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Migrate self-managed PostgreSQL to PolarDB for PostgreSQL (Oracle compatible)

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

Prerequisites

Usage notes

Note

  • During schema and table structure migration, DTS migrates foreign keys from the source database to the target database.

  • During full migration and incremental migration, DTS temporarily disables constraint checks and foreign key cascading operations at the session level. If cascading update or delete operations occur on the source database while the task is running, data inconsistency may occur.

Type

Description

Source database limits

  • Bandwidth requirement: 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 primary keys or UNIQUE constraints, and the values in the key columns must be unique. Otherwise, data may be duplicated in the destination database.

    Note

    If the destination tables are not created by DTS (you did not select Schema Migration for Migration Types), make sure that the destination tables have the same primary keys or non-empty UNIQUE constraints as the source tables. Otherwise, data may be duplicated in the destination database.

    The names of the databases to be migrated cannot contain hyphens (-), such as dts-testdata.

  • If you migrate data at the table level and need to edit the migration objects, such as mapping table or column names, a single data migration task can migrate a maximum of 1,000 tables. If you exceed this limit, an 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 logs (WALs):

    • The wal_level parameter must be set to logical.

    • For an incremental migration task, DTS requires that WALs in the source database are retained for more than 24 hours. For a task that includes both full migration and incremental migration, DTS requires that WALs are retained for at least 7 days. You can change the log retention period to more than 24 hours after the full migration is complete. If the task fails because DTS cannot obtain the required WALs, or in extreme cases, data inconsistency or data loss occurs, the issue is not covered by the DTS Service-Level Agreement (SLA) because the log retention period is shorter than required.

  • Source database operation limits:

    • If a failover occurs on the self-managed PostgreSQL database, the migration fails.

    • Due to the limits of logical replication in the source database, if a single piece of data to be migrated exceeds 256 MB after an incremental change, the migration instance may fail and cannot be recovered. You must reconfigure the migration instance.

    • During full migration, do not perform DDL operations to change the schema of the database or tables. Otherwise, the data migration task fails.

    • If you perform only full data migration, do not write new data to the source database. Otherwise, the data in the source and destination databases will be inconsistent. To ensure real-time data consistency, select Full Data Migration and Incremental Data Migration.

  • If the source database has long-running transactions and the instance performs incremental migration, the write-ahead logs (WALs) generated before the long-running transactions are committed cannot be cleared. This may cause the WALs to accumulate and exhaust the disk space of the source database.

  • During the migration, if you perform a major engine version upgrade on the source database, the migration instance fails and cannot be recovered. You must reconfigure the migration instance.

Other limits

  • For a full or incremental migration task, if the tables to be migrated in the source database 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 is a privileged account. 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 (when session_replication_role is replica), if cascade update or delete operations occur in the source database, data inconsistency may occur. After the DTS migration task is released, you can change the session_replication_role parameter back to origin.

  • If a table to be migrated contains a SERIAL column, the source database automatically creates a sequence for that column. Therefore, when you configure the Source Objects, if you select Schema Migration for Migration Types, select Sequence or migrate the entire schema. Otherwise, the migration instance may fail.

  • If the migration instance performs incremental data migration, you must run the ALTER TABLE schema.table REPLICA IDENTITY FULL; command on the tables to be migrated in the source database before you write data to them. This ensures data consistency. This requirement applies in the following two scenarios. During the execution of this command, do not perform table lock operations to avoid deadlocks. If you skip the related check in the precheck, DTS automatically runs this command during the instance initialization.

    • 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.

  • Data Transmission Service (DTS) creates the following temporary tables in the source database to obtain the DDL statements of incremental data, the schemas of incremental tables, and heartbeat information. During data migration, do not delete temporary tables in the source database. Otherwise, the data migration 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 migration latency for incremental data, DTS adds a heartbeat table named dts_postgres_heartbeat to the source database.

  • During incremental data migration, DTS creates a replication slot with the dts_sync_ prefix in the source database to replicate data. Using this replication slot, DTS can obtain incremental logs from the source database within the last 15 minutes. When the data migration fails or the migration instance is released, DTS attempts to automatically clear this replication slot.

    Note

    • If you change the password of the source database account used by the task or delete the DTS IP address whitelist from the source database during data migration, the replication slot cannot be automatically cleared. In this case, you must manually clear the replication slot in the source database to prevent it from accumulating and occupying disk space, which can make the source database unavailable.

    • If a failover occurs in the source database, you must log on to the secondary database to manually clear the slot.

  • A single data migration task can migrate only one database. To migrate multiple databases, configure a separate data migration task for each database.

  • DTS does not support the migration of tables created by the TimescaleDB extension, tables with cross-schema inheritance, or tables with unique indexes based on expressions.

  • Schemas created by installing extensions cannot be migrated. You cannot obtain information about these schemas in the DTS console when you configure the task.

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

  • Full data migration involves concurrent INSERT operations, which can cause table fragmentation in the destination database. As a result, the table storage space in the destination database will be larger than that in the source database after full migration is complete.

  • Confirm whether the migration precision that DTS uses for columns of the FLOAT or DOUBLE data type meets your business requirements. DTS reads the values of these columns using ROUND(COLUMN,PRECISION). If the precision is not explicitly defined, DTS uses a precision of 38 for FLOAT and 308 for DOUBLE.

  • DTS attempts to recover failed migration tasks within seven days. Therefore, before you switch your business to the destination instance, make sure to end or release the task. Alternatively, use the revoke command to revoke the write permissions of the account that DTS uses to access the destination instance. This prevents the source data from overwriting the data in the destination instance if the task is automatically recovered.

  • DTS validates data content but does not support the validation of metadata such as sequences. You must validate the metadata yourself.

  • After you switch your business to the destination instance, new sequences do not start incrementing from the maximum value of the source sequences. You must update the sequence values in the destination database before the switchover. For more information, see Update the sequence values 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 migrating partitioned tables, include both the parent table and its child tables as synchronization objects. Otherwise, data inconsistency may occur for the partitioned table.

    Note

    The parent table of a PostgreSQL partitioned table does not store data directly. All data is stored in the child tables (partitions). The sync task must include the parent table and all its child tables. Otherwise, data in the child tables may not be synchronized, leading to data inconsistency between the source and destination.

Special cases

  • If the source instance is an ApsaraDB RDS for PostgreSQL instance, do not change its connection address or zone during migration. Otherwise, the migration fails.

  • If the source instance is a Google Cloud Platform Cloud SQL for PostgreSQL instance, set Database Account to an account that has the cloudsqlsuperuser permission. When you select migration objects, select objects that this account has permission to manage. Alternatively, grant the Owner permission of the objects to this account. For example, run the GRANT <Owner_of_the_object_to_be_migrated> TO <source_database_account_for_the_task> command to allow this account to perform operations as the owner of the objects.

    Note

    An account with the cloudsqlsuperuser permission cannot manage data owned by other accounts with the cloudsqlsuperuser permission.

  • If the source instance is a self-managed PostgreSQL database, make sure that the values of the max_wal_senders and max_replication_slots parameters are greater than the total number of replication slots in use and the number of DTS instances to be created with this database as the source.

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 schema definitions of the migration objects from the source database to the destination database.

  • Full migration

    DTS migrates all historical data of the specified migration objects from the source database to the destination database.

  • Incremental migration

    After a full migration is complete, DTS migrates incremental data updates from the source database to the destination database. Incremental migration lets you smoothly migrate data without interrupting your self-managed applications.

Supported objects

  • schema and table

    Note

    This includes primary key, unique key, foreign key, DATATYPE (built-in data type), and default constraint.

  • view, procedure (for PostgreSQL 11 or later), function, rule, sequence, extension, trigger, aggregate, index, operator, and domain

Supported SQL operations

Operation type

SQL statement

DML

INSERT, UPDATE, and DELETE

DDL

  • Only data migration tasks created after October 1, 2020 (UTC+8)October 1, 2020 (UTC+8) support DDL operations.

    Important

  • The data migration task supports the following DDL statements. The source database account must be a privileged account:

    • 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 (The source PostgreSQL database must be version 11 or later.)

    • CREATE INDEX ON TABLE

    Important

    • Additional information in DDL statements, such as CASCADE or RESTRICT, is not migrated.

    • If a session uses the SET session_replication_role = replica command, its DDL statements are not migrated.

    • DDL statements executed by calling functions are not migrated.

    • If a single transaction from the source database contains both DML and DDL statements, the DDL statements are not migrated.

    • If a single transaction from the source database contains DDL statements for objects not selected for migration, the DDL statements are not migrated.

    • CREATE SEQUENCE is not currently supported.

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

Database account permissions

Database

Schema migration

Full data migration

Incremental data migration

self-managed PostgreSQL

USAGE permission on pg_catalog

SELECT permission on the source objects

superuser

PolarDB for PostgreSQL (Compatible with Oracle) cluster

database owner permissions

Important

The database owner is specified when you create a database.

To create a database account and grant permissions to it, see the following topics:

Prerequisites

Note

Follow these steps for all versions of self-managed PostgreSQL.

  1. Log in to the server hosting your self-managed PostgreSQL database.

  2. Run the following command to query the number of used replication slots in the database.

    select count(1) from pg_replication_slots;

  3. Modify the postgresql.conf configuration file. Set the wal_level parameter to logical, and ensure that the max_wal_senders and max_replication_slots parameters are greater than the number of used replication slots plus the number of DTS instances that you plan to create.

    # - 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, you must restart the self-managed PostgreSQL database to apply the changes.

  4. Add the CIDR blocks of DTS servers to the pg_hba.conf configuration file of your self-managed PostgreSQL database. You only need to add the CIDR blocks for the DTS servers in the region where your destination database is located. For more information, see Add the CIDR blocks of DTS servers to a whitelist.

    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 settings in this 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 figure), you can skip this step.

    IP

  5. In the destination database instance, create databases and schemas that correspond to the source objects you are migrating.

For self-managed PostgreSQL versions 9.4.8 to 10.0, follow these additional steps.

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

    1. Download the source code for your self-managed PostgreSQL version from the PostgreSQL official website.

    2. 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 must be compatible with the GNU Compiler Collection (GCC) version.

      • 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., change the command to sudo ./configure --without-readline.

      • If you install PostgreSQL by using another method, you must compile the ali_decoding plugin in a test environment that uses the same operating system and GCC versions as your production environment.

  2. Download, compile, and install the ali_decoding plugin provided by DTS.

    1. Download ali_decoding.

    2. Copy the entire ali_decoding directory to the contrib directory of your PostgreSQL installation.

      contrib目录

    3. Go to the ali_decoding directory and replace the contents of the Makefile file with the following code:

      # 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 code 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. Run the sudo make and sudo make install commands in sequence to compile the ali_decoding plugin and generate the required installation files.

    5. Copy the following files to the specified locations.

      指定位置

  3. In the destination database instance, create databases and schemas that correspond to the source objects you are migrating.

Procedure

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

    From the DTS console

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

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

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

    From the DMS console

    Note

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

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

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

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

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

  3. Configure the source and destination databases.

    Warning

    After you select the source and destination instances, read the Limits at the top of the page to ensure that the migration task can be created and run successfully.

    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

    Database Type

    Select PostgreSQL.

    Connection Type

    Select Self-managed Database Connected via Express Connect/VPN Gateway/Smart Access Gateway.

    Note

    Selecting a self-managed database requires some preparation. For more information, see Preparations.

    Instance Region

    Select the region of the self-managed PostgreSQL database.

    Cross-account

    In this example, data is migrated within the same Alibaba Cloud account. Select No.

    The VPC that has been connected to the source database

    Select the ID of the VPC to which the self-managed PostgreSQL database belongs.

    IP address

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

    Port

    Enter the service port number of the self-managed PostgreSQL database. The default value is 5432.

    Database Name

    Enter the name of the source database that contains the objects to migrate.

    Database Account

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

    Database Password

    Enter the password for the database account.

    Encryption

    Select a connection method. In this example, Non-encrypted is selected.

    If you need to connect to the database by using SSL encryption, select SSL-encrypted, and then upload the CA Certificate, Client Certificate, and Private Key of Client Certificate as needed. Then, enter the Private Key Password of Client Certificate.

    Note

    • If you select SSL-encrypted for a self-managed PostgreSQL database, you must upload the CA Certificate.

    • If you need to use a client certificate, you must upload both the Client Certificate and the Private Key of Client Certificate, and then enter the Private Key Password of Client Certificate.

    • For information about the SSL encryption feature for an RDS for PostgreSQL instance, see SSL connection encryption.

    Destination Database

    Database Type

    Select PolarDB (Compatible with Oracle).

    Connection Type

    Select Self-managed Database Connected via Express Connect/VPN Gateway/Smart Access Gateway.

    Instance Region

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

    Connected VPC

    Select the ID of the VPC to which the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster belongs. You can find the VPC ID on the Basic Information page of the 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 to obtain the IP address for the direct connection endpoint of the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster.

    Port

    Enter the service port number of the destination database. The default value is 1521.

    Database Name

    Enter the name of the database that will contain the migration objects in the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster.

    Database Account

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

    Database Password

    Enter the password for the database account.

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

    Note

    • Ensure that the IP address segment of the DTS service is 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 (the Access Method is not Alibaba Cloud Instance), you must also click Test Connectivity in the CIDR Blocks of DTS Servers dialog box that appears.

  5. Configure the task objects.

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

      Parameter

      Description

      Migration Types

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

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

      Note

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

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

      Processing Mode of Conflicting Tables

      • Precheck and Report Errors: Checks whether tables with the same names exist in the destination database. If no tables with the same names exist, the precheck is passed. If tables with the same names exist, an error is reported during the precheck, and the data migration task does not start.

        Note

        If a table in the destination database has the same name but cannot be easily deleted or renamed, you can change the name of the table in the destination database. For more information, see Object name mapping.

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

        Warning

        Selecting Ignore Errors and Proceed may cause data inconsistency and business risks. For example:

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

          • During full migration, DTS keeps the record in the destination database. The record from the source database is not migrated.

          • During incremental migration, DTS does not keep the record in the destination database. The record from the source database overwrites the record in the destination database.

        • If the table schemas are inconsistent, only some columns of data may be migrated, or the migration may fail. Proceed with caution.

      Source Objects

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

      Note

      • You can select objects at the schema or table level. If you select tables, other objects such as views, triggers, and stored procedures are not migrated.

      • If a table to be migrated contains columns of the SERIAL type and you have selected Migration Types for Schema Migration, also select Sequence or migrate the entire schema.

      Selected Objects
      Note

      • If you use the object name mapping feature to rename an object, other objects that depend on the renamed object may fail to be migrated.

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

      • To select the SQL operations to migrate at the database or table level, right-click an object in the Selected Objects box and select the desired SQL operations in the dialog box that appears.

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

      Parameter

      Description

      Dedicated Cluster for Task Scheduling

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

      Retry Time for Failed Connections

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

      Note

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

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

      Retry Time for Other Issues

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

      Important

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

      Enable Throttling for Full Data Migration

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

      Note

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

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

      Enable Throttling for Incremental Data Migration

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

      Note

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

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

      Environment Tag

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

      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

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

      • No: Does not set an alert.

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

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

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

  6. Save the task and run a precheck.

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

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

    Note

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

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

    • If a warning is reported during the precheck:

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

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

  7. Purchase the instance.

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

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

      Category

      Parameter

      Description

      New Instance Class

      Resource Group Settings

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

      Instance Class

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

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

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

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

      Note

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

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

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