This topic provides answers to frequently asked questions (FAQ) about ApsaraDB for SelectDB.
Instance selection
Billing rules
Why are pay-as-you-go bills generated for a subscription instance?
Scenarios
Instance connection
Other
Compared with self-managed Apache Doris databases, what are the advantages of SelectDB instances?
ApsaraDB for SelectDB has the following benefits:
SelectDB supports compute-storage separation and shared storage for multiple clusters, which can reduce storage costs by up to 90%.
SelectDB supports hot and cold-tiered storage based on cache and Object Storage Service (OSS). Data can be stored at a low cost.
You need to configure only backend (BE) clusters. This frees you from the cost of frontend (FE) resources, and the investment cost is lower.
ApsaraDB for SelectDB is an out-of-the-box cloud service. You can use a visualized management platform and API operations to deploy the service and perform O&M operations with ease, or implement automated deployment and O&M. This improves the O&M efficiency.
ApsaraDB for SelectDB provides visualized and easy-to-use data development and management features, such as the SQL editor, retrieval and analysis, query and audit, session management, and metadata management, to reduce your workloads.
SelectDB requires only a small number of O&M staff.
SelectDB is a commercial version that is developed based on the kernel of Apache Doris. Compared with Apache Doris, SelectDB is designed based on a cloud architecture and is deeply optimized. SelectDB provides mature and stable services with professional support from both Alibaba Cloud and SelectDB.
Compared with Apache Doris, what are the advantages of multiple compute clusters in SelectDB?
An ApsaraDB for SelectDB instance can contain multiple compute clusters. Each compute cluster contains one or more BE nodes. A compute cluster is similar to a computing resource group or a compute queue in a big data system. Multiple compute clusters in the same instance have the following features:
Data sharing: Multiple clusters share the underlying data storage and can access the underlying data. This prevents redundant data storage.
Compute-storage separation: The computing resources of multiple clusters are physically isolated. You can use these clusters to isolate different workloads. The cache is also isolated among multiple clusters. Data is cached based on access characteristics.
Simultaneous data reads and writes: Read and write operations are performed in parallel in multiple clusters. After data is written, the written data can be immediately queried in all clusters.
Based on the preceding features, multiple compute clusters are commonly used in scenarios where you need to isolate data reads from data writes, isolate online data analysis from offline data analysis, or isolate the production environment from the test environment.
Why are pay-as-you-go bills generated for a subscription instance?
When you create a subscription ApsaraDB for SelectDB instance, you pay for the first subscription cluster by default. When you use the instance, the generated data occupies storage resources and the occupied storage space is changeable. By default, you are charged for the storage resources that you use based on the pay-as-you-go billing method. In addition, you can create pay-as-you-go clusters in the subscription instance. Therefore, pay-as-you-go bills are generated for pay-as-you-go storage resources and pay-as-you-go clusters.
What scenarios can SelectDB be used in?
ApsaraDB for SelectDB can be used in the following scenarios:
Real-time report analysis
Ad hoc multidimensional analysis
Log retrieval and analysis
Data lakehouse-based analysis
Does SelectDB support triggers?
No, ApsaraDB for SelectDB does not support triggers.
What do I do if the "Can't connect to MySQL server/connect timed out" error message appears when I connect a client to a cluster of my SelectDB instance?
If the "Can't connect to MySQL server/connect timed out" error message appears when you use a client to connect to a cluster of your SelectDB instance, the connection between the server of the client and the SelectDB instance may fail. If the SelectDB instance and the server of the client reside in the same virtual private cloud (VPC) and the same region, you can perform the following steps to troubleshoot the issue:
Run the
pingcommand on the server of the client to ping the IP address of the SelectDB instance in the VPC. Check whether the server of the client and the SelectDB instance are connected. Alternatively, run thetelnetcommand to check whether the 9030 and 8080 database ports are connected.Check whether the IP address of the server of the client is added to the IP address whitelist of the SelectDB instance. If the IP address of the server is not added to the IP address whitelist of the SelectDB instance, you must add the IP address to the IP address whitelist of the SelectDB instance. For more information, see Configure an IP address whitelist.
Check whether the IP address of the server of the client in the IP address whitelist of the SelectDB instance is valid.
On the internal networks of enterprises, the IP addresses of servers are frequently changed. The server IP address that you obtain may not be the actual IP address. You can use an IP address checking tool such as WhatsMyIP to obtain the actual IP address. For more information, see WhatsMyIP.
If the SelectDB instance and the server of the client reside in different VPCs, you must perform the following steps to connect the client to the instance over the Internet:
Apply for a public endpoint for the SelectDB instance. For more information, see Apply for or release a public endpoint.
Add the IP address of the server of the client to the IP address whitelist of the SelectDB instance. For more information about how to configure an IP address whitelist, see Configure an IP address whitelist.
On the internal networks of enterprises, the IP addresses of servers are frequently changed. The server IP address that you obtain may not be the actual IP address. You can use an IP address checking tool such as WhatsMyIP to obtain the actual IP address. For more information, see WhatsMyIP.
Connect to a cluster. For more information, see Connect to an instance.
Why am I unable to connect catalogs pointed to data sources such as MySQL and storage services such as HDFS of a data source?
The following list describes the causes and solutions:
Cause 1: The data source or storage service and the SelectDB instance reside in different VPCs and cannot be connected.
Solution: Resolve the issue based on the instructions provided in What do I do if a connection fails to be established between my SelectDB instance and a data source?SelectDB
Cause 2: The IP address of the data source or storage service is not added to the IP address whitelist of the SelectDB instance.
Solution: Obtain the IP address of the data source or storage service and add the IP address to the IP address whitelist of the SelectDB instance. For more information about how to configure an IP address whitelist, see Configure an IP address whitelist.
On the internal networks of enterprises, the IP addresses of servers are frequently changed. The server IP address that you obtain may not be the actual IP address. You can use an IP address checking tool such as WhatsMyIP to obtain the actual IP address. For more information, see WhatsMyIP.
Cause 3: The IP address whitelist mechanism is enabled for data sources such as MySQL and storage services such as Hadoop Distributed File System (HDFS) of a data source.
Solution: Obtain the IP address of the SelectDB instance and add the IP address to the IP address whitelist of the required data source or storage service.
To obtain the IP address of the SelectDB instance in the VPC to which the SelectDB instance belongs, you can perform the operations provided in How do I view the IP addresses in the VPC to which my ApsaraDB SelectDB instance belongs?
To obtain the public IP address of the SelectDB instance, you can run the ping command to access the public endpoint of the SelectDB instance and obtain the IP address of the instance.
What do I do if a connection fails to be established between my SelectDB instance and a data source?
If the SelectDB instance and the database reside in the same VPC and the same region, check whether the IP address of the SelectDB instance is added to the IP address whitelist of the data source and whether the IP address of the data source is added to the IP address whitelist of the SelectDB instance. If the IP address of the SelectDB instance is not added to the IP address whitelist of the data source and the IP address of the data source is not added to the IP address whitelist of the SelectDB instance, you must add the IP addresses to the corresponding IP address whitelists. For more information, see Configure an IP address whitelist.
If the SelectDB instance and the data source reside in different VPCs, you must select an appropriate network solution. Then, add the IP address of the SelectDB instance to the IP address whitelist of the data source and the IP address of the data source to the IP address whitelist of the SelectDB instance.
Scenario | Solution |
Scenario | Solution |
Connectivity between on-premise data centers and Alibaba Cloud | |
VPC-to-VPC communication across Alibaba Cloud accounts | |
VPC-to-VPC communication across regions and Alibaba Cloud accounts | |
Communication between different VPCs in the same region | Use Basic Edition transit routers to connect VPCs in the same region |
Communication between different VPCs | |
Communication over the Internet | Use the SNAT feature of an Internet NAT gateway to access the Internet |
How do I view the IP addresses in the VPC to which my SelectDB instance belongs?
In ApsaraDB for SelectDB, the IPv4 CIDR block of the vSwitch in which the SelectDB instance resides is the CIDR block of the instance. You can perform the following steps to obtain the CIDR block:
Obtain the vSwitch ID of the instance.
Log on to the SelectDB console.
In the left-side navigation pane, click Instances. On the page that appears, find your instance and click the instance ID.
In the Network Information section of the Instance Details page, view the vSwitch ID parameter.
Obtain the IPv4 CIDR block of the vSwitch in which the SelectDB instance resides.
Log on to the VPC console and go to the vSwitch page.
In the top navigation bar, select the same region as the ApsaraDB for SelectDB instance.
In the search box of the page that appears, specify the required vSwitch ID and click the search icon.
In the vSwitch list, view the IPv4 CIDR block of the required vSwitch.
Why does my application fail to connect to an SelectDB instance?
The following list describes the causes and solutions:
Cause 1: The VPC settings or Internet access settings are improper. If your application and the cluster are deployed in the same VPC, you can connect your application to the cluster over an internal network. If your application and the cluster are deployed in different VPCs, apply for a public endpoint for the cluster.
Solution: Check whether the application and the SelectDB instance reside in the same VPC. If the application and the SelectDB instance reside in different VPCs, you must use the public endpoint to connect to the instance. For more information, see Apply for or release a public endpoint.
Cause 2: The IP address of your application is not added to the whitelist of the cluster.
Solution: Add the IP address of the server of the application to the IP address whitelist of the SelectDB instance. For more information, see Configure an IP address whitelist.
Cause 3: The security group of the Elastic Compute Service (ECS) instance on which the application runs denies access traffic.
Solution: Enable the security group of the ECS instance on which the application runs to allow access traffic. For more information, see Work with security groups.
Cause 4: Your enterprise uses a network firewall.
Solution: Modify the firewall rules.
Cause 5: The account password in the connection string contains any of the following special characters:
!@#$%^&*()_+=. These special characters cannot be recognized during a connection. As a result, the application fails to connect to the instance.Solution: Escape special characters in the connection string by using the following escape rules:
! : %21 @ : %40 # : %23 $ : %24 % : %25 ^ : %5e & : %26 * : %2a ( : %28 ) : %29 _ : %5f + : %2b = : %3dFor example, if the password is
ab@#c, the escaped characters of the password areab%40%23cin the connection string.Cause 6: If your account has an overdue payment, your SelectDB instance is locked and cannot be accessed.
Solution: Check whether your Alibaba Cloud account has an overdue payment. If an overdue payment exists, pay off the overdue payment at your earliest opportunity.
