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

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

Prerequisites

Usage notes

Note

  • DTS migrates foreign keys during schema migration.

  • During full and incremental data migration, DTS temporarily disables constraint checks and foreign key cascades at the session level. Cascade updates or deletes on the source database while the task runs may cause data inconsistency.

Type

Description

Limits on the source database

  • The server hosting the source database must have sufficient outbound bandwidth; insufficient bandwidth will affect the migration speed.

  • Tables selected for migration must have a primary key or a unique constraint, and the fields in the constraint must be unique. Otherwise, duplicate data may occur in the destination database.

    Note

    If the destination table was not created by Data Transmission Service (DTS) because you did not select Schema Migration as the Migration Types, 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.

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

  • If you select tables as the migration objects and need to edit them (for example, by mapping table or column names), a single migration task can migrate up to 1,000 tables. Exceeding this limit causes an error upon task submission. In this case, split the tables across multiple tasks or configure a task to migrate the entire database.

  • For an incremental data migration, the following write-ahead logging (WAL) requirements apply:

    • The wal_level parameter must be set to logical.

    • For an incremental data migration task, the WAL in the source database must be retained for more than 24 hours. For a task that includes both full and incremental data migration, DTS requires that the WAL be retained for at least 7 days. After the full data migration is complete, you can reduce the retention period to more than 24 hours. If DTS cannot obtain the required WAL, the migration task may fail. In extreme cases, data inconsistency or loss may occur. Issues caused by a WAL retention period shorter than the required duration are not covered by the DTS Service Level Agreement (SLA).

  • Limits on operations in the source database:

    • Performing a primary/secondary switchover on the self-managed PostgreSQL source database will cause the migration to fail.

    • Due to the limitations of logical subscriptions, if a migration instance that includes incremental data migration is running and the size of a single row to be migrated exceeds 256 MB after an incremental change, the migration instance fails irrecoverably, and you must reconfigure it.

    • During the full data migration phase, do not perform DDL operations to change database or table schemas. Otherwise, the data migration task fails.

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

  • If the source database has long-running transactions and the instance is configured for an incremental migration task, the write-ahead logging (WAL) generated before the transactions are committed cannot be cleared. This may cause WAL to accumulate and exhaust the disk space of the source database.

  • If you perform a major version upgrade on the source database while a migration instance is running, the instance fails irrecoverably, and you must reconfigure it.

Other limits

  • This note applies to full or incremental data migration instances for tables that contain foreign keys, triggers, or event triggers. DTS temporarily sets the session_replication_role parameter to replica at the session level during full or incremental migration. If the destination database account does not have this permission, you must manually set the session_replication_role parameter to replica. During this period, if cascade update or delete operations occur in the source database, data inconsistency may result. After the DTS data migration instance is released, you can change the session_replication_role parameter value back to origin.

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

  • For tasks that include 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 for the tables in the following two scenarios. To prevent deadlocks, avoid table-locking operations while this command runs. If you skip the related checks during the precheck, DTS automatically runs this command when it initializes the instance.

    • When the instance runs for the first time.

    • When the migration object granularity is set to Schema and a new table is created in the schema or an existing table is rebuilt by 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.

    • Perform this operation during off-peak hours.

  • DTS creates the following temporary tables in the source database to obtain information such as DDL statements for incremental data, the schemas of incremental tables, and heartbeat data. Do not delete these temporary tables during migration. Otherwise, the DTS task will be disrupted. DTS automatically deletes these tables after the migration 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 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. This replication slot allows DTS to obtain incremental logs from the source database from the last 15 minutes. When a data migration task fails or the migration instance is released, DTS attempts to automatically clean up the replication slot.

    Note

    • If you change the password of the source database account used by the task or remove the DTS IP addresses from the IP address whitelist of the source database during migration, the replication slot cannot be automatically cleaned up. In this case, you must manually clean up the replication slot in the source database to prevent log accumulation, which can exhaust disk space and cause the source database to become unavailable.

    • If a primary/secondary switchover occurs on the source database, you must log on to the secondary database to manually clean up the replication slot.

  • DTS migrates only one database per task. To migrate multiple databases, configure a separate task for each one.

  • DTS does not support migrating TimescaleDB extension tables, tables with cross-schema inheritance, or tables with expression-based unique indexes.

  • Schemas created by plug-ins cannot be migrated and are not available for selection in the console during task configuration.

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

  • Full data migration involves concurrent INSERT operations, which can cause table fragmentation in the destination database, resulting in the destination database consuming more storage space than the source.

  • Confirm whether the migration precision for columns of the FLOAT or DOUBLE data type meets your business requirements. DTS uses the ROUND(COLUMN,PRECISION) function to read values from these columns. If you do not explicitly define a precision, DTS uses a precision of 38 digits for FLOAT and 308 digits for DOUBLE.

  • DTS attempts to resume a failed migration task for up to seven days. Therefore, before you switch your workloads to the destination instance, you must stop or release the task. Alternatively, revoke the write permissions of the account that DTS uses to access the destination instance by using the REVOKE command. This prevents an automatically resumed task from overwriting data in the destination instance.

  • DTS validates data content but not metadata such as sequences; you must validate the metadata yourself.

  • After you switch your workloads to the destination instance, newly written sequences do not increment from the maximum value of the corresponding sequences in the source database. Before you switch your workloads, you must update the sequence values in the destination database. For more information, see Update 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 you migrate a partitioned table, you must include both the parent table and its child partitions as migration 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 its child partitions. A data migration task must include the parent table and all its child partitions. Otherwise, data in the child partitions may be missed, which leads to data inconsistency between the source and destination.

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

Special cases

  • Do not modify the connection endpoint or zone of a source ApsaraDB RDS for PostgreSQL instance during migration, as this will cause the task to fail.

  • If the source instance is Cloud SQL for PostgreSQL, you must specify an account with the cloudsqlsuperuser permission in the Database Account field. When you select the migration objects, select objects that this account is authorized to manage. Alternatively, grant the OWNER role for the objects to this account (for example, run the GRANT <owner_of_the_object_to_be_migrated> TO <source_database_account_used_by_the_task> command).

    Note

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

  • If the source database is a self-managed PostgreSQL instance, ensure the max_wal_senders and max_replication_slots parameter values exceed the sum of existing replication slots and the number of DTS migration instances you plan to create for 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, 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 example), you can skip this step.

    In the pg_hba.conf file, set the addresses for IPv4 connections and replication connections to 0.0.0.0/0 and the authentication method to md5. Sample configuration:

    # "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 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.

      总用量 1008
-rw-r--r--  1 1107 1107    384 9月  27 2016 aclocal.m4
drwxrwxrwx  2 1107 1107   4096 9月  27 2016 config
-rw-r--r--  1 root root 374806 9月   7 10:10 config.log
-rwxr-xr-x  1 root root  39032 9月   7 10:10 config.status
-rwxr-xr-x  1 1107 1107 471157 9月  27 2016 configure
-rw-r--r--  1 1107 1107  75195 9月  27 2016 configure.in
drwxrwxrwx 56 1107 1107   4096 9月   7 10:28 contrib
-rw-r--r--  1 1107 1107   1192 9月  27 2016 COPYRIGHT
drwxrwxrwx  3 1107 1107   4096 9月  27 2016 doc
-rw-r--r--  1 root root   3638 9月   7 10:10 GNUmakefile
-rw-r--r--  1 1107 1107   3638 9月  27 2016 GNUmakefile.in
-rw-r--r--  1 1107 1107    283 9月  27 2016 HISTORY
-rw-r--r--  1 1107 1107  75065 9月  27 2016 INSTALL
-rw-r--r--  1 1107 1107   1489 9月  27 2016 Makefile
-rw-r--r--  1 1107 1107   1209 9月  27 2016 README
drwxrwxrwx 16 1107 1107   4096 9月   7 10:10 src

    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.

      /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 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 the migration task runs 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.

    Access Method

    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

    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

    Database Type

    Select PolarDB (Compatible with Oracle).

    Access Method

    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 VPC ID of the destination PolarDB for PostgreSQL (Compatible with Oracle) cluster. The VPC ID is 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

    Run the ping command to obtain the IP address of 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

      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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