Step 4: Log In to the DDM Schema

Preparations

Obtaining the Schema Connection Address

1. Log in to the DDM console.
2. In the instance list, locate the required DDM instance and click its name.
3. In the navigation pane on the left, choose Schemas. On the displayed page, click View in the Connection Address column.

   Alternatively, locate the target schema, click its name to go to the Basic Information page. In the Connection Address tab page, obtain connection addresses for CLI and JDBC.

   Note

   • If load balancing is enabled, one floating IP address will be assigned to a DDM instance even if it has multiple nodes. You can use this address to connect to the DDM instance for load balancing.
   • There are some historical instances that do not support load balancing, so they have multiple IP addresses. For load balancing, you can use JDBC connection strings to connect to them.
   • If read-only groups are created, each group will be assigned a load balancing address for service isolation.

Connection Methods

Using Navicat to Log In to a DDM Instance

1. Log in to the DDM console, locate the required DDM instance, and click its name.
2. Ask technical support to add an EIP to the feature whitelist. In the Instance Information area, click Bind. In the displayed dialog box, select the EIP and click OK. Bind the EIP with your DDM instance.
3. In the navigation pane on the left, 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 needed and click OK.
   Note

   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).
   Note

   Navicat12 is recommended for Navicat clients.

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 the MySQL CLI to Log In 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][--default_auth=mysql_native_password]
   
   

   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 encoding system Configure this parameter if garbled characters are displayed during parsing due to inconsistency between MySQL connection code and actually used code.	-
   default_auth=mysql_native_password	(Optional) Password authentication plug-in used by default	-

   Note

   • If you use the MySQL 8.0 client, set default_auth to mysql_native_password.

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 Log In to a Schema

1. Load the required JDBC driver.

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

2. Create a database connection.

   String username = "EXAMPLE_USERNAME_ENV" ;
   String password = "EXAMPLE_PASSWORD_ENV" ; 
   String url = "jdbc:mysql://ip:port/db_name";
   Connection con = DriverManager.getConnection(url , username , password);
   
   

   Note

   • There will be security risks if the username and password used for authentication are directly written into code. Store the username and password in ciphertext in the configuration file or environment variables.
   • In this example, the username and password are stored in the environment variables. Before running this example, set environment variables EXAMPLE_USERNAME_ENV and EXAMPLE_PASSWORD_ENV as needed.

   For details, see the example parameter value in Table 2.

   Table 2 URL parameter description

   Parameter	Description	Example Value
   ip:port	Indicates the connection address and port number for connecting to your DDM instance.	192.168.0.200:5066 See Obtaining the Schema Connection Address to obtain the JDBC connection address and port number.
   db_name	Indicates the name of a schema.	db_5505 On the DDM console, locate the required instance and click its name. In the navigation pane on the left, choose Schemas to view the schema name.

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&useSSL=true";
   
   

   Note

   • Parameters loadBalanceAutoCommitStatementThreshold and retriesAllDown must be configured based on the example in 5. Otherwise, an infinite loop may occur during the connection switchover, resulting in stack overflow.
   • For details about parameter configurations, see Table 3.

   Table 3 Parameter description

   Parameter	Description	Example Value
   loadBalanceAutoCommitStatementThreshold	Indicates the number of statements executed before a reconnection. If the parameter value is set to 5, a reconnection is required after five SQL statements (queries or updates) are executed. If it is set to 0, a sticky connection is initiated instead of a reconnection. When automatic submission is disabled (autocommit is set to false), the system waits for the transaction to complete and then determines whether to initiate a reconnection.	5
   loadBalanceHostRemovalGracePeriod	Indicates the grace period to wait for a host being removed from a load balancing connection, and to be released when it is the active host.	15000
   loadBalanceBlacklistTimeout	Indicates the time in milliseconds between checks of servers which are unavailable, by controlling how long a server lives in the global blacklist.	60000
   loadBalancePingTimeout	Indicates the time in milliseconds for waiting for the ping response of each load balancing connection.	5000
   retriesAllDown	Indicates the maximum number of polling retries when all connection addresses fail. SQLException will be returned if the threshold of retries is reached with no valid connections obtained.	10
   connectTimeout	Specifies the timeout interval for establishing a socket connection with a database server. Unit: millisecond. A value of 0 indicates that connection establishment never times out. This parameter setting is used for JDK 1.4 or later versions.	10000
   socketTimeout	Specifies the timeout interval for a socket operation (read and write). Unit: millisecond. A value of 0 indicates that a socket operation never times out.	Set this parameter based on your service requirements.
   useSSL	Indicates that an SSL connection is used to connect to DDM.	true