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    Data Transmission Service:Synchronize self-managed PostgreSQL to PolarDB for PostgreSQL (Compatible with Oracle)

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    Data Transmission Service:Synchronize self-managed PostgreSQL to PolarDB for PostgreSQL (Compatible with Oracle)

    Last Updated:Jul 10, 2026

    You can use Data Transmission Service (DTS) to synchronize data from a self-managed PostgreSQL database to PolarDB for PostgreSQL (Compatible with Oracle).

    Prerequisites

    • You have a source self-managed PostgreSQL database and a destination PolarDB for PostgreSQL (Compatible with Oracle) cluster.

      Note

    • The destination PolarDB for PostgreSQL (Compatible with Oracle) cluster must have more storage space than the source self-managed PostgreSQL database.

    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

    Limits on the source database

    • Tables that you synchronize must have a primary key or a unique constraint. Otherwise, duplicate data can occur in the destination database.

      Note

      If you create the destination table manually (without selecting Synchronization Types as the Schema Synchronization), you must ensure that the destination table has the same primary key or non-null unique constraint as the source table. Otherwise, duplicate data may occur in the destination database.

    • If you synchronize data at the table level and need to edit the objects, such as mapping table or column names, for more than 5,000 tables in a single data synchronization task, we recommend splitting them into multiple tasks or configuring a task to synchronize the entire database. Otherwise, the task may fail upon submission.

    • The name of the database to be synchronized cannot contain hyphens (-), for example, dts-testdata.

    • Write-ahead logging (WAL):

      • You must enable WAL by setting the wal_level parameter to logical.

      • For an incremental data synchronization task, DTS requires that the WAL of the source database be retained for more than 24 hours. For a task that performs both full and incremental data synchronization, the WAL must be retained for at least seven days. You can change the retention period to more than 24 hours after the full data synchronization is complete. If a task fails because DTS cannot obtain the WAL due to a shorter retention period, the failure may lead to data inconsistency or loss in extreme cases. Issues caused by an insufficient WAL retention period are not covered by the DTS Service Level Agreement (SLA).

    • A primary/secondary switchover on the source self-managed PostgreSQL database causes the data synchronization task to fail.

    • Ensure that the values of the max_wal_senders and max_replication_slots parameters are both greater than the sum of the number of used replication slots in the database and the number of DTS instances that you want to create with this database as the source.

    • If the source database has long-running transactions and the instance is configured for incremental data synchronization, the write-ahead logging (WAL) data generated before these transactions are committed cannot be cleared. This can cause WAL data to accumulate and may lead to insufficient disk space on the source database.

    • If the source is a Cloud SQL for PostgreSQL instance, you must enter a database account that has the cloudsqlsuperuser permission in the Database Account field. When you select the objects to be synchronized, you must select objects that this account is authorized to manage, or grant the OWNER permission on the objects to this account. For example, run the GRANT <owner_of_objects> TO <source_account_for_task> command to allow the account to perform operations as the owner of the objects.

      Note

      An account that has the cloudsqlsuperuser permission cannot manage data owned by other accounts that also have the cloudsqlsuperuser permission.

    • Due to the inherent limitations of logical subscriptions in the source database, if a single data record to be synchronized exceeds 256 MB after an incremental change, the synchronization instance will fail and must be reconfigured.

    • 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.

    • If you perform a major version upgrade on the source database while a synchronization instance is running, it will fail and must be reconfigured.

    Other limits

    • For full or incremental data synchronization, if the synchronized tables 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 this permission, you must manually set the session_replication_role parameter to replica in the destination database. During this period (while session_replication_role is set to replica), data inconsistency may occur if cascade update or delete operations occur in the source database. After the DTS data synchronization task is released, you can change the session_replication_role parameter back to origin.

    • If a table to be synchronized contains a SERIAL type column, the source database automatically creates a sequence for that column. Therefore, when you configure Source Objects, if you select Schema Synchronization for Synchronization Types, we recommend that you also select Sequence or synchronize the entire schema. Otherwise, the synchronization instance may fail.

    • A single data synchronization task can synchronize only one database. To synchronize multiple databases, you must configure a separate task for each.

    • DTS does not support synchronizing TimescaleDB plug-in tables, tables with cross-schema inheritance, or tables with expression-based unique indexes.

    • Schemas created by installing plug-ins are not supported for synchronization. You cannot retrieve information about these schemas in the console when you configure a task.

    • In the following three scenarios, you must run the ALTER TABLE schema.table REPLICA IDENTITY FULL; command on the source tables before writing data to them to ensure data consistency. Do not perform table-locking operations while this command is running to prevent deadlocks. If you skip this check during the precheck, DTS automatically runs this command during instance initialization.

      • When the instance runs for the first time.

      • When you select objects at the schema level, and a new table is created in the schema or a table is rebuilt by using the RENAME command.

      • When you use the feature to modify synchronization objects.

      Note

      • Replace schema and table in the command with the names of the schema and table to be synchronized.

      • Perform this operation during off-peak hours.

    • DTS verifies data content but does not support verifying metadata such as sequences. You must verify such metadata yourself.

    • After you switch your business to the destination database, sequences do not automatically continue from the maximum value of the corresponding sequences in the source database. Before the switchover, you must update the sequence values in the destination database. For more information, see Update the sequence values in the destination database.

    • DTS creates the following temporary tables in the source database to obtain DDL statements for incremental data, the schema of incremental tables, and heartbeat information. Do not delete these temporary tables during synchronization. Otherwise, the DTS task may fail. The temporary tables are automatically deleted after the DTS instance is released.

      public.dts_pg_class, public.dts_pg_attribute, public.dts_pg_type, public.dts_pg_enum, public.dts_postgres_heartbeat, public.dts_ddl_command, public.dts_args_session, and public.aliyun_dts_instance.

    • To ensure the accuracy of the displayed synchronization latency, DTS adds a heartbeat table named dts_postgres_heartbeat to the source database.

    • During data synchronization, DTS creates a replication slot with the dts_sync_ prefix in the source database to replicate data. This replication slot allows DTS to obtain incremental logs generated within the last 15 minutes from the source database. When a data synchronization task fails or the instance is released, DTS attempts to automatically remove this replication slot.

      Note

      • If you change the password of the source database account or delete the IP whitelist for DTS during data synchronization, the replication slot will not be cleaned up automatically. Manually clean up the replication slot in the source database to prevent it from consuming disk space and making the source database unavailable.

      • If the source database fails over, log on to the standby database to perform the cleanup manually.

      Run the SQL statement SELECT * FROM pg_replication_slots; to view all replication slots in the source database. In the results, the DTS replication slot is the record where the slot_name value starts with dts_sync_ and the active value is true.

    • Before you start data synchronization, evaluate the performance of the source and destination databases. Perform the synchronization during off-peak hours. Full data synchronization consumes read and write resources on both databases, which can increase their load.

    • Full data synchronization performs concurrent INSERT operations, which can cause table fragmentation in the destination database. As a result, the tablespace of the destination instance will be larger than that of the source instance after full data synchronization is complete.

    • For table-level data synchronization, if no data from sources other than DTS is written to the destination database, you can use DMS to perform online DDL changes. For more information, see Change schemas without locking tables.

    • During DTS synchronization, do not write data to the destination database from any other source. This can cause data inconsistency. For example, if you use Data Management (DMS) to perform online DDL changes while data is being written from other sources, it may cause data loss in the destination database.

    • 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.

    • When you synchronize partitioned tables, you must include both the parent table and its child partitions as synchronization objects. Otherwise, data in the partitioned table may become inconsistent.

      Important

      • The parent table of a PostgreSQL partitioned table does not store data directly. All data is stored in the child partitions. A data synchronization task must include the parent table and all its child partitions. Otherwise, data from the child partitions may be missed, causing data inconsistency between the source and destination.

      • Synchronization of partitioned tables and inheritance tables (parent-child tables) across different databases is not supported. Ensure that the partitioned tables and all their partitions, and the parent tables and all their child tables, are in the same database.

    Pricing

    Synchronization type

    Fees

    Schema synchronization and full synchronization

    Free.

    Incremental synchronization

    Fees apply. See billing overview.

    Synchronization topologies

    • One-way one-to-one synchronization

    • One-way one-to-many synchronization

    • One-way cascade synchronization

    • One-way many-to-one synchronization

    For more information about synchronization topologies, see Synchronization topologies.

    Supported objects

    • SCHEMA, TABLE.

      Note

      This includes PRIMARY KEY, UNIQUE KEY, FOREIGN KEY, DATATYPE (built-in data types), and DEFAULT CONSTRAINT.

    • VIEW, PROCEDURE (requires PostgreSQL 11 or later), FUNCTION, RULE, SEQUENCE, EXTENSION, TRIGGER, AGGREGATE, INDEX, OPERATOR, DOMAIN.

    Supported SQL operations

    Operation type

    SQL operation

    DML

    INSERT, UPDATE, DELETE

    DDL

    • DDL synchronization is supported only for data synchronization tasks created after .

      Important

    • The synchronization task supports the following DDL operations, provided the source database account is a high-privilege account and the self-managed PostgreSQL database has minor version 20210228 or later.

      • CREATE TABLE, DROP TABLE

      • ALTER TABLE (including RENAME TABLE, ADD COLUMN, ADD COLUMN DEFAULT, ALTER COLUMN TYPE, DROP COLUMN, ADD CONSTRAINT, ADD CONSTRAINT CHECK, and ALTER COLUMN DROP DEFAULT)

      • TRUNCATE TABLE (requires the source database to be PostgreSQL 11 or later)

      • CREATE INDEX ON TABLE

      Important

      • DDL statements that include additional information, such as CASCADE or RESTRICT, are not supported.

      • DDL statements in a session that uses the SET session_replication_role = replica command are not synchronized.

      • DDL statements executed by calling a FUNCTION are not supported.

      • If a commit contains both DML and DDL operations, the DDL operations are not synchronized.

      • If a commit contains DDL operations on objects that are not being synchronized, those operations are not synchronized.

      • DDL statements executed directly within a plugin through the SPI (Server Programming Interface) are not supported.

    Permission requirements for database accounts

    Database

    Required permissions

    Account creation and authorization

    Self-managed PostgreSQL

    superuser permission.

    Use the CREATE USER statement and manage user permissions.

    PolarDB for PostgreSQL (Oracle-compatible)

    owner permission on the database.

    Create a database account.

    Note

    You specify the database owner when you create the database.

    Preparation

    Note

    The following steps apply to Linux systems.

    Complete the following preparations for all versions of self-managed PostgreSQL.

    1. Log on to the server that hosts the self-managed PostgreSQL database.

    2. Run the following command to check the number of replication slots that are currently in use:

      select count(1) from pg_replication_slots;

    3. Modify the postgresql.conf configuration file: set wal_level to logical, and make sure that both max_wal_senders and max_replication_slots are greater than the sum of replication slots already in use and the number of DTS instances you plan to create with this self-managed PostgreSQL database as the source.

      # - Settings -
wal_level = logical			# minimal, replica, or logical
					# (change requires restart)
......
# - Sending Server(s) -
# Set these on the master and on any standby that will send replication data.
max_wal_senders = 10		# max number of walsender processes
				# (change requires restart)
#wal_keep_segments = 0		# in logfile segments, 16MB each; 0 disables
#wal_sender_timeout = 60s	# in milliseconds; 0 disables
max_replication_slots = 10	# max number of replication slots
				# (change requires restart)
      Note

      After you modify the configuration file, restart the self-managed PostgreSQL database to apply the changes.

    4. Add the DTS IP addresses to the pg_hba.conf configuration file of the self-managed PostgreSQL database. You only need to add the DTS IP address range for the region where the destination database resides. For more information, see Whitelist DTS server IP addresses.

      Note

      • After you modify the configuration file, run the SELECT pg_reload_conf(); command or restart the self-managed PostgreSQL database to apply the changes.

      • For more information about the configuration file, see The pg_hba.conf File. If you have already set the trusted address to 0.0.0.0/0 (as shown in the following sample), you can skip this step.

      # "local" is for Unix domain socket connections only
local   all             all                                     trust
# IPv4 local connections:
host    all             all             0.0.0.0/0               md5
# IPv6 local connections:
host    all             all             ::1/128                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     postgres                                trust
host    replication     postgres        0.0.0.0/0               md5

    5. In the destination database instance, create the databases and schemas that correspond to the objects you plan to synchronize.

    If your self-managed PostgreSQL version is between 9.4.8 and 10.0, you must also complete the following preparations.

    1. Download the PostgreSQL source code, then compile and install it.

      1. Log on to the server that hosts the self-managed PostgreSQL database.

      2. Based on the version of the source self-managed PostgreSQL database, download the source code of the matching version from the PostgreSQL official website.

      3. Run the sudo ./configure, sudo make, and sudo make install commands in sequence to configure, compile, and install the source code.

        Important

        • When you compile and install PostgreSQL, the operating system version of PostgreSQL must match the GCC (GNU Compiler Collection) version.

        • If sudo ./configure fails, adjust the command based on the error message. For example, if the error is readline library not found. Use --without-readline to disable readline support., change the command to sudo ./configure --without-readline.

        • If you install PostgreSQL in another way, you must compile ali_decoding in a test environment that has the same operating system version and GCC version.

    2. Download the ali_decoding plug-in provided by DTS, then compile and install it.

      1. Download ali_decoding.

      2. Copy the entire ali_decoding directory to the contrib directory of the compiled and installed PostgreSQL.

        total 1068
-rw-r--r--  1 1107 1107    384 Sep 27 2016 aclocal.m4
drwxrwxrwx  2 1107 1107   4096 Sep 27 2016 config
-rw-r--r--  1 root root 374806 Sep  7 10:10 config.log
-rwxr-xr-x  1 root root  39032 Sep  7 10:10 config.status
-rwxr-xr-x  1 1107 1107 471157 Sep 27 2016 configure
-rw-r--r--  1 1107 1107  75195 Sep 27 2016 configure.in
drwxrwxrwx 56 1107 1107   4096 Sep  7 10:28 contrib
-rw-r--r--  1 1107 1107   1192 Sep 27 2016 COPYRIGHT
drwxrwxrwx  3 1107 1107   4096 Sep 27 2016 doc
-rw-r--r--  1 root root   3638 Sep  7 10:10 GNUmakefile
-rw-r--r--  1 1107 1107   3638 Sep 27 2016 GNUmakefile.in
-rw-r--r--  1 1107 1107    283 Sep 27 2016 HISTORY
-rw-r--r--  1 1107 1107  75065 Sep 27 2016 INSTALL
-rw-r--r--  1 1107 1107   1489 Sep 27 2016 Makefile
-rw-r--r--  1 1107 1107   1209 Sep 27 2016 README
drwxrwxrwx 16 1107 1107   4096 Sep 27 2016 src

      3. Go to the ali_decoding directory and replace the content of the Makefile with the following content:

        # contrib/ali_decoding/Makefile
MODULE_big = ali_decoding
MODULES = ali_decoding
OBJS    = ali_decoding.o
DATA = ali_decoding--0.0.1.sql ali_decoding--unpackaged--0.0.1.sql
EXTENSION = ali_decoding
NAME = ali_decoding
#subdir = contrib/ali_decoding
#top_builddir = ../..
#include $(top_builddir)/src/Makefile.global
#include $(top_srcdir)/contrib/contrib-global.mk
#PG_CONFIG = /usr/pgsql-9.6/bin/pg_config
#pgsql_lib_dir := $(shell $(PG_CONFIG) --libdir)
#PGXS := $(shell $(PG_CONFIG) --pgxs)
#include $(PGXS)
# Use the following for source installation
ifdef USE_PGXS
PG_CONFIG = pg_config
PGXS := $(shell $(PG_CONFIG) --pgxs)
include $(PGXS)
else
subdir = contrib/ali_decoding
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
include $(top_srcdir)/contrib/contrib-global.mk
endif

      4. Go to the ali_decoding directory and run the sudo make and sudo make install commands in sequence to compile ali_decoding and generate the files required to install ali_decoding.

      5. Copy the following files to the specified locations.

        /usr/bin/install -c -m 755  ali_decoding.so '/usr/local/pgsql/lib/ali_decoding.so'
/usr/bin/install -c -m 644 ./ali_decoding.control '/usr/local/pgsql/share/extension/'
/usr/bin/install -c -m 644 ./ali_decoding--0.0.1.sql ./ali_decoding--unpackaged--0.0.1.sql  '/usr/local/pgsql/share/extension/'
/usr/bin/install -c -m 755  ali_decoding.so '/usr/local/pgsql/lib/'

    3. In the destination database instance, create the databases and schemas that correspond to the objects you plan to synchronize.

    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

      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 Existing Connection

      • Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured.

        Note

        In the DMS console, this configuration item is Select a DMS database instance.

      • If you have not registered the database instance or do not need to use a registered instance, manually configure the database information below.

      Database Type

      Select PostgreSQL.

      Connection Type

      Select Cloud Enterprise Network (CEN).

      Instance Region

      Select the region where the self-managed PostgreSQL database resides.

      Cross-account

      If you synchronize data within the same Alibaba Cloud account, select No.

      Connected VPC

      Select the VPC that is connected to the self-managed PostgreSQL database.

      IP address

      Enter the server IP address of the self-managed PostgreSQL database.

      Port

      Enter the port number used by the self-managed PostgreSQL database. The default value is 5432.

      Database Name

      Enter the name of the database that contains the objects to be synchronized.

      Database Account

      Enter the database account for the self-managed PostgreSQL database. For information about the required permissions, see Database account permissions.

      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.

      Destination Database

      Select Existing Connection

      • Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured.

        Note

        In the DMS console, this configuration item is Select a DMS database instance.

      • If you have not registered the database instance or do not need to use a registered instance, manually configure the database information below.

      Database Type

      Select PolarDB (Compatible with Oracle).

      Connection Type

      Select Express Connect, VPN Gateway, or Smart Access Gateway.

      Instance Region

      Select the region where the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster resides.

      Connected VPC

      Select the VPC that is connected to the PolarDB for PostgreSQL (Compatible with Oracle) cluster.

      Domain Name or IP Address

      Enter the endpoint of the primary node in the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster.

      Note

      You can run the ping command on your computer to get the IP address for the direct connection endpoint of the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster.

      Port

      Enter the port number used by the destination database. The default value is 1521.

      Database Name

      Enter the name of the destination database that contains the objects to be synchronized in the PolarDB for PostgreSQL (Compatible with Oracle) instance.

      Database Account

      Enter the database account for the destination PolarDB for PostgreSQL (Compatible with Oracle) instance. For information about the required permissions, see Database account permissions.

      Database Password

      Enter the password for the specified database account.

    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.

        Parameter

        Description

        Synchronization Types

        DTS always selects Incremental Data Synchronization. By default, you must also select Schema Synchronization and Full Data Synchronization. After the precheck, DTS initializes the destination cluster with the full data of the selected source objects, which serves as the baseline for subsequent incremental synchronization.

        Processing Mode of Conflicting 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.

        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 synchronization objects at the schema or table level. If you select tables, other objects such as views, triggers, and stored procedures are not synchronized to the destination database.

        • If the tables to be synchronized contain columns of the SERIAL type and you select Synchronization Types that includes Schema Synchronization, we recommend that you also select Sequence or synchronize the entire schema.

        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

        • To select the SQL operations to synchronize for a specific database or table, right-click the object in the Selected Objects box and select the desired operations in the dialog box that appears.

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

      2. Click Next: Advanced Settings.

        Parameter

        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

        You can select an environment tag to identify the instance. This parameter is optional. You can leave it unspecified for this example.

        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.