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    Data Transmission Service:Synchronize RDS for MySQL to RDS for PostgreSQL

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    Data Transmission Service:Synchronize RDS for MySQL to RDS for PostgreSQL

    Last Updated:Jul 17, 2026

    Data Transmission Service (DTS) supports data synchronization from an ApsaraDB RDS for MySQL instance to an ApsaraDB RDS for PostgreSQL instance.

    Prerequisites

    Usage notes

    Note

    • During schema synchronization, DTS synchronizes foreign keys from the source database to the destination database.

    • During full data synchronization and incremental data synchronization, DTS temporarily disables constraint checks and foreign key cascade operations at the session level. Data inconsistency may occur if cascade update or delete operations are performed on the source database while the task is running.

    Type

    Description

    Source database limits

    • The tables to synchronize must have a primary key or a unique constraint, and the fields must be unique. Otherwise, duplicate data may appear in the destination database.

    • If you synchronize at the table level and need to edit mappings (such as column name mapping), each synchronization task supports up to 1,000 tables. If you exceed this limit, the task fails with an error. To fix this, split the tables across multiple tasks or configure a full-database synchronization task.

    • Binary logs:

      • ApsaraDB RDS for MySQL enables binary logging by default. Ensure that the binlog_row_image parameter is set to full. Otherwise, the precheck fails and the synchronization task cannot start. For instructions, see Configure instance parameters.

        Important

        • If your source instance is a self-managed MySQL database, enable binary logging and set binlog_format to row and binlog_row_image to full.

        • If your self-managed MySQL database is a dual-primary cluster (where both nodes act as primary and secondary), enable the log_slave_updates parameter so DTS can capture all binary log events. For instructions, see Create an account and configure binary logging for a self-managed MySQL database.

      • The local binary logs for an ApsaraDB RDS for MySQL instance must be retained for at least three days (seven days is recommended). For a self-managed MySQL database, retain local binary logs for at least seven days. Otherwise, DTS may fail to retrieve binary logs, causing the task to fail. In extreme cases, this may cause data inconsistency or data loss. Issues caused by binary log retention periods shorter than DTS requires are not covered under the DTS SLA.

        Note

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

    • Do not run DDL operations that change database or table schemas during schema synchronization or full synchronization. Otherwise, the synchronization task fails.

      Note

      During full synchronization, DTS queries the source database. This creates metadata locks that may block DDL operations on the source database.

    • Data generated by changes that do not write to binary logs—such as data restored from physical backups or created by cascade operations—is not synchronized to the destination database.

      Note

      If this occurs, remove the affected database or table from the synchronization objects. Then add it back. You can do this only if your business allows it. For more information, see Modify synchronization objects.

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

      Note

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

    • MySQL compatibility: When DTS synchronizes data from a MySQL-family source database, it relies on the standard MySQL protocol and Binlog format, and behaviors incompatible with standard MySQL are not supported. If your source database claims MySQL compatibility but behaves differently from MySQL (for example, when OceanBase is connected as a source in MySQL mode, the timestamp of the trailing rotate event in the Binlog is 0, which differs from MySQL), the DTS synchronization task may fail.

    Other limits

    • Synchronization object requirements:

      • Only table-level synchronization is supported.

      • DTS does not support synchronizing BIT, VARBIT, GEOMETRY, LINESTRING, POLYGON, ARRAY, UUID, TSQUERY, TSVECTOR, TXID_SNAPSHOT, or POINT data types.

      • DTS does not support synchronizing prefix indexes. If your source database contains prefix indexes, synchronization may fail.

      • DTS does not support synchronizing partitions, views, stored procedures, functions, or triggers.

    • If your source database uses online DDL operations in temporary table mode—including but not limited to multi-table merge scenarios—or adds function-based indexes to unique key columns, data loss or task failure may occur in the destination database.

    • If a primary key or unique key conflict occurs while the task is running:

      • If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database:

        • During full data synchronization, DTS retains the destination record and skips the source record.

        • During incremental synchronization, DTS overwrites the destination record with the source record.

      • If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.

    • Assess the performance of both the source and destination databases before starting synchronization. Run synchronization during off-peak hours. Otherwise, full initialization consumes read and write resources on both databases and may increase database load.

    • Full initialization runs INSERT operations concurrently. This fragments destination tables. After full initialization, the tablespace of the destination instance is larger than that of the source instance.

    • If you synchronize one or more tables—not a full database—do not use tools like pt-online-schema-change to perform online DDL operations on the source tables. Otherwise, synchronization fails.

      You can use Data Management (DMS) to perform online DDL operations. For more information, see Online DDL without locking tables.

    • Do not write data to the destination database except through DTS while synchronization is running. Otherwise, data inconsistency may occur between the source and destination databases. For example, if you use DMS to perform online DDL operations while other data is written to the destination database, data loss may occur.

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

      Note

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

    • For full or incremental data synchronization tasks, if the source tables to be synchronized contain foreign keys, triggers, or event triggers, DTS temporarily sets the session_replication_role parameter to replica at the session level. If the destination database account does not have the required permissions, you must manually set the session_replication_role parameter to replica in the destination database. During this period, if cascade update or delete operations occur in the source database while session_replication_role is set to replica, data inconsistency may occur. After the DTS task is released, change the session_replication_role parameter back to origin.

    • 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 a self-managed MySQL source database:

      • If a primary/secondary switchover occurs in the source database during synchronization, the task fails.

      • DTS calculates latency by comparing the timestamp of the last synchronized record with the current time. If no DML operations run for a long time in the source database, latency reporting may become inaccurate. If latency appears too high, run a DML operation in the source database to update the latency.

        Note

        If you select a full database for synchronization, create a heartbeat table. Update or write to this table every second.

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

      • If your source database is Amazon Aurora MySQL or another clustered MySQL instance, ensure the domain name or IP address used in the task configuration—and its DNS resolution—always points to a read/write (RW) node. Otherwise, synchronization may fail.

    • For an ApsaraDB RDS for MySQL source database:

      • Read-only instances—such as ApsaraDB RDS for MySQL 5.6 read-only instances—that do not record transaction logs cannot serve as source databases.

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

    Billing

    Synchronization type

    Pricing

    Schema synchronization and full data synchronization

    Free of charge.

    Incremental data synchronization

    Charged. For more information, see Billing overview.

    Supported synchronization topologies

    • One-to-one, one-way synchronization

    • One-to-many, one-way synchronization

    • Many-to-one, one-way synchronization

    Supported SQL operations

    Operation type

    SQL statement

    DML

    INSERT, UPDATE, DELETE

    Procedure

    1. Go to the data synchronization task list page in the destination region. You can do this in one of two ways.

      DTS console

      1. Log on to the DTS console.

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

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

      DMS console

      Note

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

      1. Log on to the DMS console.

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

      3. To the right of Data Synchronization Tasks, select the region of the synchronization instance.

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

    3. Configure the source and destination databases.

      Category

      Setting

      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

      Database Type

      Select MySQL.

      Connection Type

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region where the source ApsaraDB RDS for MySQL instance resides.

      Replicate Data Across Alibaba Cloud Accounts

      This example uses synchronization within the same Alibaba Cloud account. Select No.

      RDS Instance ID

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

      Database Account

      Enter the database account for the source ApsaraDB RDS for MySQL instance.

      Database Password

      Enter the password for the specified database account.

      Encryption

      Select Non-encrypted or SSL-encrypted as needed. If you set this to SSL-encrypted, you must enable SSL encryption for the RDS for MySQL instance beforehand. For more information, see Use a cloud certificate to quickly enable SSL link encryption.

      Destination Database

      Database Type

      Select PostgreSQL.

      Connection Type

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region where the destination ApsaraDB RDS for PostgreSQL instance resides.

      Instance ID

      Select the ID of the destination ApsaraDB RDS for PostgreSQL instance.

      Database Name

      Enter the name of the destination database that contains the objects to synchronize in the ApsaraDB RDS for PostgreSQL instance.

      Database Account

      Enter the database account for the destination ApsaraDB RDS for PostgreSQL instance. The account must have owner privileges on the schema. For more information, see Create an account.

      Database Password

      Enter the password for the specified database account.

      Encryption

      Specifies whether to encrypt the connection to the source database. You can configure this parameter based on your business requirements. In this example, Non-encrypted is selected.

      If you want to establish an SSL-encrypted connection to the source database, perform the following steps: Select SSL-encrypted, upload CA Certificate, Client Certificate, and Private Key of Client Certificate as needed, and then specify Private Key Password of Client Certificate.

      Note

      • If you set Encryption to SSL-encrypted for a self-managed PostgreSQL database, you must upload CA Certificate.

      • If you want to use the client certificate, you must upload Client Certificate and Private Key of Client Certificate and specify Private Key Password of Client Certificate.

      • For information about how to configure SSL encryption for an ApsaraDB RDS for PostgreSQL instance, see SSL encryption.

    4. After completing the configuration, click Test Connectivity and Proceed at the bottom of the page.

      Note

      • Ensure that you add the CIDR blocks of the DTS servers (either automatically or manually) to the security settings of both the source and destination databases to allow access. For more information, see Add the IP address whitelist of DTS servers.

      • If the source or destination is a self-managed database (i.e., the Access Method is not Alibaba Cloud Instance), you must also click Test Connectivity in the CIDR Blocks of DTS Servers dialog box.

    5. Configure the task objects.

      1. On the Configure Objects page, specify the objects to synchronize.

        Setting

        Description

        Synchronization Type

        The synchronization types. By default, Incremental Data Synchronization is selected. You must also select Schema Synchronization and Full Data Synchronization. After the precheck is complete, DTS synchronizes the historical data of the selected objects from the source database to the destination cluster. The historical data is the basis for subsequent incremental synchronization.

        Processing Mode for Existing Destination Tables

        • Precheck and Report Errors: Checks for tables with the same names in the destination database. If any tables with the same names are found, an error is reported during the precheck and the data synchronization task does not start. Otherwise, the precheck is successful.

          Note

          If you cannot delete or rename the table with the same name in the destination database, you can map it to a different name in the destination. For more information, see Object name mapping.

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

          Warning

          Selecting Ignore Errors and Proceed may cause data inconsistency and put your business at risk. For example:

          • If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database:

            • During full data synchronization, DTS retains the destination record and skips the source record.

            • During incremental synchronization, DTS overwrites the destination record with the source record.

          • If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.

        Case Policy for Destination Object Names

        Configure the case-sensitivity policy for database, table, and column names in the destination instance. By default, the DTS default policy is selected. You can also choose to use the default policy of the source or destination database. For more information, see Case policy for destination object names.

        Source Objects

        In the Source Objects box, click the objects, and then click 向右 to move them to the Selected Objects box.

        Note

        You can select objects at the database, table, or column level. If you select only tables or columns, DTS does not synchronize other object types (such as views, triggers, and stored procedures).

        Selected Objects

        • To rename a single object in the destination instance, right-click the object in the Selected Objects box. For more information, see Map a single object name.

        • To rename multiple objects in bulk, click Batch Edit in the upper-right corner of the Selected Objects box. For more information, see Map multiple object names in bulk.

        Note

        • If you use object name mapping, other objects that depend on the mapped object may fail to synchronize.

        • To filter data by using a WHERE clause, right-click the target table in the Selected Objects box and set the filter conditions in the dialog box that appears. For more information, see Configure filter conditions.

        • The Timestamp data type is supported. If a time field in the source database has a value of 0, DTS automatically converts it to null in the destination database.

      2. Click Next: Advanced Settings.

        Setting

        Description

        Dedicated Cluster for Task Scheduling

        By default, DTS uses a shared cluster for tasks, so you do not need to make a selection. For greater task stability, you can purchase a dedicated cluster to run the DTS synchronization task. For more information, see What is a DTS dedicated cluster?.

        Retry Time for Failed Connections

        If the connection to the source or destination database fails after the synchronization task starts, 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 1,440 minutes. We recommend a duration of 30 minutes or more. If the connection is restored within this period, the task resumes automatically. Otherwise, the task fails.

        Note

        • If multiple DTS instances (e.g., Instance A and B) share a source or destination, DTS uses the shortest configured retry duration (e.g., 30 minutes for A, 60 for B, so 30 minutes is used) for all instances.

        • DTS charges for task runtime during connection retries. Set a custom duration based on your business needs, or release the DTS instance promptly after you release the source/destination instances.

        Retry Time for Other Issues

        If a non-connection issue (e.g., a DDL or DML execution error) occurs, DTS reports an error and immediately retries the operation. The default retry duration is 10 minutes. You can also customize the retry time to a value from 1 to 1,440 minutes. We recommend a duration of 10 minutes or more. If the related operations succeed within the set retry time, the synchronization task automatically resumes. Otherwise, the task fails.

        Important

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

        Enable Throttling for Full Data Synchronization

        During full data synchronization, DTS consumes read and write resources from the source and destination databases, which can increase their load. To mitigate pressure on the destination database, you can limit the migration rate by setting Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s).

        Note

        Enable Throttling for Incremental Data Synchronization

        You can also limit the incremental synchronization rate to reduce pressure on the destination database by setting RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s).

        Environment Tag

        Select an environment tag to identify the instance. In this example, no selection is required.

        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

        Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values:

        Monitoring and Alerting

        Choose whether to set up alerts. If the synchronization fails or the latency exceeds the specified threshold, DTS sends a notification to the alert contacts.

      3. Click Data Verification to configure a data verification task.

        To use the data verification feature, see Configure data verification.

    6. Save the task and perform a precheck.

      • To view the parameters for configuring this instance via an API operation, hover over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the tooltip.

      • If you have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

      Note

      • Before a synchronization task starts, DTS performs a precheck. You can start the task only if the precheck passes.

      • If the precheck fails, click View Details next to the failed item, fix the issue as prompted, and then rerun the precheck.

      • If the precheck generates warnings:

        • For non-ignorable warning, click View Details next to the item, fix the issue as prompted, and run the precheck again.

        • For ignorable warnings, you can bypass them by clicking Confirm Alert Details, then Ignore, and then OK. Finally, click Precheck Again to skip the warning and run the precheck again. Ignoring precheck warnings may lead to data inconsistencies and other business risks. Proceed with caution.

    7. Purchase the instance.

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

      2. On the Purchase page, select the billing method and link specifications for the data synchronization instance. For more information, see the following table.

        Category

        Parameter

        Description

        New Instance Class

        Billing Method

        • Subscription: You pay upfront for a specific duration. This is cost-effective for long-term, continuous tasks.

        • Pay-as-you-go: You are billed hourly for actual usage. This is ideal for short-term or test tasks, as you can release the instance at any time to save costs.

        Resource Group Settings

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

        Instance Class

        DTS offers synchronization specifications at different performance levels that affect the synchronization rate. Select a specification based on your business requirements. For more information, see Data synchronization link specifications.

        Subscription Duration

        In subscription mode, select the duration and quantity of the instance. Monthly options range from 1 to 9 months. Yearly options include 1, 2, 3, or 5 years.

        Note

        This option appears only when the billing method is Subscription.

      3. Read and select the checkbox for Data Transmission Service (Pay-as-you-go) Service Terms.

      4. Click Buy and Start, and then click OK in the OK dialog box.

        You can monitor the task progress on the data synchronization page.