Migrate data from a self-managed PostgreSQL database to PolarDB for PostgreSQL - Data Transmission Service

This topic describes how to migrate data from a self-managed PostgreSQL database to a PolarDB for PostgreSQL cluster using Data Transmission Service (DTS).

Prerequisites

You have created a destination PolarDB for PostgreSQL database cluster. For more information, see Create a PolarDB for PostgreSQL cluster.
Note
For information about the supported versions of the source and destination databases, see Overview of data migration scenarios.
The storage space of the destination PolarDB for PostgreSQL cluster must be larger than the storage space that is used by the source self-managed PostgreSQL instance.

Precautions

Note

During schema migration, DTS migrates foreign keys from the source database to the destination database.
During full data migration and incremental data migration, DTS temporarily disables the constraint check and cascade operations on foreign keys at the session level. If you perform the cascade update and delete operations on the source database during data migration, data inconsistency may occur.

Category	Description
Limits on the source database	The server that hosts the source database must have sufficient outbound bandwidth. Otherwise, the data migration speed is affected. The tables to be migrated must have a primary key or a UNIQUE constraint, and the fields in the constraint must be unique. Otherwise, duplicate data may appear in the destination database. Note If the target table is not created by DTS (the Schema Migration option is not selected for Migration Types), you must ensure that this table has the same primary key or a non-null UNIQUE constraint as the table to be migrated in the source database. Otherwise, duplicate data may appear in the target database. The name of the database to be migrated cannot contain hyphens (-). For example, dts-testdata. If you migrate objects at the table level and need to edit them, such as by mapping table or column names, a single data migration task supports a maximum of 1,000 tables. If you exceed this limit, a request error is reported after you submit the task. In this case, split the tables into multiple migration tasks, or configure a task to migrate the entire database. For incremental migration, note the following requirements for write-ahead log (WAL) files: Set the wal_level parameter to logical. For an incremental migration task, DTS requires the source database to retain WAL files for more than 24 hours. For a task that includes both full and incremental migration, DTS requires the source database to retain WAL files for at least seven days. After the full migration is complete, you can change the retention period to more than 24 hours. If the retention period is too short, the task may fail because DTS cannot obtain the required WAL files. In extreme cases, this can cause data inconsistency or data loss. Problems caused by a log retention period that is shorter than required are not covered by the DTS Service-Level Agreement (SLA). Limits on operations in the source database: If you perform a primary/secondary switchover on the self-managed PostgreSQL database, the migration task fails. During full data migration, do not perform DDL operations to change the database or table schema. Otherwise, the data migration task fails. Due to the limits on logical subscriptions in the source database, if a single piece of data to be migrated from the source database exceeds 256 MB after an incremental change during the running of a migration instance that includes an incremental task, the migration instance may fail and cannot be recovered. You need to reconfigure the migration instance. If you perform only full data migration, do not write new data to the source database. Otherwise, data in the source and destination databases will be inconsistent. To maintain real-time data consistency, select both full data migration and incremental data migration. If the source database has long-running transactions and the task includes incremental migration, the WAL files generated before the transactions are committed may accumulate. This can cause the disk space of the source database to become insufficient. When the source instance is Google Cloud Platform Cloud SQL for PostgreSQL, you must specify an account that has the `cloudsqlsuperuser` permission for the Database Account of the source database. When you select the objects to migrate, you must select objects that this account has permission to manage, or grant the Owner permission on the objects to be migrated to this account (for example, by running the `GRANT <owner_of_the_object_to_be_migrated> TO <source_database_account_used_by_the_task>` command to allow this account to perform operations as the owner of the objects). Note An account with cloudsqlsuperuser permissions cannot manage data whose owner is another account with cloudsqlsuperuser permissions. If the source database undergoes a major version upgrade while the migration instance is running, the migration instance will fail and cannot be recovered. You need to reconfigure the migration instance.
Other limits	If the migration instance includes an incremental data migration task, you must run the `ALTER TABLE schema.table REPLICA IDENTITY FULL;` command on the table to be migrated in the source database before you write data to it in the following two scenarios. This ensures data consistency for the table migration. During the execution of this command, we recommend that you do not perform table locking operations. Otherwise, the table will be locked. If you skip the relevant check in the precheck, DTS automatically runs this command when the instance is initialized. When the instance runs for the first time. When the migration object granularity is Schema, and a new table is created in the schema to be migrated or a table to be migrated is rebuilt using the RENAME command. Note In the command, replace `schema` and `table` with the schema name and table name of the data to be migrated. We recommend that you perform this operation during off-peak hours. If a table to be migrated contains a field of the SERIAL type, the source database automatically creates a Sequence for the field. Therefore, when you configure the Source Objects, if the Migration Types is set to Schema Migration, we recommend that you also select Sequence or migrate the entire schema. Otherwise, the migration instance may fail. For a full or incremental migration task, if the tables to be migrated in the source database contain foreign keys, triggers, or event triggers, the handling of the `session_replication_role` parameter depends on the permissions of the destination account. If the destination database account is a privileged account, DTS temporarily sets the parameter to `replica` at the session level during the migration. If the account does not have this permission, you must manually set the `session_replication_role` parameter to `replica` for the destination database. While this parameter is set to `replica`, cascading update or delete operations in the source database may cause data inconsistency. After the DTS migration task is released, you can change the value of the `session_replication_role` parameter back to `origin`. DTS creates the following temporary tables in the source database to obtain the DDL statements of incremental data, the schemas of incremental tables, and the heartbeat information. During data migration, do not delete temporary tables in the source database. Otherwise, the DTS task may become abnormal. After the DTS instance is released, temporary tables are automatically deleted. `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 latency for incremental data migration, DTS creates a heartbeat table named `dts_postgres_heartbeat` in the source database. During incremental data migration, DTS creates a replication slot prefixed with `dts_sync_` in the source database to replicate data. Using this replication slot, DTS can retrieve incremental logs from the source database from the last 15 minutes. Note If the data migration task is released or fails, DTS automatically clears the replication slot. If a primary/secondary switchover occurs on the RDS for PostgreSQL instance, you must log on to the secondary database to manually clear the replication slot. A data migration task can migrate data from only one database. To migrate data from multiple databases, you must create a data migration task for each database. DTS does not support migrating TimescaleDB extension tables or tables with cross-schema inheritance relationships. Before migrating data, evaluate the performance of the source and destination databases. Migrate data during off-peak hours. During full data migration, DTS consumes read and write resources on both the source and destination databases. This may increase the database server load. Full data migration involves concurrent INSERT operations, which cause fragmentation in the destination database tables. After the full migration is complete, the storage space used by the tables in the destination database is larger than that in the source database. Confirm that the migration precision for FLOAT or DOUBLE columns meets your business requirements. DTS reads the values from these columns using the `ROUND(COLUMN,PRECISION)` function. If you do not specify a precision, DTS uses a precision of 38 digits for FLOAT and 308 digits for DOUBLE. DTS attempts to resume data migration tasks that failed within the last seven days. Before you switch your business to the destination instance, stop or release the task. You can also use the `revoke` command to revoke the write permissions from the account that DTS uses to access the destination instance. This prevents the source data from overwriting the destination data if the task is automatically resumed. DTS validates data content but does not support validation for metadata, such as Sequences. You must validate the metadata yourself. After you switch your business to the destination instance, the newly written sequence does not increment from the maximum value of the sequence in the source database. You need to update the sequence value in the destination database before the business switchover. For more information, see Update the sequence value in the destination database. If an instance fails, DTS helpdesk will try to recover the instance within 8 hours. During the recovery process, operations such as restarting the instance and adjusting parameters may be performed. Note When parameters are adjusted, only the parameters of the DTS instance are modified. The parameters of the database are not modified. The parameters that may be modified include but are not limited to those described in Modify instance parameters. When migrating partitioned tables, include both the child partitions and the parent table as synchronization objects. Otherwise, data inconsistency may occur for the partitioned table. Note In PostgreSQL, the parent table of a partitioned table does not store data directly. All data is stored in the child partitions. The synchronization task must include the parent table and all its child partitions. Otherwise, data from the child tables might not be synchronized, which leads to data inconsistency between the source and destination.

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 selected objects from the source database to the destination database.
Full data migration
DTS migrates the historical data of required objects from the source database to the destination database.
Incremental data migration
After full data migration is complete, DTS migrates incremental data from the source database to the destination database. Incremental data migration allows data to be migrated smoothly without interrupting the services of self-managed applications during data migration.

Supported objects to be migrated

SCHEMA and TABLE.
Note
Including PRIMARY KEY, UNIQUE KEY, FOREIGN KEY, DATATYPE (built-in data type), and DEFAULT CONSTRAINT.
VIEW, PROCEDURE (PostgreSQL V11 or later.), FUNCTION, RULE, SEQUENCE, EXTENSION, TRIGGER, AGGREGATE, INDEX, OPERATOR, and DOMAIN.

SQL operations that support incremental migration

Operation type	SQL statement
DML	INSERT, UPDATE, and DELETE
DDL	DDL operations can be migrated only in the data migration tasks that are created after October 1, 2020. Important To use a data migration task created before May 12, 2023 to migrate DDL operations, you must create a trigger and a function in the source database to capture DDL information before you configure the data migration task. For more information, see Use triggers and functions to implement incremental DDL migration for PostgreSQL databases. Incremental data migration does not support data of the BIT type. The database account of the source database must be a privileged account. DTS supports the following DDL statements in data migration tasks: CREATE TABLE and 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 (The database engine version of the source PolarDB for PostgreSQL cluster must be PostgreSQL V11 or later.) CREATE INDEX ON TABLE Important You cannot migrate additional information of DDL statements, such as CASCADE or RESTRICT. You cannot migrate the DDL statements from a session in which the `SET session_replication_role = replica` statement is executed. You cannot migrate DDL statements that are executed by invoking functions. If the SQL statements submitted by the source database at a time contain both DML and DDL statements, DTS does not migrate the DDL statements. If the SQL statements submitted by the source database at a time contain DDL statements that are not to be migrated, DTS does not migrate the DDL statements. The CREATE SEQUENCE statement is not supported.

Permissions required for database accounts

Database	Schema migration	Full migration	Incremental migration
Self-managed PostgreSQL database	USAGE permission on pg_catalog	Permissions for the SELECT statement on the objects to migrate	Superuser permissions.
PolarDB for PostgreSQL	Permissions of the target schema owner. Note You can use the Database Owner specified during database creation.

To create a database account and grant permissions to the account:

For self-managed PostgreSQL databases, see the CREATE USER and GRANT syntax.
For a PolarDB for PostgreSQL cluster, see Create a database account and Manage databases.

Preparations

Note

For more information about how to make preparations if your source database is an Amazon RDS for PostgreSQL instance, see the Before you begin section of the "Migrate incremental data from an Amazon RDS for PostgreSQL instance to an ApsaraDB RDS for PostgreSQL instance" topic. For more information about how to make preparations if your source database is an Amazon Aurora PostgreSQL instance, see the Preparation 1: Edit the inbound rule of the Amazon Aurora PostgreSQL instance section of the "Migrate full data from an Amazon Aurora PostgreSQL instance to an ApsaraDB RDS for PostgreSQL instance" topic.
In this example, a self-managed PostgreSQL database that runs on a Linux server is used.

If the version of the self-managed PostgreSQL database is 10.1 or later, you must perform the following operations before you configure a data migration task.

Log on to the server on which the self-managed PostgreSQL database resides.

Modify the postgresql.conf configuration file. Set the wal_level parameter to logical, and make sure that the values of the max_wal_senders and max_replication_slots parameters are greater than the sum of the number of used replication slots in the self-managed PostgreSQL database and the number of DTS instances whose source database is the self-managed PostgreSQL database.

# - 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 make the parameter settings take effect.

Add the CIDR blocks of DTS servers to the pg_hba.conf configuration file of the self-managed PostgreSQL database. Add only the CIDR blocks of the DTS servers that reside in the same region as the destination database. For more information, see Add DTS server IP addresses to a whitelist.
Note
- After you modify the configuration file, execute the SELECT pg_reload_conf(); statement or restart the self-managed PostgreSQL database to make the parameter settings take effect.
- For more information about the pg_hba.conf configuration file, see The pg_hba.conf File. Skip this step if you have set the IP address in the pg_hba.conf file to 0.0.0.0/0. The following figure shows the configurations.
Create the corresponding database and schema in the destination cluster based on the information of the database and schema of the object to be migrated.

If the version of the self-managed PostgreSQL database is 9.4.8 to 10.0, you must perform the following operations before you configure a data migration task:

Download the PostgreSQL source code from the official website, compile the source code, and install PostgreSQL.
1. Download the source code from the PostgreSQL official website based on the version of the self-managed PostgreSQL database.
2. Run the sudo ./configure, sudo make, and sudo make install commands in sequence to configure and compile the source code, and install PostgreSQL.
  Important
  When you compile and install PostgreSQL, the OS version of PostgreSQL must be consistent with the version of the GNU compiler collection (GCC).
  If an error occurs when you run the sudo ./configure command, you can modify the command based on the error message. For example, if the error message is readline library not found. Use --without-readline to disable readline support., you can modify the command to sudo ./configure --without-readline.
  If you use another method to install PostgreSQL, you must compile the ali_decoding plug-in in a test environment that has the same operating system version and GCC version.

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

Download ali_decoding.
Copy the ali_decoding directory to the contrib directory of PostgreSQL that is compiled and installed.

Go to the ali_decoding directory and replace the content of the Makefile file with the following script:

# 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)

# Run the following commands to install the ali_decoding plug-in:
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

Go to the ali_decoding directory, and run the sudo make and sudo make install commands in sequence to compile the ali_decoding plug-in and obtain the files that are required to install the ali_decoding plug-in.
Copy the files to the specified directories.

Create the corresponding database and schema in the destination cluster based on the information of the database and schema of the object to be migrated.

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 select the source and destination instances, we recommend that you carefully read the Limits at the top of the page. This helps ensure that you can successfully create and run the data migration task.

Category	Configuration	Note
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 PostgreSQL.
	Access Method	Select an option based on the deployment location of the source database. This example describes the configuration process for a Self-managed Database on ECS. Note If you select another method to access the self-managed database, you must perform the required preparations. For more information, see Preparations.
	Instance Region	The region in which the self-managed PostgreSQL database resides.
	ECS Instance ID	Enter the ID of the ECS instance for the self-managed PostgreSQL database.
	Port Number	Enter the service port for the self-managed PostgreSQL database. The default is 5432.
	Database Name	Enter the name of the database that contains the objects to migrate.
	Database Account	Enter the database account for the self-managed PostgreSQL database. For permission requirements, see Permissions required for database accounts.
	Database Password	The password that is used to access the database instance.
	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	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	Select PolarDB for PostgreSQL.
	Access Method	Select Alibaba Cloud Instance.
	Instance Region	The region where the destination PolarDB for PostgreSQL cluster resides.
	Instance ID	Select the ID of the destination PolarDB for PostgreSQL cluster.
	Database Name	Enter the name of the database in the destination PolarDB for PostgreSQL cluster that will contain the migration objects.
	Database Account	Enter the database account for the destination PolarDB for PostgreSQL cluster. For permission requirements, see Permission requirements for database accounts.
	Database Password	The password that is used to access the database instance.

Click Test Connectivity and Proceed in the lower part of the page.
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 DTS server IP addresses to a whitelist.
- If the source or destination database is a self-managed database and its Access Method is not set to Alibaba Cloud Instance, click Test Connectivity in the CIDR Blocks of DTS Servers dialog box.

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

Configuration	Note
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.
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 Map object names. Ignore Errors and Proceed: skips the precheck for identical table names in the source and destination databases. Warning If you select Ignore Errors and Proceed, data inconsistency may occur and your business may be exposed to 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.
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 schemas or tables as the objects to be migrated. If you select tables as the objects to be migrated, DTS does not migrate other objects, such as views, triggers, and stored procedures, to the destination database. If a table to be migrated contains SERIAL data type, and you select Migration Types as Schema Migration, we recommend that you also select Sequence or entire schema migration.
Selected Objects	To rename an object that you want to migrate to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object. To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time. Note If you use the object name mapping feature to rename an object, other objects that depend on the object may fail to be migrated. To set WHERE conditions to filter data, right-click the table to be migrated in the Selected Objects section. In the dialog box that appears, set the filter conditions. For more information, see Set filter conditions. To select SQL operations to migrate at the database or table level, right-click the object to be migrated in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to migrate.

Click Next: Advanced Settings to configure advanced settings.

Configuration	Note
Dedicated Cluster for Task Scheduling	By default, DTS schedules the data migration task to the shared cluster if you do not specify a dedicated cluster. If you want to improve the stability of data migration tasks, purchase a dedicated cluster. 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	Select an environment tag to identify the instance as needed. This is not required for this example.
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.

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 the 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.

Prerequisites

Precautions

Billing

Migration types

Supported objects to be migrated

SQL operations that support incremental migration

Permissions required for database accounts

Preparations

Procedure

DTS console

DMS console