Data Transmission Service:Migrate data from an Amazon RDS for Oracle instance to a PolarDB for PostgreSQL (Compatible with Oracle) cluster

Limits

Billing

Migration types

Data type mappings

For more information, see Data type mappings between heterogeneous databases.

SQL operations that can be incrementally migrated

Permissions required for database accounts

For more information about how to create an account and grant permissions to the account, see the following topics:

• Amazon RDS for Oracle instance: Prepare a database account, CREATE USER, and GRANT

• PolarDB for PostgreSQL (Compatible with Oracle) cluster: Create a database account

Before you begin

1. Log on to the Amazon RDS Management Console.

2. Go to the basic information page of the Amazon RDS for Oracle instance.

3. In the Security group rules section, click the name of the security group to which the existing inbound rule belongs.

   

4. Add the CIDR blocks of DTS servers that reside in the corresponding region (port number: 1521) to the inbound rule. For more information, see Add the CIDR blocks of DTS servers.

   Note

   • You need to add only the CIDR blocks of DTS servers that reside in the same region as the destination database. For example, the source database resides in the Singapore region and the destination database resides in the China (Hangzhou) region. You need to add only the CIDR blocks of DTS servers that reside in the China (Hangzhou) region.

   • You can add all of the required CIDR blocks to the inbound rule at a time.

   • If you have other questions, see the official documentation of Amazon or contact technical support.

5. Modify the log settings of the Amazon RDS for Oracle instance. Skip this step if you do not need to perform incremental data migration.

   • If the database version of the Amazon RDS for Oracle instance is 12c or later (non-multitenant architecture), perform the following steps to configure the log settings:

     1. Use the master user account and the SQL*Plus tool to connect to the Amazon RDS for Oracle instance.

     2. Enable archive logging and supplemental logging.

        Type	Procedure
        Archive logging	Execute the following statement to check whether archive logging is enabled: SELECT LOG_MODE FROM v$database; View and set the retention period for archived logs. Note We recommend that you set the retention period of archived logs to at least 72 hours. In this example, the retention period is set to 72 hours. exec rdsadmin.rdsadmin_util.show_configuration; exec rdsadmin.rdsadmin_util.set_configuration('archivelog retention hours', 72);
        Supplemental logging	Enable supplemental logging at the database or table level: Enable database-level supplemental logging Execute the following statement to check whether database-level supplemental logging is enabled: SELECT supplemental_log_data_min, supplemental_log_data_pk, supplemental_log_data_ui FROM v$database; Enable primary key and unique key supplemental logging at the database level: exec rdsadmin.rdsadmin_util.alter_supplemental_logging('ADD', 'PRIMARY KEY'); exec rdsadmin.rdsadmin_util.alter_supplemental_logging('ADD', 'UNIQUE'); Enable table-level supplemental logging by using one of the following methods: Enable table-level supplemental logging for all columns: exec rdsadmin.rdsadmin_util.alter_supplemental_logging('ADD', 'ALL'); Enable primary key supplemental logging at the table level: exec rdsadmin.rdsadmin_util.alter_supplemental_logging('ADD', 'PRIMARY KEY');

     3. Grant fine-grained permissions to the database account of the Amazon RDS for Oracle instance.

        Grant fine-grained permissions

        Webpack

        # Create a database account and grant permissions to the account. In this example, a database account named RDSDT_DTSACCT is created.
        create user RDSDT_DTSACCT IDENTIFIED BY RDSDT_DTSACCT;
        grant create session to RDSDT_DTSACCT;
        grant connect to RDSDT_DTSACCT;
        grant resource to RDSDT_DTSACCT;
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$LOGMNR_LOGS','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('ALL_OBJECTS','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('ALL_TAB_COLS','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('DBA_REGISTRY','RDSDT_DTSACCT','SELECT');
        grant select any table to RDSDT_DTSACCT;
        grant select any transaction to RDSDT_DTSACCT;
        -- v$log privileges
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$LOG','RDSDT_DTSACCT','SELECT');
        -- v$logfile privileges
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$LOGFILE','RDSDT_DTSACCT','SELECT');
        -- v$archived_log privileges
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$ARCHIVED_LOG','RDSDT_DTSACCT','SELECT');
        -- v$parameter privileges
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$PARAMETER','RDSDT_DTSACCT','SELECT');
        -- v$database privileges
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$DATABASE','RDSDT_DTSACCT','SELECT');
        -- v$active_instances privileges
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$ACTIVE_INSTANCES','RDSDT_DTSACCT','SELECT');
        -- v$instance privileges
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$INSTANCE','RDSDT_DTSACCT','SELECT');
        -- v$logmnr_contents privileges
        exec rdsadmin.rdsadmin_util.grant_sys_object('V_$LOGMNR_CONTENTS','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('USER$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('OBJ$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('COL$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('IND$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('ICOL$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('CDEF$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('CCOL$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('TABPART$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('TABSUBPART$','RDSDT_DTSACCT','SELECT');
        exec rdsadmin.rdsadmin_util.grant_sys_object('TABCOMPART$','RDSDT_DTSACCT','SELECT');
        grant LOGMINING TO RDSDT_DTSACCT;
        grant EXECUTE_CATALOG_ROLE to RDSDT_DTSACCT;
        exec rdsadmin.rdsadmin_util.grant_sys_object('DBMS_LOGMNR','RDSDT_DTSACCT','EXECUTE');
        grant select on v$database to rdsdt_dtsacct;
        grant select on dba_objects to rdsdt_dtsacct;
        grant select on DBA_TAB_COMMENTS to rdsdt_dtsacct;
        grant select on dba_tab_cols to rdsdt_dtsacct;
        grant select_catalog_role TO rdsdt_dtsacct;

   • If the database version of the Amazon RDS for Oracle instance is 9i, 10g, or 11g, perform the following steps to configure the log settings:

     1. Use the master user account and the SQL*Plus tool to connect to the Amazon RDS for Oracle instance.

     2. Run the archive log list; command to check whether the Amazon RDS for Oracle instance is running in ARCHIVELOG mode.

        Note

        If the instance is running in NOARCHIVELOG mode, switch the mode to ARCHIVELOG. For more information, see Managing Archived Redo Logs.

     3. Enable force logging.

        exec rdsadmin.rdsadmin_util.force_logging(p_enable => true);

     4. Enable supplemental logging for primary keys.

        begin rdsadmin.rdsadmin_util.alter_supplemental_logging(p_action => 'ADD',p_type => 'PRIMARY KEY');end;/

     5. Enable supplemental logging for unique keys.

        begin rdsadmin.rdsadmin_util.alter_supplemental_logging(p_action => 'ADD',p_type => 'UNIQUE');end;/

     6. Set a retention period for archived logs.

        begin rdsadmin.rdsadmin_util.set_configuration(name => 'archivelog retention hours', value => '24');end;/

     7. Set a retention period for archived logs.

        Note

        We recommend that you set the retention period of archived logs to at least 24 hours.

     8. Commit the changes.

        commit;

Procedure

1. Go to the Data Migration Tasks page.

   1. Log on to the Data Management (DMS) console.

   2. In the top navigation bar, click DTS.

   3. In the left-side navigation pane, choose DTS (DTS) > Data Migration.

   Note

   • Operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode and Customize the layout and style of the DMS console.

   • You can also go to the Data Migration Tasks page of the new DTS console.

2. From the drop-down list next to Data Migration Tasks, select the region in which the data migration instance resides.

   Note

   If you use the new DTS console, you must select the region in which the data migration instance resides in the upper-left corner.

3. Click Create Task. In the Create Data Migration Task wizard, configure the source and destination databases. The following table describes the parameters.

   Warning

   After you configure the source and destination databases, we recommend that you read the Limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.

   Section	Parameter	Description
   N/A	Task Name	The name of the task. DTS automatically assigns a name to the task. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
   Source Database	Select an existing DMS database instance. (Optional. If you have not registered a DMS database instance, ignore this option and configure database settings in the section below.)	The database instance that you want to use. You can choose whether to use an existing instance based on your business requirements. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must configure parameters for the source database.
   	Database Type	The type of the source database. Select Oracle.
   	Access Method	The access method of the source database. Select Public IP Address.
   	Instance Region	The region in which the source Amazon RDS for Oracle instance resides. Note If the region in which the source Amazon RDS for Oracle instance resides is not displayed in the drop-down list, select a region that is geographically closest to the source Amazon RDS for Oracle instance.
   	Domain Name or IP	The endpoint that is used to access the source Amazon RDS for Oracle instance.
   	Port Number	The service port number of the source Amazon RDS for Oracle instance. Default value: 1521.
   	Oracle Type	The architecture of the source database. If you select Non-RAC Instance, you must configure the SID parameter. If you select RAC or PDB Instance, you must configure the Service Name parameter. In this example, Non-RAC Instance is selected.
   	Database Account	The database account of the source Amazon RDS for Oracle instance. For information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
   	Database Password	The password of the database account.
   Destination Database	Select an existing DMS database instance. (Optional. If you have not registered a DMS database instance, ignore this option and configure database settings in the section below.)	The database instance that you want to use. You can choose whether to use an existing instance based on your business requirements. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must configure parameters for the source database.
   	Database Type	The type of the destination database. Select PolarDB (Compatible with Oracle).
   	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
   	Instance Region	The region where the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster resides.
   	Instance ID	The ID of the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster.
   	Database Name	The name of the database in the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster to which you want to migrate data.
   	Database Account	The database account of the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster. For information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
   	Database Password	The password of the database account.

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

5. If an IP address whitelist is configured for your self-managed database, add the CIDR blocks of DTS servers to the IP address whitelist. Then, click Test Connectivity and Proceed.

   Warning

   If the public CIDR blocks of DTS servers are automatically or manually added to the whitelist of a database instance or to the security group rules of an ECS instance, security risks may arise. Therefore, before you use DTS to migrate 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 security group rules and forbidding unauthorized CIDR blocks, or connecting the database instance to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

6. Configure the objects to be migrated and advanced settings. The following table describes the parameters.

   Parameter	Description
   Migration Types	To perform only full data migration, select Schema Migration and Full Data Migration. To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note If you do not select Incremental Data Migration, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases.
   Add a hidden primary key for a table without a primary key/a table without a unique key	If the objects to be migrated contain a table without a primary key or a unique key, you must set this parameter to Yes. DTS uses the ROWID column in the Oracle database as the hidden primary key (non-null unique key) of the destination table. This prevents duplicate data in the destination database. Note You can configure this parameter only if you select Schema Migration, Full Data Migration, and Incremental Data Migration for the Migration Types parameter.
   Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether the destination database contains tables that use the same names as tables in the source database. If the source and destination databases do not contain tables that have identical table names, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started. Note If the source and destination databases contain tables with identical names and the tables in the destination database cannot be deleted or renamed, you can use the object name mapping feature to rename the tables that are migrated to the destination database. For more information, see Map object names. Ignore Errors and Proceed: skips the precheck for identical table names in the source and destination databases. Warning If you select Ignore Errors and Proceed, data inconsistency may occur and your business may be exposed to the following potential risks: If the source and destination databases have the same schema, DTS does not migrate data records that have the same primary keys as data records in the destination database. If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails. Proceed with caution.
   Source Objects	Select one or more objects from the Source Objects section and click the icon to add the objects to the Selected Objects section. Note You can select columns, tables, or databases as the objects to be migrated.
   Selected Objects	To rename an object that you want to migrate to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object. To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time. Note If you use the object name mapping feature to rename an object, other objects that depend on the object may fail to be migrated. To specify WHERE conditions to filter data, right-click a table in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information, see Set filter conditions. To incrementally migrate the SQL operations performed on a specific database or table, right-click an object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to incrementally migrate. For more information about the SQL statements that can be incrementally migrated, see the SQL operations that can be incrementally migrated section of this topic.

7. Click Next: Advanced Settings to configure advanced settings.

   • Data Verification Settings

     For more information about how to use the data verification feature, see Configure data verification.

   • Advanced Settings

     Parameter	Description
     Select the dedicated cluster used to schedule the task	By default, DTS schedules the task to a shared cluster. You do not need to configure this parameter. You can purchase a dedicated cluster of the specified specifications to run data migration tasks. For more information, see What is a DTS dedicated cluster?
     Retry Time for Failed Connections	The retry time range for failed connections. If the source or destination database fails to be connected after the data migration task is started, DTS immediately retries a connection within the retry time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS is reconnected to the source and destination databases within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Note If you specify different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is specified later takes precedence. When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time range based on your business requirements. You can also release the DTS instance at the earliest opportunity after the source database and destination instance are released.
     The wait time before a retry when other issues occur in the source and destination databases.	The retry time range for other issues. For example, if DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the retry time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set the parameter to a value greater than 10. If the failed operations are successfully performed within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Important The value of the The wait time before a retry when other issues occur in the source and destination databases. parameter must be smaller than the value of the Retry Time for Failed Connections parameter.
     Enable Throttling for Full Data Migration	Specifies whether to enable throttling for full data migration. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads of the database servers. You can enable throttling for full data migration based on your business requirements. To configure throttling, you must configure the Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) parameters. This reduces the loads of the destination database server. Note You can configure this parameter only if you select Full Data Migration for the Migration Types parameter.
     Enable Throttling for Incremental Data Migration	Specifies whether to enable throttling for incremental data migration. To configure throttling, you must configure the RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) parameters. This reduces the loads of the destination database server. Note You can configure this parameter only if you select Incremental Data Migration for the Migration Types parameter.
     Environment Tag	The environment tag that is used to identify the DTS instance. You can select an environment tag based on your business requirements. In this example, no environment tag is selected.
     Actual Write Code	The encoding format in which data is written to the destination database. You can select an encoding format based on your business requirements.
     Configure ETL	Specifies whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: configures the ETL feature. You can enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: does not configure the ETL feature.
     Monitoring and Alerting	Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts receive notifications. Valid values: No: does not configure alerting. Yes: configures alerting. In this case, you must also configure the alert threshold and alert notification settings. For more information, see Configure monitoring and alerting when you create a DTS task.

8. In the lower part of the page, click Next: Save Task Settings and Precheck.

   You can move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters to view the parameters to be specified when you call the relevant API operation to configure the DTS task.

   Note

   • Before you can start the data migration task, DTS performs a precheck. You can start the data migration task only after the task passes the precheck.

   • If the task fails to pass the precheck, click View Details next to each failed item. After you analyze the causes based on the check results, troubleshoot the issues. Then, run a precheck again.

   • If an alert is generated for an item during the precheck, perform the following operations based on the scenario:

     • If the alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issues. Then, run a precheck again.

     • If the alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur and your business may be exposed to potential risks.

9. Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.

10. On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.

    Section	Parameter	Description
    New Instance Class	Resource Group Settings	The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?
    	Instance Class	DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Specifications of data migration instances.

11. Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.

12. Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.

What to do next

If the objects to be migrated contain a table without a primary key or a unique key and you set the Add a hidden primary key for a table without a primary key/a table without a unique key parameter to Yes, you must manually delete the hidden primary key that is added by DTS after you switch your business to the destination database and before you terminate or release the DTS instance. To do this, perform the following operation: On the Basic Information tab of the Full Data Migration or Incremental Write module, click Delete Invisible Primary Key in the Actions column.