method 4, see Using the Console to Connect to a DDM Instance.

Using Navicat to Connect to a DDM Instance

1. Log in to the DDM console, locate the required DDM instance, and click its name.
2. In the Instance Information area, click Bind and select an EIP you have bought.
3. In the left pane, click the VPC icon and choose Access Control > Security Groups.
4. On the Security Groups page, locate the required security group and click Manage Rule in the Operation column. On the displayed page, click Add Rule. Configure the security group rule as required and click OK.
   

   • After binding an EIP to your DDM instance, set strict inbound and outbound rules for the security group to enhance database security.

5. Open Navicat and click Connection. In the displayed dialog box, enter the host IP address (EIP), username, and password (DDM account and password).
6. Click Test Connection. If a message is returned indicating that the connection is successful, click OK. The connection will succeed 1 to 2 minutes later. If the connection fails, the failure cause is displayed. Modify the required information and try again.

Using Navicat to connect to a DDM instance is similar to using other visualized MySQL tools such as MySQL Workbench. Therefore, the procedure of using other visualized MySQL tools to connect to a DDM instance has been omitted.

Using the MySQL CLI to Connect to a Schema

1. Log in to the required ECS, open the CLI, and run the following command:

   mysql -h ${DDM_SERVER_ADDRESS} -P${DDM_SERVER_PORT} -u${DDM_USER} -p [-D${DDM_DBNAME}] [--default-character-set=utf8]

   Table 1 Parameter description

   Example Parameter	Description	Example Value
   DDM_SERVER_ADDRESS	IP address of the DDM instance	192.168.0.200
   DDM_SERVER_PORT	Connection port of the DDM instance	5066
   DDM_USER	Account of the DDM instance	dbuser01
   DDM_DBNAME	(Optional) Name of the target schema in the DDM instance	-
   default-character-set=utf8	(Optional) UTF-8 character set Configure this parameter if garbled characters are displayed during parsing due to inconsistency between MySQL connection code and actually used code.	-

2. View the command output. The following is an example output of running a MySQL command in the Windows CLI.

   C:\Users\testDDM>mysql -h192.168.0.200 -P5066 -Ddb_5133 -udbuser01 -p
   Enter password:
   Reading table information for completion of table and column names
   You can turn off this feature to get a quicker startup with -A
    
   Welcome to the MySQL monitor.  Commands end with ;or \g.
   Your MySQL connection id is 5
   Server version: 5.6.29
    
   Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
    
   Oracle is a registered trademark of Oracle Corporation and/or its
   affiliates. Other names may be trademarks of their respective
   owners.
    
   Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
    
   mysql>

Using a JDBC Driver to Connect to a Schema

This section uses the SQL query statement as an example to describe how to connect to a DDM instance.

1. Load the required JDBC driver.

   Class.forname(com.mysql.jdbc.Driver);

   

   JDBC drivers 5.1.35 to 5.1.45 are recommended.

2. Create a database connection.

   String username = "dbuser01" ;
   String password = "xxxxxx" ; 
   String url = "jdbc:mysql://192.168.0.200:5066/db_5133";
   Connection con = DriverManager.getConnection(url , username , password);

3. Create a Statement object.

   Statement stmt = con.createStatement();

4. Execute the required SQL statement.

   ResultSet rs = stmt.executeQuery("select now() as Systemtime");
   con.close();

5. (Optional) Optimize code as needed.

   loadBalanceAutoCommitStatementThreshold=5&loadBalanceHostRemovalGracePeriod=15000&loadBalanceBlacklistTimeout=60000&loadBalancePingTimeout=5000&retriesAllDown=10&connectTimeout=10000";

   

   • loadBalanceAutoCommitStatementThreshold and retriesAllDown parameters must be configured based on the example in 5. Otherwise, an infinite loop may occur during the connection switchover, resulting in stack overflow.
   • loadBalanceAutoCommitStatementThreshold: defines the number of matching statements which will trigger the driver to potentially swap physical server connections.
   • loadBalanceHostRemovalGracePeriod: indicates the grace period to wait for a host being removed from a load-balanced connection, to be released when it is the active host.
   • loadBalanceBlacklistTimeout: indicates the time in milliseconds between checks of servers which are unavailable, by controlling how long a server lives in the global blacklist.
   • loadBalancePingTimeout: indicates the time in milliseconds that the connection will wait for a response to a ping operation when you set loadBalanceValidateConnectionOnSwapServer to true.
   • retriesAllDown: indicates the maximum number of connection attempts before an exception is thrown when a valid host is searched. SQLException will be returned if the threshold of retries is reached with no valid connections obtained.
   • connectTimeout: indicates the maximum amount of time in milliseconds that the JDBC driver is willing to wait to set up a socket connection. 0 indicates that the connection does not time out. Only JDK-1.4 or later is supported. The default value 0.

Using the Console to Connect to a DDM Instance

1. Log in to the DDM console.
2. In the navigation pane, choose Instances.
3. In the instance list, locate the required instance and click Log In in the Operation column.
   On the displayed page, enter the required username and password.

   Figure 3 Login page
   

4. On the displayed page, enter the account created in Step 5: Create a DDM Account.
5. Click Test Connection.
6. (Optional) Enable Collect Metadata Periodically and Show Executed SQL Statements.
7. Ensure that all settings are correct and click Log In.