Migrate data from a self-managed Oracle database to an ApsaraDB RDS for PostgreSQL instance - Data Transmission Service

This topic describes how to use Data Transmission Service (DTS) to migrate data from a self-managed Oracle database to an ApsaraDB RDS for PostgreSQL instance. DTS supports schema migration, full data migration, and incremental data migration. When you migrate data from a self-managed Oracle database, you can select all of the supported migration types to ensure service continuity.

Prerequisites

The version number 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.
The tables to migrate contain primary keys or UNIQUE NOT NULL indexes.
An ApsaraDB RDS for PostgreSQL instance is created. For more information, see Create an ApsaraDB RDS for PostgreSQL instance.

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.

Category	Description
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 Real Application Cluster (RAC) database connected over Express Connect, you must specify a virtual IP address (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.

Billing

Migration type	Task configuration fee	Internet traffic fee
Schema migration and full data migration	Free of charge.	Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Billing overview.
Incremental data migration	Charged. For more information, see Billing overview.

Migration types

Migration type	Description
Schema migration	DTS migrates the schemas of the required objects from the source database to the destination ApsaraDB RDS for PostgreSQL instance. 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 triggers. We recommend that you delete the triggers of the source database to prevent data inconsistency caused by triggers. For more information about, 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 self-managed Oracle database to the destination ApsaraDB RDS for PostgreSQL instance. Note During schema migration and full data migration, 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 is complete, DTS retrieves redo log files from the self-managed Oracle database. Then, DTS migrates incremental data from the self-managed Oracle database to the destination ApsaraDB RDS for PostgreSQL database. Incremental data migration ensures service continuity when you migrate data from the self-managed Oracle database to the destination ApsaraDB RDS for PostgreSQL instance.

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, subpartitions, or functions, DTS does not migrate the statement. In addition, DTS does not migrate the CREATE TABLE AS SELECT statement. ALTER TABLE, including ADD COLUMN, ADD INDEX, DROP COLUMN, DROP INDEX, MODIFY COLUMN, and RENAME COLUMN 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 a database account and the account has the following permissions, you can skip this step.

Database	Schema migration	Full data migration	Incremental data migration
Self-managed Oracle database	Permissions of the schema owner	Permissions of the schema owner	Permissions of the database administrator (DBA)
ApsaraDB RDS for PostgreSQL database	Permissions of the schema owner

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

Self-managed Oracle databases: CREATE USER and GRANT.
ApsaraDB RDS for PostgreSQL instances: Create an account on an ApsaraDB RDS for PostgreSQL instance

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.

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 Execute the following statement to enable minimal supplemental logging: `alter database add supplemental log data;` 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 Execute the following statement to enable minimal supplemental logging: `alter database add supplemental log data;` 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;`

Grant fine-grained permissions to an Oracle database account.

Oracle versions 9i to 11g Oracle versions 12c to 19c that use the multitenant architecture Oracle versions 12c to 19c that use a non-multitenant architecture

# 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

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 Configure the DMS console based on your business requirements.
- You can also go to the Data Migration Tasks page of the new DTS console.
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.

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

Warning After you configure the source and destination databases, we recommend that you read the limits displayed at the top of the page. Otherwise, the task may fail or data inconsistency may occur.

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 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 IP address that is used to access 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	The architecture of the source Oracle database. If you select Non-RAC Instance, you must specify the SID parameter. If you select RAC or PDB Instance, you must specify 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 PostgreSQL.
	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
	Instance Region	The region in which the destination ApsaraDB RDS for PostgreSQL instance resides.
	Instance ID	The ID of the destination ApsaraDB RDS for PostgreSQL instance.
	Database Account	The name of the destination database to which the objects are migrated.
	Database Account	The database account of the destination ApsaraDB RDS for PostgreSQL instance. For information about the permissions that are required for the account, see Before you begin.
	Database Password	The password of the database account.

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

Configure the objects to be migrated and advanced settings.

Basic Settings

Parameter or setting	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 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.
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 tables that have the same 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 specific columns are migrated or the data migration task fails. Proceed with caution.
Select Objects	Select one or more objects from the Source Objects section and click the icon to add the objects to the Selected Objects section.
Rename Databases and Tables	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 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.
Filter data	You can specify WHERE conditions to filter data. For more information, see Use SQL conditions to filter data.
Select the SQL operations to be incrementally migrated	In the Selected Objects section, right-click an object to be migrated. In the dialog box that appears, select the SQL operations that you want to migrate. For more information, see SQL operations that can be incrementally migrated.

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: No: does not set alerts. Yes: sets alerts. If you select Yes, you must also set the alert threshold and alert contacts. For more information,see Configure monitoring and alerting when you create a DTS task.
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 reconnects 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 set different retry time ranges for multiple data migration tasks that share the same source or destination instance, the value that is set 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 your earliest opportunity after the source database and destination instances are released.

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 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.
Wait until the Success Rate value becomes 100%. Then, click Next: Purchase Instance.

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

Section	Parameter	Description
New Instance Class	Resource Group	The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?.
New Instance Class	Instance Class	DTS provides various 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.

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