This topic describes how to synchronize data from an ApsaraDB RDS for PostgreSQL instance to an AnalyticDB for PostgreSQL instance by using Data Transmission Service (DTS). The data synchronization feature provided by DTS allows you to transfer and analyze data with ease.
- The tables to be synchronized from the ApsaraDB RDS for PostgreSQL instance must contain primary keys.
- The destination AnalyticDB for PostgreSQL instance is created. For more information, see Create an AnalyticDB for PostgreSQL instance.
- A data synchronization task can synchronize data from only one database. To synchronize data from multiple databases, you must create a data synchronization task for each database.
- During data synchronization, new tables that are created in the source database can also be synchronized. However, to ensure data consistency, you must execute the following statement on the new tables before they can be synchronized:
ALTER TABLE schema.table REPLICA IDENTITY FULL;
- To ensure that the data synchronization task runs as expected, you can perform primary/secondary switchover only on an ApsaraDB RDS for PostgreSQL 11 instance. In this case, you must set the
sync. For more information, see Logical Replication Slot Failover.Warning If you perform primary/secondary switchover on a self-managed PostgreSQL database or an ApsaraDB RDS for PostgreSQL instance of other versions, the data synchronization task stops.
- If the source database has long-running transactions and the task contains incremental data synchronization, the write-ahead logging (WAL) logs before the long-running transactions are submitted may not be cleared and therefore pile up, resulting in insufficient storage space in the source database.
|Synchronization type||Task configuration fee|
|Schema synchronization and full data synchronization||Free of charge.|
|Incremental data synchronization||Charged. For more information, see Billing overview.|
- Schema synchronization is not supported. DTS does not synchronize the schemas of objects from the source database to the destination database.
- You can select only tables as the objects to be synchronized.
- DTS does not synchronize the following types of data: BIT, VARBIT, GEOMETRY, UUID, TSQUERY, TSVECTOR, and TXID_SNAPSHOT.
- If you perform a DDL operation on an object to be synchronized in the source database during data synchronization, you must perform the operation in the destination database. Then, you must restart the data synchronization task.
SQL statements that can be synchronized
INSERT, UPDATE, and DELETE
- Change the value of the
wal_levelparameter for the source ApsaraDB RDS instance.Warning After you change the value of the
wal_levelparameter, you must restart the instance to apply the change. We recommend that you evaluate the impact on your business and change the parameter settings during off-peak hours.
- Log on to the ApsaraDB RDS console.
- In the top navigation bar, select the region in which the ApsaraDB RDS instance resides.
- Find the ApsaraDB RDS instance and click the instance ID.
- In the left-side navigation pane, click Parameters.
- On the Parameters page, find the
wal_levelparameter and change the parameter value to
- Create a database, schema, and table in the destination AnalyticDB for PostgreSQL instance based on the schema of the objects to be synchronized in the source ApsaraDB RDS instance. For more information, see SQL statements.
- Purchase a data synchronization instance. For more information, see Purchase a DTS instance. Note On the buy page, set Source Instance to PostgreSQL, set Destination Instance to AnalyticDB for PostgreSQL, and set Synchronization Topology to One-Way Synchronization.
- Log on to the DTS console.
- In the left-side navigation pane, click Data Synchronization.
- At the top of the Synchronization Tasks page, select the region where the destination instance resides.
- Find the data synchronization instance and click Configure Synchronization Channel in the Actions column.
- Configure the source and destination instances.
Section Parameter Description N/A Task Name The task name that DTS automatically generates. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to use a unique task name. Source Database Instance Type The type of the source instance, Select RDS Instance. Instance Region The source region that you selected on the buy page. You cannot change the value of this parameter. Instance ID The ID of the ApsaraDB RDS for PostgreSQL instance. Database Name The name of the source database. Database Account The privileged account of the ApsaraDB RDS for PostgreSQL instance. The account must be the owner of the selected database.Note If the source database runs on an ApsaraDB RDS for PostgreSQL 9.4 instanceand you synchronize only DML operations, only the REPLICATION permission is required for the database account. Database Password The password of the database account. Destination Database Instance Type The value of this parameter is fixed to AnalyticDB for PostgreSQL. Instance Region The destination region that you selected on the buy page. The value of this parameter cannot be changed. Instance ID The ID of the destination AnalyticDB for PostgreSQL instance. Database Name The name of the destination database.Note The database must exist in the AnalyticDB for PostgreSQL instance. Otherwise, you must create a database. Database Account The initial account of the AnalyticDB for PostgreSQL instance. For more information, see Create a database account.Note You can also enter an account that has the RDS_SUPERUSER permissions. For more information, see Manage users and permissions. Database Password The password of the database account.
- In the lower-right corner of the page, click Set Whitelist and Next. Note
- You do not need to modify the security settings for ApsaraDB instances (such as ApsaraDB RDS for MySQL and ApsaraDB for MongoDB) and ECS-hosted databases. DTS automatically adds the CIDR blocks of DTS servers to the whitelists of ApsaraDB instances or the security group rules of Elastic Compute Service (ECS) instances. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.
- After data synchronization is complete, we recommend that you remove the CIDR blocks of DTS servers from the whitelists or security groups.
- Configure the synchronization policy and the objects to be synchronized.
Section Parameter Description Set the synchronization policy Initial Synchronization By default, Initial Full Data Synchronization is selected. After the precheck, DTS synchronizes historical data of the required objects from the source database to the destination instance. The data is the basis for subsequent incremental synchronization. Processing Mode of Conflicting Tables
- Clear Data
Skip the check for empty destination tables during the precheck. Clear the data in destination tables before the full data synchronization task is initialized. If you want to synchronize your business data after testing the data synchronization task, you can select this mode.
Skip the check for empty destination tables during the precheck. Add data to the existing data during initial full data synchronization. If you want to synchronize data from multiple tables to one table, you can select this mode.
Select the types of operations that you want to synchronize based on your business requirements.Note The Alter Table operation is not supported.
Select objects to be synchronized N/A
Select one or more tables from the Available section and click the icon to add the tables to the Selected section.Note
- You can select only tables as objects to be synchronized.
- You can use the object name mapping feature to rename the columns that are synchronized to the destination database. For more information, see Rename an object to be synchronized.
Rename Databases and Tables N/A
You can use the object name mapping feature to rename the objects that are synchronized to the destination instance. For more information, see Object name mapping.
Retry Time for Failed Connections N/ABy default, if DTS fails to connect to the source or destination database, DTS retries within the next 720 minutes (12 hours). You can specify the retry time based on your needs. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails.Note When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
- Clear Data
- In the lower-right corner of the page, click Precheck. Note
- Before you can start the data synchronization task, DTS performs a precheck. You can start the data synchronization task only after the task passes the precheck.
- If the task fails to pass the precheck, click the icon next to each failed item to view details.
- After you troubleshoot the issues based on the causes, run a precheck again.
- If you do not need to troubleshoot the issues, ignore failed items and run a precheck again.
- Close the Precheck dialog box after the following message is displayed: The precheck is passed. Then, the data synchronization task starts.
- Wait until initial synchronization is completed and the data synchronization task enters the Synchronizing state. You can view the state of the data synchronization task on the Synchronization Tasks page.