Synchronize Db2 for LUW to AnalyticDB for PostgreSQL-AnalyticDB(AnalyticDB)-阿里云帮助中心

Prerequisites

You have created a destination AnalyticDB for PostgreSQL instance. For instructions, see Create an instance.
For a full data synchronization, the destination database must have more storage space than the data in the source database.

Limitations

Note

During schema synchronization, DTS synchronizes foreign keys from the source database to the destination database.
During full data synchronization and incremental data synchronization, DTS temporarily disables constraint checks and foreign key cascade operations at the session level. Data inconsistency may occur if cascade update or delete operations are performed on the source database while the task is running.

Limit type	Description
Limits on the source database	Bandwidth requirements: The server on which the source database is deployed must have sufficient outbound bandwidth. Otherwise, the data synchronization speed decreases. The tables to be synchronized must have PRIMARY KEY or UNIQUE constraints, and all fields must be unique. Otherwise, the destination database may contain duplicate data records. If you select tables as the objects to be synchronized and you want to modify the tables in the destination database, such as renaming tables or columns, you can synchronize up to 5,000 tables in a single data synchronization task. If you run a task to synchronize more than 5,000 tables, a request error occurs. In this case, we recommend that you configure multiple tasks to synchronize the tables in batches or configure a task to synchronize the entire database. The data logging feature must be enabled. Otherwise, error messages are returned during precheck, and the data synchronization task cannot be started. Note If you perform only incremental data synchronization, the data logs of the source database must be stored for more than 24 hours. If you perform both full data synchronization and incremental data synchronization, the data logs of the source database must be stored for at least seven days. Otherwise, DTS may fail to obtain the data logs and the task may fail. In exceptional circumstances, data inconsistency or loss may occur. After full data synchronization is complete, you can set the retention period to more than 24 hours. Make sure that you set the retention period of data logs based on the preceding requirements. Otherwise, the service reliability or performance stated in the SLA of DTS cannot be guaranteed. Do not run DDL operations that change database or table schemas during schema synchronization or full synchronization. Otherwise, the synchronization task fails. Note During full synchronization, DTS queries the source database. This creates metadata locks that may block DDL operations on the source database.
Other limits	DTS synchronizes incremental data from a Db2 for LUW database to the destination database based on the CDC replication technology of Db2 for LUW. However, the CDC replication technology has its own limits. For more information, see General data restrictions for SQL Replication. If the table to synchronize has a primary key, the primary key column in the destination table must match the source table. If the table to synchronize lacks a primary key, the primary key column in the destination table must match the distribution key. The unique key in the destination table—including the primary key column—must include all columns in the distribution key. Before you synchronize data, evaluate the impact of data synchronization on the performance of the source and destination databases. We recommend that you synchronize data during off-peak hours. During initial full data synchronization, DTS uses the read and write resources of the source and destination databases. This may increase the loads on the database servers. During initial full data synchronization, concurrent INSERT operations cause fragmentation in the tables of the destination database. Therefore, after initial full data synchronization is complete, the size of the used tablespace of the destination database is larger than that of the source database. During data synchronization, we recommend that you use only DTS to write data to the destination database. This prevents data inconsistency between the source and destination databases. After data synchronization is complete, you can use DMS to execute DDL statements online. For more information, see Perform lock-free DDL operations. During schema synchronization and incremental data synchronization, the foreign keys of the source database are not synchronized to the destination database. You can select only tables as the objects to be synchronized. The tables cannot be append-optimized (AO) tables. If column mapping is used for non-full table synchronization or if the source and destination table structures are inconsistent, the data in the columns of the source database that are not contained in the destination database will be lost. If a task fails, DTS support staff will attempt to restore it within eight hours. During restoration, they may restart the task or adjust its parameters. Note Only DTS task parameters are modified—not database parameters. Parameters that may be adjusted include those listed in Modify instance parameters.
Special cases	The source Db2 for LUW database is a self-managed database. When you synchronize data from the Db2 for LUW database, take note of the following items: If you perform a primary/secondary switchover on the source database when the data synchronization task is running, the task fails. DTS calculates synchronization latency based on the timestamp of the latest synchronized data record in the destination database and the current timestamp in the source database. If no DML operation is performed on the source database for a long time, the synchronization latency may be inaccurate. If the synchronization latency is too high, you can perform a DML operation on the source database to update the latency. Note If you select an entire database as the object to be synchronized, you can create a heartbeat table. The heartbeat table is updated or receives data every second.

Billing

Synchronization type	Pricing
Schema synchronization and full data synchronization	Free of charge.
Incremental data synchronization	Charged. For more information, see Billing overview.

Synchronization topologies

One-to-one
One-to-many
Cascade
Many-to-one

To learn about these synchronization topologies and when to use them, see Introduction to Synchronization Topologies.

Supported SQL operations

Operation type	SQL statement
DML	INSERT, UPDATE, DELETE Note The system automatically converts UPDATE statements to REPLACE INTO statements when writing data to a destination AnalyticDB for PostgreSQL instance. If an UPDATE statement modifies a primary key, the system instead converts it into a DELETE statement and an INSERT statement.

Prerequisites

Create accounts and grant permissions

Database	Permissions	Actions
Db2 for LUW	DBADM permission	Create User
AnalyticDB for PostgreSQL	Read and write permissions on the target database containing the objects to be synchronized	Create and Manage Users Note You can also use an account that has the RDS_SUPERUSER permission. For instructions on creating the account, see user permission management.

Enable the log archiving feature for the Db2 for LUW database. For more information, see logarchmeth1 - Primary log archive method configuration parameter and logarchmeth2 - Secondary log archive method configuration parameter.

Procedure

Go to the Data Synchronization Tasks page.
1. Log on to the DMS console.
2. In the top navigation bar, click Data + AI.
3. In the left-side navigation pane, choose DTS (DTS) > Data Synchronization.
Note
- Operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode console and Customize the layout and style of the DMS console.
- You can also go to the Data Synchronization Tasks page of the new DTS console.
Click Create Task to open the task configuration page.
Optional: In the upper-right corner of the page, click New Configuration Page.
Note
- If you are already on the new configuration page (the button in the upper-right corner is Back to Previous Version), you can skip this step.
- Some parameters differ between the new and old configuration pages. We recommend using the new version.

Configure the source and destination databases.

Category	Parameter	Description
N/A	Task Name	DTS automatically generates a task name. We recommend that you specify a descriptive name for easy identification. The name does not need to be unique.
Source Database	Select a DMS database instance.	Choose whether to use an existing instance as needed. If you use an existing instance, the database information is automatically filled in. You do not need to enter it again. If you do not use an existing instance, configure the database information below. Note In the DMS console, click Add DMS Database Instance to add a database instance. For more information, see Add an ApsaraDB database instance and Add a third-party or self-managed database instance. In the DTS console, you can add a database to DTS on the Database Connections page or the new configuration page. For more information, see Manage data connections.
	Database Type	Select DB2 for LUW.
	Connection Type	Select an access method based on where your source database is deployed. This topic uses Self-managed Database on ECS as an example. Note If the source instance is a self-hosted database, you must also perform preparatory work. For more information, see Overview of preparations.
	Instance Region	Select the region where the DB2 LUW database resides.
	Replicate Data Across Alibaba Cloud Accounts	For this example, select No, as the database instance belongs to the current Alibaba Cloud account.
	ECS Instance ID	Enter the ID of the ECS instance that hosts the DB2 LUW database.
	Port	Enter the service port of the DB2 LUW database. The default port is 50000.
	Database Name	Enter the name of the database in the source DB2 LUW instance that contains the objects to be synchronized.
	Database Account	Enter the database account of the DB2 LUW database. For information about the required permissions, see Create an account and grant permissions.
	Database Password	Enter the password for the specified database account.
Destination Database	Select a DMS database instance.	Choose whether to use an existing instance as needed. If you use an existing instance, the database information is automatically filled in. You do not need to enter it again. If you do not use an existing instance, configure the database information below. Note In the DMS console, click Add DMS Database Instance to add a database instance. For more information, see Add an ApsaraDB database instance and Add a third-party or self-managed database instance. In the DTS console, you can add a database to DTS on the Database Connections page or the new configuration page. For more information, see Manage data connections.
	Database Type	Select AnalyticDB for PostgreSQL.
	Connection Type	Select Alibaba Cloud Instance.
	Instance Region	Select the region where the destination AnalyticDB for PostgreSQL instance resides.
	Instance ID	Select the ID of the destination AnalyticDB for PostgreSQL instance.
	Database Name	Enter the name of the database in the destination AnalyticDB for PostgreSQL instance where the synchronized objects will be stored.
	Database Account	Enter the account for the destination AnalyticDB for PostgreSQL instance. For information about the required permissions, see Create an account and grant permissions.
	Database Password	Enter the password for the specified database account.

In the lower part of the page, click Test Connectivity and Proceed.

If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must ensure that the ECS instance can access the database. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the whitelist of the database to allow DTS to access the database. For more information, see DTS server IP whitelist.
Warning
If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the ECS security group rules, security risks may arise. Therefore, before you use DTS to synchronize data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, or connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

Configure the task objects.

On the Configure Objects page, specify the objects to synchronize.

Parameter	Description
Synchronization Types	The synchronization types. By default, Incremental Data Synchronization is selected. You must also select Schema Synchronization and Full Data Synchronization. After the precheck is complete, DTS synchronizes the historical data of the selected objects from the source database to the destination cluster. The historical data is the basis for subsequent incremental synchronization.
DDL and DML Operations to Be Synchronized	Select the DDL or DML operations to synchronize at the instance level. For information about the supported operations, see Supported SQL operations. Note To select SQL operations for a database or table, right-click a synchronization object in the Selected Objects box and select the SQL operations from the dialog box that appears.
Processing Mode of Conflicting Tables	Precheck and Report Errors: Checks for tables with the same names in the destination database. If any tables with the same names are found, an error is reported during the precheck and the data synchronization task does not start. Otherwise, the precheck is successful. Note If you cannot delete or rename the table with the same name in the destination database, you can map it to a different name in the destination. For more information, see Database Table Column Name Mapping. Ignore Errors and Proceed: Skips the check for tables with the same name in the destination database. Warning Selecting Ignore Errors and Proceed may cause data inconsistency and put your business at risk. For example: If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database: During full data synchronization, DTS retains the destination record and skips the source record. During incremental synchronization, DTS overwrites the destination record with the source record. If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.
Storage Engine Type	Select the storage engine type for the destination tables. The default value is Beam. Note This parameter is available only when the kernel version of the destination AnalyticDB for PostgreSQL instance is v7.0.6.6 or later, and Synchronization Types is selected for Schema Synchronization.
Capitalization of Object Names in Destination Instance	Configure the case-sensitivity policy for database, table, and column names in the destination instance. By default, the DTS default policy is selected. You can also choose to use the default policy of the source or destination database. For more information, see Case policy for destination object names.
Source Objects	In the Source Objects box, click the objects, and then click to move them to the Selected Objects box. Note Synchronization is at the table level. Other objects such as views, triggers, and stored procedures are not synchronized to the destination database.
Selected Objects	To rename a single object in the destination instance, right-click the object in the Selected Objects box. For more information, see Map a single object name. To rename multiple objects in bulk, click Batch Edit in the upper-right corner of the Selected Objects box. For more information, see Map multiple object names in bulk. Note To select SQL operations to synchronize at the schema or table level, right-click the object in the Selected Objects box and select the desired SQL operations in the dialog box that appears. For information about the supported operations, see Supported SQL operations. To filter data by using a WHERE clause, right-click the table in the Selected Objects box and specify a filter condition in the dialog box that appears. For instructions, see Configure a filter condition.

Click Next: Advanced Settings.

Parameter	Description
Dedicated Cluster for Task Scheduling	By default, DTS uses a shared cluster for tasks, so you do not need to make a selection. For greater task stability, you can purchase a dedicated cluster to run the DTS synchronization task. For more information, see What is a DTS dedicated cluster?.
Retry Time for Failed Connections	If the connection to the source or destination database fails after the synchronization task starts, DTS reports an error and immediately begins to retry the connection. The default retry duration is 720 minutes. You can customize the retry time to a value from 10 to 1,440 minutes. We recommend a duration of 30 minutes or more. If the connection is restored within this period, the task resumes automatically. Otherwise, the task fails. Note If multiple DTS instances (e.g., Instance A and B) share a source or destination, DTS uses the shortest configured retry duration (e.g., 30 minutes for A, 60 for B, so 30 minutes is used) for all instances. DTS charges for task runtime during connection retries. Set a custom duration based on your business needs, or release the DTS instance promptly after you release the source/destination instances.
Retry Time for Other Issues	If a non-connection issue (e.g., a DDL or DML execution error) occurs, DTS reports an error and immediately retries the operation. The default retry duration is 10 minutes. You can also customize the retry time to a value from 1 to 1,440 minutes. We recommend a duration of 10 minutes or more. If the related operations succeed within the set retry time, the synchronization task automatically resumes. Otherwise, the task fails. Important The value of Retry Time for Other Issues must be less than that of Retry Time for Failed Connections.
Enable Throttling for Full Data Synchronization	During full data synchronization, DTS consumes read and write resources from the source and destination databases, which can increase their load. To mitigate pressure on the destination database, you can limit the migration rate by setting Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s). Note This parameter is available only if Synchronization Types is set to Full Data Synchronization. You can also adjust the rate of full data synchronization when the synchronization instance is running.
Enable Throttling for Incremental Data Synchronization	You can also limit the incremental synchronization rate to reduce pressure on the destination database by setting RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s).
Environment Tag	You can select an environment tag to identify the instance. In this example, no selection is required.
Configure ETL	Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: Enables the ETL feature. Enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: Disables the ETL feature.
Monitoring and Alerting	Choose whether to set up alerts. If the synchronization fails or the latency exceeds the specified threshold, DTS sends a notification to the alert contacts. No: No alerts are configured. Yes: Configures alerts. You must also set the alert threshold and alert contact. For more information, see Configure monitoring and alerting during task configuration.

Click Data Verification to configure a data verification task.
To use the data verification feature, see Configure data verification.
Optional: After you complete the preceding steps, click Next: Configure Database and Table Fields to configure the Type, Primary Key Column, and Distribution Key for the tables to be migrated in the destination AnalyticDB for PostgreSQL instance.
Note
- This step is available only if you select Schema Synchronization when you configure the synchronization objects. You can set Definition Status to All to make modifications.
- The Primary Key Column can be a composite primary key that consists of multiple columns, and you must select one or more of the Primary Key Column as the Distribution Key.
- For detailed information about primary key columns and distribution keys, see Manage data tables and Define table distribution.

Save the task and perform a precheck.
- To view the parameters for configuring this instance via an API operation, hover over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the tooltip.
- If you have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.
Note
- Before a synchronization task starts, DTS performs a precheck. You can start the task only if the precheck passes.
- If the precheck fails, click View Details next to the failed item, fix the issue as prompted, and then rerun the precheck.
- If the precheck generates warnings:
  For non-ignorable warning, click View Details next to the item, fix the issue as prompted, and run the precheck again.
  For ignorable warnings, you can bypass them by clicking Confirm Alert Details, then Ignore, and then OK. Finally, click Precheck Again to skip the warning and run the precheck again. Ignoring precheck warnings may lead to data inconsistencies and other business risks. Proceed with caution.
When the Success Rate reaches 100%, click Next: Purchase Instance.

Purchase the instance.

On the Purchase page, select the billing method and link specifications for the data synchronization instance. For more information, see the following table.

Category	Parameter	Description
New Instance Class	Billing Method	Subscription: You pay upfront for a specific duration. This is cost-effective for long-term, continuous tasks. Pay-as-you-go: You are billed hourly for actual usage. This is ideal for short-term or test tasks, as you can release the instance at any time to save costs.
	Resource Group Settings	The resource group to which the instance belongs. The default is default resource group. For more information, see What is Resource Management?.
	Instance Class	DTS offers synchronization specifications at different performance levels that affect the synchronization rate. Select a specification based on your business requirements. For more information, see Data synchronization link specifications.
	Subscription Duration	In subscription mode, select the duration and quantity of the instance. Monthly options range from 1 to 9 months. Yearly options include 1, 2, 3, or 5 years. Note This option appears only when the billing method is Subscription.

Read and select the checkbox for Data Transmission Service (Pay-as-you-go) Service Terms.
Click Buy and Start, and then click OK in the OK dialog box.
You can monitor the task progress on the data synchronization page.