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Migrate from RDS MySQL to a self-managed Oracle database

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You can use Data Transmission Service (DTS) to migrate data from an ApsaraDB RDS for MySQL instance to a self-managed Oracle database.

Prerequisites

  • A self-managed Oracle database is created as the migration destination.

    Note

    The destination Oracle database must have more available storage space than the data to be migrated from the source ApsaraDB RDS for MySQL instance.

  • For self-managed Oracle databases that use a RAC architecture, a VPC connection to Alibaba Cloud is required. To ensure the DTS task runs correctly, connect the SCAN IP of the Oracle RAC and the VIP of each node to the VPC, and configure the necessary routing rules. For more information, see Overview of solutions for connecting an on-premises data center to Alibaba Cloud and Connect a data center to DTS through VPN Gateway.

Usage notes

Note

During full and incremental data migration:

  • If cascading update or delete operations exist in the source database, data inconsistencies may occur.

  • If foreign keys or triggers exist in the destination database, you must disable them. Otherwise, the data migration task may fail.

Type

Description

Source database limits

  • Tables to be migrated must have a primary key or a unique constraint, and the values in the constrained columns must be unique. Otherwise, duplicate data may occur in the destination database.

  • If you migrate data at the table level and need to perform editing (such as mapping table or column names), a single data migration task supports up to 1,000 tables. If this limit is exceeded, the task submission fails with an error. In this case, split the tables into multiple batches for migration or configure a task to migrate the entire database.

  • If you need incremental migration, enable binary logging:

    • Set binlog_format to ROW and binlog_row_image to FULL. Otherwise, the precheck fails and the task cannot start.

      Important

      If your self-managed MySQL source is a dual-master cluster—where each instance acts as both master and slave—enable the log_slave_updates parameter. This ensures DTS can read all binary logs.

    • For RDS for MySQL instances, retain local binary logs for at least three days (seven days recommended). For self-managed MySQL databases, retain local binary logs for at least seven days. If DTS cannot access binary logs, the task fails. In extreme cases, data inconsistency or data loss may occur. Issues caused by binary log retention periods shorter than DTS requires are not covered under the DTS SLA.

      Note

      To set the retention period for local binary logs on an RDS for MySQL instance, see Automatically delete local logs.

  • During the schema migration and full migration phases, do not perform DDL operations that change the database or table schema. Otherwise, the data migration task will fail.

    Note

    During the full migration phase, DTS queries the source database. This creates a metadata lock, which may block DDL operations on the source database.

  • If you perform only a full data migration, do not write new data to the source database. Otherwise, data inconsistency will occur between the source and destination databases. To maintain real-time data consistency, select schema migration, full data migration, and incremental data migration.

  • If you need incremental migration, RDS for MySQL instances that do not record transaction logs—such as RDS for MySQL 5.6 read-only instances—are not supported as sources.

  • DTS does not migrate data generated by changes that do not write to binary logs. Examples include data restored from physical backups or created by cascade operations.

    Note

    If this occurs, re-run full migration after your business allows it.

  • If your source MySQL database is version 8.0.23 or later and contains invisible hidden columns, DTS cannot read those columns. This may cause data loss.

    Note

    Run ALTER TABLE <table_name> ALTER COLUMN <column_name> SET VISIBLE; to make the hidden column visible. For more information, see Invisible Columns.

Other limits

  • Do not use tools such as pt-online-schema-change to perform online DDL operations on migration objects in the source database. Otherwise, the data migration task will fail.

  • If your source database uses temporary-table-mode online DDL operations—including multi-table merge scenarios—or adds function-based indexes to unique key columns, data loss or task failure may occur on the destination database.

  • For columns of the FLOAT or DOUBLE data type, DTS uses ROUND(COLUMN,PRECISION) to read the values. If a precision is not explicitly defined, DTS defaults to a migration precision of 38 for FLOAT and 308 for DOUBLE. Ensure the migration precision meets your business requirements.

  • Before you start a data migration, evaluate the performance of the source and destination databases. We recommend that you migrate data during off-peak hours because full data migration consumes read and write resources on both databases, which may increase the load.

  • During full data migration, concurrent INSERT operations cause table fragmentation in the destination database. Therefore, after the full data migration is complete, tables in the destination database occupy more tablespace than they do in the source instance.

  • DTS attempts to resume failed tasks within seven days. Before you switch your workloads to the destination instance, stop or release the instance, or use the REVOKE command to revoke write permissions from the account that DTS uses to access the destination instance. This prevents the task from automatically resuming and overwriting destination data.

  • If your RDS for MySQL instance has Always-Encrypted enabled, full migration is not supported.

    Note

    RDS for MySQL instances with Transparent Data Encryption (TDE) enabled support schema migration, full migration, and incremental migration.

  • If a task fails, DTS support staff will attempt to restore it within eight hours. During restoration, they may restart the task or adjust its parameters.

    Note

    Only DTS task parameters are modified—not database parameters. Parameters that may be adjusted include those listed in Modify instance parameters.

Special cases

  • For self-managed MySQL sources:

    • A master–standby switchover on the source database causes the migration task to fail.

    • DTS calculates latency by comparing the timestamp of the last record migrated to the destination database with the current time. If no DML operations run on the source for a long time, latency reporting becomes inaccurate. If latency appears too high, run a DML operation on the source to update the latency value.

      Note

      If you select full-database migration, create a heartbeat table. Update or write to it every second.

    • DTS periodically runs CREATE DATABASE IF NOT EXISTS `test` on the source database to advance the binary log offset.

    • If your source is Amazon Aurora MySQL or another clustered MySQL instance, ensure the domain name or IP address configured for the task—and its DNS resolution—always points to a read–write (RW) node. Otherwise, the migration task may fail.

  • For RDS for MySQL sources:

    • If you need incremental migration, RDS for MySQL instances that do not record transaction logs—such as RDS for MySQL 5.6 read-only instances—are not supported as sources.

    • DTS periodically runs CREATE DATABASE IF NOT EXISTS `test` on the source database to advance the binary log offset.

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.

Migration types

  • Schema migration

    DTS migrates the schemas of the migration objects from the source database to the destination database.

  • Full data migration

    DTS migrates all existing data in the migration objects from the source database to the destination database.

  • Incremental data migration

    After full data migration, DTS migrates incremental updates from the source database to the destination database, minimizing downtime for self-managed applications.

SQL operations for incremental migration

Operation type

SQL statement

DML

INSERT, UPDATE, and DELETE

DDL

CREATE TABLE, ALTER TABLE, RENAME TABLE, TRUNCATE TABLE, and DROP TABLE

Required permissions for database accounts

Database

Schema migration

Full migration

Incremental migration

ApsaraDB RDS for MySQL

SELECT permission

SELECT permission

REPLICATION SLAVE, REPLICATION CLIENT, and SELECT permissions for the source objects. DTS automatically grants these permissions to the database account.

Oracle

Schema owner permissions.

For more information about creating and authorizing a database account, see the following topics:

Procedure

This example uses a self-managed Oracle database on an ECS instance as the destination database.

  1. Navigate to the migration task list page for the destination region using one of the following methods.

    From the DTS console

    1. Log on to the Data Transmission Service (DTS) console.

    2. In the navigation pane on the left, click Data Migration.

    3. In the upper-left corner of the page, select the region where the migration instance is located.

    From the DMS console

    Note

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

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

    2. In the top menu bar, choose Data + AI > Data Transmission (DTS) > Data Migration.

    3. To the right of Data Migration Tasks, select the region where the migration instance is located.

  2. Click Create Task to navigate to the task configuration page.

  3. Configure the source and destination databases.

    Category

    Parameter

    Description

    N/A

    Task Name

    DTS automatically generates a task name. We recommend that you specify a descriptive name for easy identification. The name does not need to be unique.

    Source Database

    Select DMS Database Instance

    Choose whether to use an existing instance as needed.

    • If you use an existing instance, the database information is automatically filled in. You do not need to enter it again.

    • If you do not use an existing instance, enter the database information below.

    Database Type

    Select MySQL.

    Access Method

    Select Alibaba Cloud Instance.

    Instance Region

    Select the region of the source ApsaraDB RDS for MySQL instance.

    Cross-account

    Specifies whether the source database belongs to a different Alibaba Cloud account. In this example, select No.

    RDS Instance ID

    Select the ID of the source ApsaraDB RDS for MySQL instance.

    Database Account

    Enter the database account of the source ApsaraDB RDS for MySQL instance. For more information about the required permissions, see Permissions required for database accounts.

    Database Password

    Enter the password for the database account.

    Connection Method

    Select Non-encrypted or SSL-encrypted based on your database requirements. If you set this parameter to SSL-encrypted, you must enable SSL encryption for the RDS for MySQL instance beforehand. For more information, see Quickly enable SSL encryption using a cloud certificate.

    Destination Database

    Select DMS Database Instance

    Choose whether to use an existing instance as needed.

    • If you use an existing instance, the database information is automatically filled in. You do not need to enter it again.

    • If you do not use an existing instance, enter the database information below.

    Database Type

    Select Oracle.

    Access Method

    Select Self-managed Database on ECS.

    Note

    If your destination database is a self-managed database, you must perform preparatory work. For more information, see Preparation overview.

    Instance Region

    Select the region of the destination self-managed Oracle instance.

    ECS Instance ID

    Select the ID of the ECS instance hosting the destination self-managed Oracle database.

    Port Number

    Enter the service port of the destination self-managed Oracle database. Default value: 1521.

    Oracle Type

    Select the Oracle instance type. In this example, select RAC or PDB Instance.

    • Non-RAC Instance: If you select this option, you must specify the SID.

    • RAC or PDB Instance: If you select this option, you must specify the Service Name.

    Database Account

    Enter the database account of the destination self-managed Oracle instance.

    Database Password

    Enter the password for the database account.

  4. After you complete the configuration, click Test Connectivity and Proceed at the bottom of the page. In the CIDR Blocks of DTS Servers dialog box that appears, click Test Connectivity.

    Note

    Ensure that the IP address segments of the DTS service are 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 DTS server IP addresses to a whitelist.

  5. Configure the task objects.

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

      Parameter

      Description

      Migration Types

      • If you only need to perform a full migration, select both Schema Migration and Full Data Migration.

      • To perform a migration with no downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration.

      Note

      • If you do not select Schema Migration, you must ensure that a database and tables to receive the data exist in the destination database. You can also use the object name mapping feature in the Selected Objects box as needed.

      • If you do not select Incremental Data Migration, do not write new data to the source instance during data migration to ensure data consistency.

      Processing Mode for Existing Destination Tables

      • Precheck and Report Errors: Checks for tables in the destination database with the same names as tables in the source database. The precheck passes if no such tables exist. Otherwise, the precheck fails and the migration task cannot start.

        Note

        If you cannot delete or rename the tables with the same names in the destination database, you can change the names of these tables in the destination database. For more information, see Map table and column names.

      • Ignore Errors and Proceed: Skips the check for tables with the same names in the destination database.

        Warning

        If you select Ignore Errors and Proceed, data inconsistency may occur and expose your business to risks. For example:

        • If a destination record has the same primary key as a source record, and the schemas match:

          • During a full data migration, DTS keeps the destination record and does not migrate the source record.

          • During an incremental data migration, DTS overwrites the destination record with the source record.

        • If the source and destination databases have different schemas, data initialization may fail, resulting in partial data migration or a complete migration failure.

      Case Policy for Destination Object Names

      Configure the case-sensitivity of database names, table names, and column names in the destination instance. By default, DTS default policy is selected. You can also select other options to ensure that the case of object names is consistent with that in the source or destination database. For more information, see Case-sensitivity of object names in the destination instance.

      Source Objects

      In the Source Objects box, click the objects to migrate, and then click Right arrow to move them to the Selected Objects box.

      Note

      The granularity for selecting migration objects is schema, table, and column. If you select only tables or columns as migration objects, other objects such as views, triggers, and stored procedures are not migrated to the destination database.

      Selected Objects

      Right-click a database in the Selected Objects box. On the Edit Schema page, change the Schema Name to the schema of the destination database in your self-managed Oracle database. By default, the schema name is the same as the Database Account. For more information about the object name mapping feature, see Map table and column names.

      Note

      • Using object name mapping can cause migrations to fail for dependent objects.

      • To set a WHERE condition to filter data, right-click the table to be migrated in the Selected Objects section, and set the filter condition in the dialog box that appears. For more information, see Configure filter conditions.

      • To select SQL operations for migration at the database or table level, right-click a migration object in the Selected Objects box and select the required SQL operations in the dialog box.

    2. Click Next: Advanced Settings to configure advanced parameters.

      Parameter

      Description

      Dedicated Cluster for Task Scheduling

      By default, DTS schedules tasks on a shared cluster. You do not need to select one. If you want more stable tasks, you can purchase a dedicated cluster to run DTS migration tasks.

      Retry Time for Failed Connections

      After the migration task starts, if the connection to the source or destination database fails, DTS reports an error and immediately begins to retry the connection. The default retry duration is 720 minutes. You can customize the retry time to a value from 10 to 1440 minutes. We recommend that you set the duration to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified duration, the migration task automatically resumes. Otherwise, the task fails.

      Note

      • For multiple DTS instances that share the same source or destination, the network retry time is determined by the setting of the last created task.

      • Because you are charged for the task during the connection retry period, we recommend that you customize the retry time based on your business needs, or release the DTS instance as soon as possible after the source and destination database instances are released.

      Retry Time for Other Issues

      After the migration task starts, if a non-connectivity issue, such as a DDL or DML execution exception, occurs in the source or destination database, DTS reports an error and immediately begins to retry the operation. The default retry duration is 10 minutes. You can customize the retry time to a value from 1 to 1440 minutes. We recommend that you set the duration to more than 10 minutes. If the related operations succeed within the specified retry duration, the migration task automatically resumes. Otherwise, the task fails.

      Important

      The value of Retry Time for Other Issues must be less than the value of Retry Time for Failed Connections.

      Enable Throttling for Full Data Migration

      During full migration, DTS consumes read and write resources on the source and destination databases, which may increase the database load. If required, you can enable throttling for the full migration task. You can set Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) to reduce the load on the destination database.

      Note

      • This configuration item is available only if you select Full Data Migration for Migration Types.

      • You can also adjust the full migration speed after the migration instance is running.

      Enable Throttling for Incremental Data Migration

      If required, you can also choose to set speed limits for the incremental migration task. You can set RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) to reduce the load on the destination database.

      Note

      • This configuration item is available only if you select Incremental Data Migration for Migration Types.

      • You can also adjust the incremental migration speed after the migration instance is running.

      Environment Tag

      You can select an environment tag to identify the migration instance. In this example, no tag is needed.

      Whether to delete SQL operations on heartbeat tables of forward and reverse tasks

      Choose whether DTS writes heartbeat SQL information to the source database while the instance is running.

      • Yes: Does not write heartbeat SQL information to the source database. The DTS instance may display latency.

      • No: Writes heartbeat SQL information to the source database. This may interfere with source database operations like physical backups and cloning.

      Configure ETL

      Based on your business needs, select whether to configure the ETL feature to process data.

      • Yes: Configures the ETL feature. You must also enter data processing statements in the text box.

      • No: Does not configure the ETL feature.

      Monitoring and Alerting

      Select whether to set alerts and receive alert notifications based on your business needs.

      • No: Does not set an alert.

      • Yes: Configure alerts by setting an alert threshold and an alert contact. If a migration fails or the latency exceeds the threshold, the system sends an alert notification.

    3. Click Next: Data Validation to configure a data validation task.

      For more information about the data validation feature, see Configure data validation.

  6. Save the task and run a precheck.

    • To view the parameters for configuring this instance when you call the API operation, move the pointer over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the bubble that appears.

    • If you do not need to view or have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

    Note

    • Before the migration task starts, DTS performs a precheck. The task starts only after it passes the precheck.

    • If the precheck fails, click View Details next to the failed check item, fix the issue based on the prompt, and then run the precheck again.

    • If a warning is reported during the precheck:

      • For check items that cannot be ignored, click View Details next to the failed item, fix the issue based on the prompt, and then run the precheck again.

      • For check items that can be ignored, you can click Confirm Alert Details, Ignore, OK, and Precheck Again to skip the alert item and run the precheck again. If you choose to ignore a warning, it may cause issues such as data inconsistency and pose risks to your business.

  7. Purchase an instance.

    1. When the Success Rate is 100%, click Next: Purchase Instance.

    2. On the Purchase page, select the link specification for the data migration instance. For more information, see the following table.

      Category

      Parameter

      Description

      New Instance Class

      Resource Group Settings

      Select the resource group to which the instance belongs. The default value is default resource group. For more information, see What is Resource Management?

      Instance Class

      DTS provides migration specifications with different performance levels. The link specification affects the migration speed. You can select a specification based on your business scenario. For more information, see Data migration link specifications.

    3. After the configuration is complete, read and select Data Transmission Service (Pay-as-you-go) Service Terms.

    4. Click Buy and Start. In the OK dialog box that appears, click OK.

      You can view the progress of the migration task on the Data Migration Tasks list page.

      Note

      • If the migration task does not include incremental migration, it stops automatically after the full migration is complete. After the task stops, its Status changes to Completed.

      • If the migration task includes incremental migration, it does not stop automatically. The incremental migration task continues to run. While the incremental migration task is running, the Status of the task is Running.

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