FAQ

This error indicates a network connectivity problem between your client and the SelectDB instance. If your client and SelectDB instance are in the same Virtual Private Cloud (VPC) and SelectDB

1. From your client machine, use the ping command to ping the VPC address of the SelectDB instance. Check for network connectivity between your machine and the SelectDB instance, or use the telnet command to check if database ports 9030 and 8080 are reachable.

2. Ensure your client's IP address is in the SelectDB whitelist. If not, see Configure a whitelist.

3. Verify that the client IP address configured in the SelectDB whitelist is correct.

   An office network's public IP address can change frequently. The IP address you see may not be the actual public IP. Use an IP lookup service, such as whatsmyip, to confirm your public IP address.

If your SelectDB instance and client are in different VPCs, you must connect over the internet. Follow these steps:

1. Apply for a public endpoint for the SelectDB instance. For instructions, see Apply for or release a public endpoint.

2. Add your client's IP address to the SelectDB whitelist. For instructions, see Configure a whitelist.

   Note

   An office network's public IP address can change frequently. The IP address you see may not be the actual public IP. Use an IP lookup service, such as whatsmyip, to confirm your public IP address.

3. Connect to the cluster. For instructions, see Connect to an instance.

Common causes and solutions are listed below:

• Cause 1: The target data source and the SelectDB instance are in different VPCs, and there is no network connectivity between them.

  Solution: Resolve the network connectivity issue between the target data source and the SelectDB instance. For more information, see How do I resolve network connectivity issues between a SelectDB instance and a data source?.

• Cause 2: The data source's IP address is not in the SelectDB whitelist.

  Solution: Obtain the IP address of the data source and add it to the SelectDB whitelist. For instructions, see Configure a whitelist.

  Note

  An office network's public IP address can change frequently. The IP address you see may not be the actual public IP. Use an IP lookup service, such as whatsmyip, to confirm your public IP address.

• Cause 3: The target data source, such as MySQL or HDFS, has its own whitelist configured.

  Solution: Obtain the IP address of your SelectDB instance and add it to the whitelist of the target data source.

  • To get the IP range of the VPC where your SelectDB instance resides, see How do I find the IP CIDR block of the VPC where my ApsaraDB for SelectDB instance is located?

  • To get the public IP address of your SelectDB instance, use the ping command on its public endpointSelectDB.

If your SelectDB instance and the data source are in the same VPC and region, check whether each has the other's IP address added to its whitelist. If not, add the required IP addresses. For instructions, see Configure a whitelist.

If your SelectDB instance and the data source do not meet the preceding conditions, you must choose a suitable networking solution to establish connectivity before you configure the whitelists.

Common causes and solutions are listed below:

• Cause 1: The network environment is incorrect. Use an internal connection if the application and the instance are in the same VPC. Otherwise, you must apply for a public endpoint and connect over the internet.

  Solution: Check if your application and SelectDB instance are in the same VPC. If they are not, use a public endpoint to connect to the instance. For instructions on how to apply for a public endpoint, see Apply for or release a public endpoint.

• Cause 2: The whitelist is not configured.

  Solution: Add the IP address of the application server to the whitelist of the SelectDB instance. For instructions, see Configure a whitelist.

• Cause 3: The security group rules for the ECS instance where the application is running do not allow traffic.

  Solution: Configure the security group to allow traffic. For more information, see Security group operations.

• Cause 4: A corporate firewall is blocking the connection.

  Solution: Modify the firewall rules to allow the connection.

• Cause 5: The username or password in the connection string contains special characters such as !@#$%^&*()_+=. These characters can cause connection failures if not escaped.

  Solution: Escape special characters in the connection string by using the following rules.

  ! : %21
  @ : %40
  # : %23
  $ : %24
  % : %25
  ^ : %5e
  & : %26
  * : %2a
  ( : %28
  ) : %29
  _ : %5f
  + : %2b
  = : %3d

  For example, if the password is ab@#c, the password in the connection string becomes ab%40%23c after the special characters are escaped.

• Cause 6: Your account has an overdue payment. An overdue payment locks your instance, making it inaccessible.

  Solution: Check if your Alibaba Cloud account has an overdue payment. If it does, complete the payment immediately. For more information about how to check your account balance, see What is a funding account?.

You can use the following common methods:

• Read data by using JDBC: Because SelectDB is compatible with the MySQL protocol, you can use JDBC to read data from SelectDB, similar to how you read data from MySQL. This method is suitable for small datasets (such as tables within tens of GB) because it is simple and easy to implement.

• Read data by using the Flink Doris Connector: The Flink Doris Connector can connect directly to the BE nodes of a SelectDB instance for high-efficiency data reading. For security reasons, you must contact SelectDB technical support to request the required access permissions.

SelectDB does not currently support data backup and restoration from the console. Use the following methods instead.

After you connect to your instance, run the following command to view the BE nodes:

SHOW backends;

BE nodes are fully managed. You do not need to add or manage them after you purchase a SelectDB instance.