Migrate data from a self-managed Oracle database to an AnalyticDB for MySQL V3.0 cluster - Data Transmission Service

This topic describes how to migrate data from a self-managed Oracle database to an AnalyticDB for MySQL V3.0 cluster by using Data Transmission Service (DTS). 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 the supported migration types to ensure service continuity.

Prerequisites

The destination AnalyticDB for MySQL V3.0 cluster is created. The available storage space of the destination AnalyticDB for MySQL V3.0 cluster is larger than the total size of the data in the source self-managed Oracle database. For more information, see Create a cluster.
Note
For more information about the supported database versions, see Overview of data migration scenarios.
The self-managed Oracle database is running in ARCHIVELOG mode. Archived log files are accessible and an appropriate retention period is set for archived log files. For more information, see Managing Archived Redo Log Files.
The supplemental logging feature is enabled for the self-managed Oracle database, and the SUPPLEMENTAL_LOG_DATA_PK and SUPPLEMENTAL_LOG_DATA_UI parameters are set to Yes. For more information, see Supplemental Logging.
You are familiar with the capabilities and limits of DTS if it is used to migrate data from an Oracle database. Advanced Database & Application Migration (ADAM) is used for database evaluation. This helps you smoothly migrate data to the cloud. For more information, see Prepare an Oracle database and Overview.

Limits

Note

During schema migration, DTS does not migrate 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 update and delete operations on the source database during data migration, data inconsistency may occur.

Category	Description
Limits on the source database	Bandwidth requirements: 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. 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. After you specify the VIP, node failover is not supported for the Oracle RAC database. If a field in the source Oracle database contains an empty string of the VARCHAR2 type, which is evaluated as null in the Oracle database, and the corresponding field in the destination database has a NOT NULL constraint, the migration task fails. 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 configure multiple tasks to migrate the tables in batches or configure a task to migrate the entire database. To perform incremental migration, you must make sure that the following requirements are met: The redo logging and archive logging must be enabled. The redo logs and archive logs of the source database must be stored for at least seven days. Otherwise, DTS may fail to obtain the redo logs and archive logs and the task may fail. In exceptional circumstances, data inconsistency or loss may occur. Make sure that you set the retention period of redo logs and archive logs based on the preceding requirements. Otherwise, the service level agreement (SLA) of DTS does not guarantee service reliability or performance. Limits on operations to be performed on the source database: 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 between the source and destination databases may occur. To ensure data consistency, we recommend that you select schema migration, full data migration, and incremental data migration as the migration types.
Other limits	Due to the limits of AnalyticDB for MySQL V3.0 clusters, if the disk space usage of the nodes in an AnalyticDB for MySQL V3.0 cluster exceeds 80%, an exception occurs in the DTS task and the DTS task is delayed. We recommend that you estimate the required disk space based on the objects to be migrated. You must make sure that the destination cluster has sufficient storage space. You must specify a custom primary key in the destination database or configure Primary Key Column during the Configurations for Databases, Tables, and Columns. Otherwise, data may fail to be migrated. If the destination AnalyticDB for MySQL V3.0 cluster is being backed up while the DTS task is running, the DTS task fails. External tables cannot be migrated. Before you migrate data, evaluate the impact of data migration on the performance of the source database and destination cluster. We recommend that you migrate data during off-peak hours. During full data migration, DTS uses the read and write resources of the source database and destination cluster. This may increase the loads on the database servers. During full data migration, concurrent INSERT operations cause fragmentation in the tables of the destination cluster. After full data migration is complete, the size of used tablespace of the destination cluster 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 cluster, you must stop or release the failed tasks. 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. If DDL statements fail to be executed in the destination database, the DTS task continues to run. You can view the DDL statements that fail to be executed in the task logs. For more information about how to view the task logs, see View task logs. During incremental data synchronization, do not use Oracle Data Pump to write data to the source database. Otherwise, data loss may occur. Make sure that the character sets of the source and destination databases are compatible. Otherwise, data inconsistency may occur or the migration task may fail. We recommend that you use the schema migration feature of DTS. Otherwise, the migration task may fail due to incompatible data types. The time zones of the source and destination databases must be the same. If a DTS task fails to run, DTS technical support will try to restore the task within 8 hours. During the restoration, the task may be restarted, and the parameters of the task may be modified. Note Only the parameters of the task may be modified. The parameters of databases are not modified. The parameters that may be modified include but are not limited to the parameters in the "Modify instance parameters" section of the Modify the parameters of a DTS instance topic.

Billing

Migration type	Instance configuration fee	Internet traffic fee
Schema migration and full data migration	Free of charge.	When the Access Method parameter of the destination database is set to Public IP Address, you are charged for Internet traffic. For more information, see Billing overview.
Incremental data migration	Charged. For more information, see Billing overview.

SQL operations that can be incrementally migrated

Operation type	SQL statement
DML	INSERT, UPDATE, and DELETE Note When data is written to the destination AnalyticDB for MySQL V3.0 cluster, the UPDATE statement is automatically converted to the REPLACE INTO statement. If the UPDATE statement is executed on the primary key, the UPDATE statement is converted to the DELETE and INSERT statements.

Data type mappings

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

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 permissions that are described in the following table, 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	Fine-grained permissions
AnalyticDB for MySQL V3.0 cluster	Read and write permissions on the destination database

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

Self-managed Oracle database: Prepare a database account, CREATE USER, and GRANT
For more information about how to create a database account for an AnalyticDB for MySQL V3.0 cluster, see Create a database account.

Important

If you want to migrate incremental data from an Oracle database, you must enable archive logging and supplemental logging for the Oracle database to obtain incremental data. For more information, see the Configure an Oracle database section of the Prepare an Oracle database topic.

Procedure

Use one of the following methods to go to the Data Migration page and select the region in which the data migration instance resides.
DTS console
1. Log on to the DTS console.
2. In the left-side navigation pane, click Data Migration.
3. In the upper-left corner of the page, select the region in which the data migration instance resides.
DMS console
Note
The actual operation 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.
1. Log on to the DMS console.
2. In the top navigation bar, move the pointer over Data + AI > DTS (DTS) > Data Migration.
3. From the drop-down list to the right of Data Migration Tasks, select the region in which the data synchronization instance resides.
Click Create Task to go to the task configuration page.

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 DTS task. DTS automatically generates a task name. We recommend that you specify an informative name that makes it easy to identify the task. You do not need to specify a unique task name.
Source Database	Select Existing Connection	If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections. Note In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list. If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.
	Database Type	The type of the source database. Select Oracle.
	Access Method	The access method of the source database. In this example, Self-managed Database on ECS is selected. Note If you select another access method, 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 self-managed Oracle database resides.
	ECS Instance ID	The ID of the Elastic Compute Service (ECS) instance that hosts the source self-managed Oracle database.
	Port Number	The service port number of the source self-managed Oracle database. Default value: 1521.
	Oracle Type	The architecture of the source self-managed Oracle 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, RAC or PDB Instance is selected.
	Database Account	The account of the source self-managed Oracle database. For information about the permissions that are required for the account, see the Before you begin section of this topic.
	Database Password	The password that is used to access the database instance.
Destination Database	Select Existing Connection	If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections. Note In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list. If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.
	Database Type	The type of the destination database. Select AnalyticDB for MySQL 3.0.
	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
	Instance Region	The region in which the destination AnalyticDB for MySQL V3.0 cluster resides.
	Instance ID	The ID of the destination AnalyticDB for MySQL V3.0 cluster.
	Database Account	The database account of the destination AnalyticDB for MySQL V3.0 cluster. For information about the permissions that are required for the account, see the Before you begin section of this topic.
	Database Password	The password that is used to access the database instance.

In the lower part of the page, click Test Connectivity and Proceed, and then click Test Connectivity in the CIDR Blocks of DTS Servers dialog box that appears.
Note
Make sure that the CIDR blocks of DTS servers can be automatically or manually added to the security settings of the source and destination databases to allow access from DTS servers. For more information, see Add the CIDR blocks of DTS servers.

Configure the objects to be migrated.

On the Configure Objects page, configure the objects that you want to migrate.

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 Schema Migration, make sure a database and a table are created in the destination database to receive data and the object name mapping feature is enabled in Selected Objects. 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.
DDL and DML Operations to Be Synchronized	The DDL or DML operations that you want to migrate. Note To select the SQL operations performed on a specific table, right-click an object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to migrate.
Merge Tables	Yes: If you select this value, DTS adds the `__dts_data_source` column to each table to record data sources. For more information, see Enable the multi-table merging feature. No: This is the default value. Note If you set this parameter to Yes, all of the selected source tables in the task are merged into a destination table. If you do not need to merge specific source tables, you can create a separate data migration task for these tables. Warning We recommend that you do not perform DDL operations to change the schemas of source databases or tables. Otherwise, data inconsistency may occur or the data migration task may fail.
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 Database, table, and column name mapping. 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, and a data record has the same primary key as an existing data record in the destination database, the following scenarios may occur: During full data migration, DTS does not migrate the data record to the destination database. The existing data record in the destination database is retained. During incremental data migration, DTS migrates the data record to the destination database. The existing data record in the destination database is overwritten. If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails. Proceed with caution.
Capitalization of Object Names in Destination Instance	The capitalization of database names, table names, and column names in the destination instance. By default, DTS default policy is selected. You can select other options to make sure that the capitalization of object names is consistent with that of the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.
Source Objects	Select one or more objects from the Source Objects section. 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 a single object in the destination instance, right-click the object in the Selected Objects section. For more information, see Rename objects to be migrated. To rename multiple objects in the destination instance, click Edit in the upper-right corner of the Selected Objects section. For more information, see Rename multiple objects to be migrated 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 Specify 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.

Click Next: Advanced Settings to configure advanced settings.

Parameter	Description
Dedicated Cluster for Task Scheduling	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 1,440. 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.
Retry Time for Other Issues	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 Retry Time for Other Issues 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 the Configure monitoring and alerting when you create a DTS task section of the Configure monitoring and alerting topic.

Click Next Step: Data Verification to configure the data verification task.
For more information about how to use the data verification feature, see Configure a data verification task.
Optional. After you complete the preceding configuration, click Next: Configure Database and Table Fields and configure the Type, Primary Key Column, Distribution Key, and partition key parameters such as Partition Key, Partitioning Rules, and Partition Lifecycle for the corresponding tables in the destination AnalyticDB for MySQL V3.0 cluster.
Note
- This step is available only if you select Schema Migration when you configure the objects to be migrated. You can set the Definition Status parameter to All and modify the fields.
- In the Primary Key Column field, you can specify multiple columns to form a composite primary key. In this case, you must specify one or more primary key columns as the Distribution Key and Partition Key. For more information, see CREATE TABLE.

Save the task settings and run a precheck.
- To view the parameters to be specified when you call the relevant API operation to configure the DTS task, move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters.
- If you do not need to view or have viewed the parameters, click Next: Save Task Settings and Precheck in the lower part of the page.
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 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 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.

Purchase an instance.

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

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	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 instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Instance classes of data migration instances.

Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.
Click Buy and Start. In the message that appears, click OK.
You can view the progress of the task on the Data Migration page.
Note
- If a data migration task cannot be used to migrate incremental data, the task automatically stops. The Completed is displayed in the Status section.
- If a data migration task can be used to migrate incremental data, the task does not automatically stop. The incremental data migration task never stops or completes. The Running is displayed in the Status section.