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Data Transmission Service:Migrate data between self-managed Oracle databases

Last Updated:Jul 07, 2023

This topic describes how to migrate data between self-managed Oracle databases by using Data Transmission Service (DTS). DTS supports schema migration, full data migration, and incremental data migration. You can select all of the supported migration types to ensure service continuity.

Prerequisites

  • The version of the self-managed Oracle database is 9i, 10g, 11g, 12c, 18c, or 19c.

  • The self-managed Oracle database is running in ARCHIVELOG mode. Archived log files are accessible, and a suitable retention period is set for archived log files. For more information, see Managing Archived Redo Log Files.
  • Supplemental logging, including SUPPLEMENTAL_LOG_DATA_PK and SUPPLEMENTAL_LOG_DATA_UI, is enabled for the self-managed Oracle database. For more information, see Supplemental Logging.

Usage notes

Note
  • During schema migration, DTS migrates foreign keys from the source database to the destination database.
  • During full data migration and incremental data migration, DTS temporarily disables the constraint check and cascade operations on foreign keys at the session level. If you perform the cascade and delete operations on the source database during data migration, data inconsistency may occur.
CategoryDescription
Limits on the source database
  • The server to which the source database belongs must have sufficient outbound bandwidth. Otherwise, the data migration speed decreases.
  • If the source database is an Oracle RAC database connected over Express Connect, you must specify a VIP for the database when you configure the source database information.
  • If the source database is an Oracle RAC database connected over Express Connect, VPN Gateway, Smart Access Gateway, Database Gateway, or Cloud Enterprise Network (CEN), you can use a single VIP rather than a Single Client Access Name (SCAN) IP address when you configure the source database information. After you specify the VIP, node failover is not supported for the Oracle RAC database.
  • Requirements for the objects to be migrated:
    • The tables to be migrated must have PRIMARY KEY or UNIQUE constraints, and all fields must be unique. Otherwise, the destination database may contain duplicate data records.
    • If the version of your Oracle database is 12c or later, the names of the tables to be migrated cannot exceed 30 bytes in length.
    • If you select tables as the objects to be migrated and you need to modify the tables in the destination database, such as renaming tables or columns, up to 1,000 tables can be migrated in a single data migration task. If you run a task to migrate more than 1,000 tables, a request error occurs. In this case, we recommend that you split the tables and configure multiple tasks to migrate the tables, or configure a task to migrate the entire database.
  • If you want to migrate incremental data, you must make sure that the following requirements are met:
    • The redo logging and archive logging must be enabled.
    • If you perform only incremental data migration, the redo logs and archive logs of the source database must be stored for more than 24 hours. If you perform both full data migration and incremental data migration, the redo logs and archive logs of the source database must be stored for at least seven days. After full data migration is complete, you can set the retention period to more than 24 hours. Otherwise, DTS may fail to obtain the redo logs and archive logs and the task may fail. In extreme cases, data may be inconsistent or lost. Make sure that you set the retention period of redo logs and archive logs based on the preceding requirements. Otherwise, the service reliability and performance stated in the Service Level Agreement (SLA) of DTS may not be guaranteed.

  • Limits on operations:
    • During schema migration and full data migration, do not perform DDL operations to change the schemas of databases or tables. Otherwise, the data migration task fails.
    • If you perform only full data migration, do not write data to the source database during data migration. Otherwise, data inconsistency may occur between the source and destination databases. To ensure data consistency, we recommend that you select schema migration, full data migration, and incremental data migration as the migration types.
    • During data migration, do not update LONGTEXT fields. Otherwise, the data migration task fails.
Other limits
  • Before you migrate data, evaluate the impact of data migration on the performance of the source and destination databases. We recommend that you migrate data during off-peak hours. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads on the database servers.
  • During full data migration, concurrent INSERT operations cause fragmentation in the tables of the destination database. After full data migration is complete, the size of used tablespace of the destination database is larger than that of the source database.
  • DTS attempts to resume data migration tasks that failed within the last seven days. Before you switch workloads to the destination database, stop or release the data migration task. You can also execute the REVOKE statement to revoke the write permissions from the accounts that are used by DTS to access the destination database. Otherwise, the data in the source database overwrites the data in the destination database after a failed task is resumed.
Migration typeInstance configuration feeInternet traffic fee
Schema migration and full data migrationFree of charge. Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Billing overview.
Incremental data migrationCharged. For more information, see Billing overview.

Migration types

Migration type

Description

Schema migration

DTS migrates the schemas of the selected objects to the destination Oracle database. DTS supports schema migration for the following types of objects: table, view, synonym, trigger, stored procedure, stored function, package, and user-defined type.

Note

In this scenario, DTS does not support schema migration for triggers. We recommend that you delete the triggers of the source database to prevent data inconsistency caused by triggers. For more information, see Configure a data synchronization task for a source database that contains a trigger.

Full data migration

DTS migrates the existing data of objects from the source Oracle database to the destination Oracle database.

Note

During schema migration and full data migration, we recommend that you do not perform DDL operations on the objects to be migrated. Otherwise, the objects may fail to be migrated.

Incremental data migration

After full data migration, DTS retrieves redo log files from the source Oracle database. Then, DTS migrates incremental data from the source Oracle database to the destination Oracle database. Incremental data migration ensures service continuity when you migrate data between Oracle databases.

SQL operations that can be incrementally migrated

Operation type

SQL statement

DML

INSERT, UPDATE, and DELETE

DDL

  • CREATE TABLE

    Note

    If a CREATE TABLE statement creates a table that contains partitions or functions, DTS does not migrate the statement.

  • ALTER TABLE, ADD COLUMN, DROP COLUMN, RENAME COLUMN, and ADD INDEX

  • DROP TABLE

  • RENAME TABLE, TRUNCATE TABLE, and CREATE INDEX

Before you begin

Log on to the self-managed Oracle database, create an account that you want to use to collect data, and then grant permissions to the account.

Note If you have created an account that is granted the permissions listed in the following table, you can skip this step.

Database type

Schema migration

Full data migration

Incremental data migration

Source self-managed Oracle database

Permissions of the schema owner

Permissions of the schema owner

Permissions of the database administrator (DBA)

Destination Oracle database

Permissions of the schema owner

To create a database account and grant permissions to the database account, perform the following operations:

Self-managed Oracle database: CREATE USER and GRANT.

Important

If you need to migrate incremental data from an Oracle database but the database administrator (DBA) permissions cannot be granted to the database account, you can enable archive logging and supplemental logging, and grant fine-grained permissions to the account.

  1. Enable archive logging and supplemental logging.

    Type

    Procedure

    Archive logging

    Execute the following statements to enable archive logging:

    shutdown immediate;
    startup mount;
    alter database archivelog;
    alter database open;
    archive log list;

    Supplemental logging

    Enable supplemental logging at the database or table level based on your business requirements.

    Note

    You can enable database-level supplemental logging to ensure the stability of Data Transmission Service (DTS) tasks. You can enable table-level supplemental logging to reduce the disk usage of the source Oracle database.

    • Enable database-level supplemental logging

      1. Execute the following statement to enable minimal supplemental logging:

        alter database add supplemental log data;
      2. Execute the following statement to enable primary key and unique key supplemental logging at the database level:

        alter database add supplemental log data (primary key,unique index) columns;
    • Enable table-level supplemental logging

      1. Execute the following statement to enable minimal supplemental logging:

        alter database add supplemental log data;
      2. Enable table-level supplemental logging by using one of the following methods:

        • Enable primary key supplemental logging at the table level

          alter table table_name add supplemental log data (primary key) columns;
        • Enable table-level supplemental logging for all columns

          alter table tb_name add supplemental log data (all) columns;

    Force logging

    Execute the following statement to enable force logging:

    alter database force logging;
  2. Grant fine-grained permissions to an Oracle database account.

    # Create a database account named rdsdt_dtsacct and grant permissions to the account.
    create user rdsdt_dtsacct IDENTIFIED BY rdsdt_dtsacct;
    grant create session to rdsdt_dtsacct;
    grant connect to rdsdt_dtsacct;
    grant resource to rdsdt_dtsacct;
    grant execute on sys.dbms_logmnr to rdsdt_dtsacct;
    grant select on V_$LOGMNR_LOGS to rdsdt_dtsacct;
    grant select on  all_objects to rdsdt_dtsacct;
    grant select on  all_tab_cols to rdsdt_dtsacct;
    grant select on  dba_registry to rdsdt_dtsacct;
    grant select any table to rdsdt_dtsacct;
    grant select any transaction to rdsdt_dtsacct;
    -- v$log privileges
    grant select on v_$log to rdsdt_dtsacct;
    -- v$logfile privileges
    grant select on v_$logfile to rdsdt_dtsacct;
    -- v$archived_log privileges
    grant select on v_$archived_log to rdsdt_dtsacct;
    -- v$parameter privileges
    grant select on v_$parameter to rdsdt_dtsacct;
    -- v$database privileges
    grant select on v_$database to rdsdt_dtsacct;
    -- v$active_instances privileges
    grant select on v_$active_instances to rdsdt_dtsacct;
    -- v$instance privileges
    grant select on v_$instance to rdsdt_dtsacct;
    -- v$logmnr_contents privileges
    grant select on v_$logmnr_contents to rdsdt_dtsacct;
    -- system tables
    grant select on sys.USER$ to rdsdt_dtsacct;
    grant select on SYS.OBJ$ to rdsdt_dtsacct;
    grant select on SYS.COL$ to rdsdt_dtsacct;
    grant select on SYS.IND$ to rdsdt_dtsacct;
    grant select on SYS.ICOL$ to rdsdt_dtsacct;
    grant select on SYS.CDEF$ to rdsdt_dtsacct;
    grant select on SYS.CCOL$ to rdsdt_dtsacct;
    grant select on SYS.TABPART$ to rdsdt_dtsacct;
    grant select on SYS.TABSUBPART$ to rdsdt_dtsacct;
    grant select on SYS.TABCOMPART$ to rdsdt_dtsacct;
    grant select_catalog_role TO rdsdt_dtsacct;
    
    # Switch to the pluggable database (PDB). Create a database account named rdsdt_dtsacct and grant permissions to the account.
    ALTER SESSION SET container = ORCLPDB1;
    create user rdsdt_dtsacct IDENTIFIED BY rdsdt_dtsacct;
    grant create  session to rdsdt_dtsacct;
    grant connect  to rdsdt_dtsacct;
    grant resource to rdsdt_dtsacct;
    grant execute on sys.dbms_logmnr to rdsdt_dtsacct;
    grant select on  all_objects to rdsdt_dtsacct;
    grant select on  all_tab_cols to rdsdt_dtsacct;
    grant select on  dba_registry to rdsdt_dtsacct;
    grant select any table to rdsdt_dtsacct;
    grant select any transaction to rdsdt_dtsacct;
    -- v$log privileges
    grant select on v_$log to rdsdt_dtsacct;
    -- v$logfile privileges
    grant select on v_$logfile to rdsdt_dtsacct;
    -- v$archived_log privileges
    grant select on v_$archived_log to rdsdt_dtsacct;
    -- v$parameter privileges
    grant select on v_$parameter to rdsdt_dtsacct;
    -- v$database privileges
    grant select on v_$database to rdsdt_dtsacct;
    -- v$active_instances privileges
    grant select on v_$active_instances to rdsdt_dtsacct;
    -- v$instance privileges
    grant select on v_$instance to rdsdt_dtsacct;
    -- v$logmnr_contents privileges
    grant select on v_$logmnr_contents to rdsdt_dtsacct;
    grant select on sys.USER$ to rdsdt_dtsacct;
    grant select on SYS.OBJ$ to rdsdt_dtsacct;
    grant select on SYS.COL$ to rdsdt_dtsacct;
    grant select on SYS.IND$ to rdsdt_dtsacct;
    grant select on SYS.ICOL$ to rdsdt_dtsacct;
    grant select on SYS.CDEF$ to rdsdt_dtsacct;
    grant select on SYS.CCOL$ to rdsdt_dtsacct;
    grant select on SYS.TABPART$ to rdsdt_dtsacct;
    grant select on SYS.TABSUBPART$ to rdsdt_dtsacct;
    grant select on SYS.TABCOMPART$ to rdsdt_dtsacct;
    -- V$PDBS privileges
    grant select on V_$PDBS to rdsdt_dtsacct;
    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;
    
    # Switch to the CDB$ROOT, which is the root container of the container database (CDB). Create a database account and grant permissions to the account.
    ALTER SESSION SET container = CDB$ROOT;
    # Create a database account named rdsdt_dtsacct and grant permissions to the account. You must modify the default parameters of the Oracle database. 
    alter session set "_ORACLE_SCRIPT"=true;
    create user rdsdt_dtsacct IDENTIFIED BY rdsdt_dtsacct;
    grant create session to rdsdt_dtsacct;
    grant connect to rdsdt_dtsacct;
    grant select on v_$logmnr_contents to rdsdt_dtsacct;
    grant LOGMINING TO rdsdt_dtsacct;
    grant EXECUTE_CATALOG_ROLE to rdsdt_dtsacct;
    grant execute on sys.dbms_logmnr to rdsdt_dtsacct;
    
    # Create a database account named rdsdt_dtsacct and grant permissions to the account.
    create user rdsdt_dtsacct IDENTIFIED BY rdsdt_dtsacct;
    grant create  session to rdsdt_dtsacct;
    grant connect  to rdsdt_dtsacct;
    grant resource to rdsdt_dtsacct;
    grant select on V_$LOGMNR_LOGS to rdsdt_dtsacct;
    grant select on  all_objects to rdsdt_dtsacct;
    grant select on  all_tab_cols to rdsdt_dtsacct;
    grant select on  dba_registry to rdsdt_dtsacct;
    grant select any table to rdsdt_dtsacct;
    grant select any transaction to rdsdt_dtsacct;
    grant select on v$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;
    -- v$log privileges
    grant select on v_$log to rdsdt_dtsacct;
    -- v$logfile privileges
    grant select on v_$logfile to rdsdt_dtsacct;
    -- v$archived_log privileges
    grant select on v_$archived_log to rdsdt_dtsacct;
    -- v$parameter privileges
    grant select on v_$parameter to rdsdt_dtsacct;
    -- v$database privileges
    grant select on v_$database to rdsdt_dtsacct;
    -- v$active_instances privileges
    grant select on v_$active_instances to rdsdt_dtsacct;
    -- v$instance privileges
    grant select on v_$instance to rdsdt_dtsacct;
    -- v$logmnr_contents privileges
    grant select on v_$logmnr_contents to rdsdt_dtsacct;
    grant select on sys.USER$ to rdsdt_dtsacct;
    grant select on SYS.OBJ$ to rdsdt_dtsacct;
    grant select on SYS.COL$ to rdsdt_dtsacct;
    grant select on SYS.IND$ to rdsdt_dtsacct;
    grant select on SYS.ICOL$ to rdsdt_dtsacct;
    grant select on SYS.CDEF$ to rdsdt_dtsacct;
    grant select on SYS.CCOL$ to rdsdt_dtsacct;
    grant select on SYS.TABPART$ to rdsdt_dtsacct;
    grant select on SYS.TABSUBPART$ to rdsdt_dtsacct;
    grant select on SYS.TABCOMPART$ to rdsdt_dtsacct;
    grant LOGMINING TO rdsdt_dtsacct;
    grant EXECUTE_CATALOG_ROLE to rdsdt_dtsacct;
    grant execute on sys.dbms_logmnr to rdsdt_dtsacct;
    grant select_catalog_role TO rdsdt_dtsacct;

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
  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. On the page that appears, configure the source and destination databases.

    Warning After you select the source and destination instances, we recommend that you read the limits displayed at the top of the page. This helps ensure that the task properly runs or prevent data inconsistency.

    Section

    Parameter

    Description

    N/A

    Task Name

    The name of the task. DTS automatically generates a task name. We recommend that you specify an informative name to identify the task. You do not need to specify a unique task name.

    Source Database

    Database Type

    The type of the source database. Select Oracle.

    Access Method

    The access method of the source database. In this example, Public IP Address is selected.

    Note

    If you select other access methods, you must set up the environment that is required for the self-managed Oracle database. For more information, see Preparation overview.

    Instance Region

    The region in which the source Oracle database resides.

    Hostname or IP address

    The endpoint that is used to connect to the self-managed Oracle database.

    Port Number

    The service port number of the self-managed Oracle database. Default value: 1521.

    Note

    In this example, the service port of the self-managed Oracle database must be accessible over the Internet.

    Oracle Type

    • 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 account of the source Oracle database. For more information about the permissions that are required for the account, see Before you begin.

    Database Password

    The password of the database account.

    Destination Database

    Database Type

    The type of the destination database. Select Oracle.

    Access Method

    The access method of the destination database. In this example, Public IP Address is selected.

    Note

    If you select other access methods, you must set up the environment that is required for the self-managed Oracle database. For more information, see Preparation overview.

    Instance Region

    The region in which the destination Oracle database resides.

    Hostname or IP Address

    The endpoint of the primary node in the destination Oracle database.

    Port Number

    The service port number of the destination database. Default value: 1521.

    Oracle Type

    • 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 account of the destination Oracle database. For more information about the permissions that are required for the account, see Before you begin.

    Database Password

    The password of the database account.

  4. If a whitelist is configured for your self-managed database, you must add the CIDR blocks of DTS servers to the whitelist. Then, click Test Connectivity and Proceed.
    Warning If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of a database or an 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: enhance the security of your username and password, limit the ports that are exposed, authenticate API calls, regularly check the whitelist or ECS security group rules and forbid unauthorized CIDR blocks, or connect the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.
  5. Configure objects to migrate and advanced settings.

    Parameter

    Description

    Migration Type

    • 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 Incremental Data Migration is not selected, we recommend that you do not write data to the source instance during data migration. This ensures data consistency between the source and destination instances.

    Processing Mode of Conflicting Tables

    • Precheck and Report Errors: checks whether the destination database contains tables that have the same names as tables in the source database. If the source and destination databases do not contain identical table names, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started.

      Note You can use the object name mapping feature to rename the tables that are migrated to the destination database. You can use this feature if the source and destination databases contain tables that have identical names and the tables in the destination database cannot be deleted or renamed. 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 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 some 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 Rightwards arrow icon to add the objects to the Selected Objects section.

    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 are dependent on the object may fail to be migrated.

    • To specify WHERE conditions to filter data, right-click an object in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information about the procedure, see Use SQL conditions to filter data.

    • To select the DDL or DML 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 DML or DDL operations that you want to migrate. For more information about the DML and DDL operations that can be migrated, see SQL operations that can be incrementally migrated.

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

    Parameter

    Description

    Set Alerts

    Specifies whether to set alerts for the data migration task. If the task fails or the migration latency exceeds the threshold, the alert contacts will receive notifications. Valid values:

    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 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 reconnects to the source and destination databases within the specified time range, DTS resumes the data migration task. Otherwise, the data migration task fails.
    Note
    • If you set different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is set later takes precedence.
    • If DTS retries a connection, you are charged for the operation of the DTS instance. We recommend that you specify the retry time based on your business needs and release the DTS instance at your earliest opportunity after the source and destination instances 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 the DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the 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 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.

    Configure ETL

    Specifies whether to configure the extract, transform, and load (ETL) feature. For more information, see What is ETL?. Valid values:
  7. In the lower part of the page, click Next: Save Task Settings and Precheck.
    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 troubleshoot the issues based on the causes, run a precheck again.
    • If an alert is triggered for an item during the precheck:
      • If an alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issues. Then, run a precheck again.
      • If an 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.
  8. Wait until the Success Rate value becomes 100%. Then, click Next: Purchase Instance.
  9. On the Purchase Instance page, specify the Instance Class parameter for the data migration instance. The following table describes the parameter.
    SectionParameterDescription
    ParametersInstance Class

    DTS provides several 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.

  10. Read and select the check box to agree to Data Transmission Service (Pay-as-you-go) Service Terms.
  11. Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.