Data Transmission Service

1. Does DTS support data migration between RDS instances under two different Alibaba Cloud accounts?

Yes. When migrating data between RDS instances under different Alibaba Cloud accounts, you need to login DTS console with the account of the target RDS instance.
When configuring the migration task, you need to select on-permit databases with public IP addresses for the source instance,and configure the connection of the source RDS instance.

2. Does DTS support migrating the change data of the source instance during data migration?

Yes. All data changes to the source database that occur during the migration are continuously replicated to the target. DTS allows the source database to be fully operational during the migration process.

3. What are the basic principles of change data migration through DTS?

The basic principles of change data migration through DTS are described below:
During data migration, DTS starts the log parsing module to capture and parse the change logs of the source database in real time. Then, DTS starts migrating the existing data. After data loading, DTS replicates the captured change data to the target instance, and the target database will remain synchronized with the source for as long as you choose.

4. Are tables locked during data migration through DTS?

When you choose migration existing data and replication change data, during the full data migration, DTS checks whether the source database contains any non-transactional tables having no primary keys (for example, MyISAM). If such tables exist, DTS places read-only locks on the tables to ensure data migration consistency. In other cases, DTS does not place locks on source databases.

5. Which network (intranet or Internet) is used to access ECS instance during data migration through DTS?

If the network type of the ECS instance is VPC, DTS connects to the ECS instance with the Internet.
If the ECS instance is the source instance of the migration task and is located in a region different from the target instance of the migration task, DTS connect to the ECS with the Internet.
Otherwise, DTS connects to the ECS instance with an intranet.

6. Which network (intranet or Internet) is used to access the RDS instance during data migration through DTS?

If the RDS instance is the source instance of the migration task and is located in a region different from the target instance of the migration task, DTS connects to the RDS instance with the Internet.
Otherwise, DTS connects to the RDS instance with intranet.

7. If the RDS instance is the source instance of the migration task and is located in a region different from the target instance of the migration task, DTS can connect to the RDS instance with the Internet. Otherwise, DTS connects to the RDS instance with an intranet.

If database type of the source instance is MySQL or MongoDB, then the DDL operation will be synchronized.
Otherwise, the DDL operation will not be synchronized.

8. Does DTS support migrating the database on a VPC ECS instance to an RDS instance?

Yes, but the ECS instance must be attached with an EIP address. When configuring the migration task, select the ECS instance for the source instance. DTS accesses the ECS instance with the EIP address of the ECS instance.

9. From which database (active/standby) does DTS capture data during data migration?

DTS captures data from the active database of the RDS instance during data migration.

10. Can DTS migrate the database C in the RDS instance A to the database D in the RDS instance B?

Yes. DTS supports database name mapping which allows data migration between two different databases in two RDS instances.

11. Is the data in the source database deleted after migration through DTS?

No. DTS only copies data in the source database during data migration, and thus the data in the source database is not affected.

12. Why have I received the following error: "Failed to obtain the structure object "[java.sql.SQLException: I/O exception: The Network Adapter co" reported?

If such error is reported, DTS fails to connect to the source database. Possible causes include:
(1) The connection address is incorrect.
(2) The firewall is enabled for the local database.
(3) Remote listening is not enabled for the database.

13. What is the table "increment_trx" generated in the target database during data migration?

The table "increment_trx" is created by DTS. It is mainly used to record the checkpoint of migration. When the task is interrupt, DTS automatically restarts the process and continues the migration from the checkpoint recorded.
Do not drop the table; otherwise, the migration task fails.

14. Why is the size of the target RDS instance larger than the source database after migration through DTS.

DTS migrates data through SQL. It will generate binlog in the target instance. Therefore, the size of the target RDS instance after migration is larger than the source database.

15. Why have I received the following error: "java.sql.BatchUpdateException: INSERT, DELETE command denied to user 'user'"?

The general cause is that the target RDS instance is locked, and the write privilege of the account is revoked.
To resolve the problem, you can upgrade the space of the target RDS instance, and restart the task on the DTS Console.

16. Does the data within the tables of the target database overwritten during data migration through DTS?

No. The table of the target instance to be migrated needs to be empty before data migration. If the table to be migrated already exists in the target database, the precheck will fail.

17. How can I migrate a database to the RDS instance from another Alibaba Cloud account.

You will need to log on to the DTS Console from the Alibaba Cloud account of the target RDS instance. Set the source instance type to on-permit database, and configure the connection of the source RDS instance.

18. Does the release of a finished migration task affect the use of the migrated database?

No.

19. Can DTS support the synchronization between on_permit database and the RDS instance?

Yes. You can use DTS to perform synchronization between the cloud instance and the on-permit database.

20. Which network (intranet or Internet) is used during data DTS synchronization?

DTS transfers data with intranet during data synchronization.

21. Why is it that my data subscription SDK cannot subscribe to any message and the prompt "client partition is empty, wait partition balance" is always reported?

Why my data subscription SDK cannot subscribe to any message and the prompt "client partition is empty, wait partition balance" is always reported.

22. Why is "keep alive error" reported at the data subscription SDK?

The consumption timestamp is not in the data range of the data subscription instance. You need to modify the consumption timestamp and restart the SDK.

23. Why does the system report an error: "failed to get master store addr for topic aliyun_sz_ecs_ApsaraDBr*****y-1-0" when I use the data subscription function?

Firstly, check whether the sePublicIp in SDK is set to true.
If usePublicIp = true, check whether the consumption timestamp is within the data range of the subscription instance. If not, modify the consumption timestamp and restart the SDK.

24. Why does the system report an error: "Specified signature is not matched with our calculation. at com.aliyuncs.DefaultAcsClient.parseAcsResponse(DefaultAcsClient.java:139) at" when I start the SDK for data subscription?

The Access Key/Access Secret configured in the SDK does not belong to the Alibaba Cloud account corresponding to the subscription instance. Modify Access Key/Access Secret and restart the SDK.

25. Can an SDK client subscribe to multiple channels?

No.

26.Why does the system report "get guid info failed" when I start SDK subscription?

The subscription instance ID set in the SDK is incorrect. You need to replace the "subscription instance ID in the sample code client with the ID of the subscription instance to which you want to subscribe.