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    AnalyticDB:Synchronize data from a self-managed Oracle database to an AnalyticDB for PostgreSQL instance

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    AnalyticDB:Synchronize data from a self-managed Oracle database to an AnalyticDB for PostgreSQL instance

    Last Updated:Jun 12, 2023

    This topic describes how to synchronize data from a self-managed Oracle database to an AnalyticDB for PostgreSQL instance by using Data Transmission Service (DTS).

    Prerequisites

    • The engine version of the self-managed Oracle database is 9i, 10g, 11g, 12c, 18c, or 19c.

    • The self-managed Oracle database is running in ARCHIVELOG mode. Archived log files are accessible, and a suitable retention period is set for archived log files. For more information, see Managing Archived Redo Log Files.

    • Supplemental logging, including SUPPLEMENTAL_LOG_DATA_PK and SUPPLEMENTAL_LOG_DATA_UI, is enabled for the self-managed Oracle database. For more information, see Supplemental Logging.

    • The destination AnalyticDB for PostgreSQL instance is created. For more information, see Create an instance.

    Usage notes

    Note
    • During schema synchronization, DTS synchronizes foreign keys from the source database to the destination database.
    • During full synchronization and incremental synchronization, DTS temporarily disables checking of foreign key constraints and foreign key cascade operations at the session level. If you perform the cascade update and delete operations on the source database during data synchronization, data inconsistency may occur.
    CategoryDescription
    Limits on the source database
    • Requirements for the objects to be synchronized:
      • The tables to be synchronized must have PRIMARY KEY or UNIQUE constraints, and all fields must be unique. Otherwise, the destination database may contain duplicate data records.
      • If the version of your Oracle database is 12c or later, the names of the tables to be synchronized cannot exceed 30 bytes in length.
      • If you select tables as the objects to be synchronized and you want to edit the tables (such as renaming tables or columns) in the destination database, up to 1,000 tables can be synchronized in a single data synchronization task. If you run a task to synchronize more than 1,000 tables, a request error occurs. In this case, we recommend that you configure multiple tasks to synchronize the tables in batches or configure a task to synchronize the entire database.
    • If the source database is an Oracle Real Application Cluster (RAC) database connected over Express Connect, you must specify a virtual IP address (VIP) for the database when you configure the data synchronization task.
    • If the self-managed Oracle database is an Oracle RAC database, you can only use a VIP rather than a Single Client Access Name (SCAN) IP address when you configure the data synchronization task. After you specify the VIP, node failover of the Oracle RAC database is not supported.
    • The redo logging and archive logging features must be enabled.
      Note

      If you perform only incremental data synchronization, the redo logs and archive logs of the source database must be stored for more than 24 hours. If you perform both full data and incremental data synchronization, the redo logs and archive logs of the source database must be stored for at least seven days. Otherwise, DTS may fail to obtain the redo logs and archive logs and the task may fail. In exceptional circumstances, data inconsistency or loss may occur. After the full data synchronization is complete, you can set the retention period to more than 24 hours. Make sure that you set the retention period of redo logs and archive logs in accordance with the preceding requirements. Otherwise, the service reliability and performance stated in the Service Level Agreement (SLA) of DTS may not be guaranteed.

    • If you perform a primary/secondary switchover on the source database when the data synchronization task is running, the task fails.
    Other limits
    • DTS supports initial schema synchronization for the following types of objects: table, index, constraint, function, sequence, and view.
      Warning
      • Oracle and AnalyticDB for PostgreSQL are heterogeneous databases. DTS does not ensure that the schemas of the source and destination databases are consistent after initial schema synchronization. We recommend that you evaluate the impact of data type conversion on your business. For more information, see Data type mappings for schema synchronization.
      • In this scenario, DTS is incompatible with triggers. We recommend that you delete the triggers of the source database to prevent data inconsistency caused by triggers. For more information, see Configure a data synchronization task for a source database that contains a trigger.
      • For partitioned tables, DTS discards the partition definitions. You must define partitions in the destination database.
    • Before you synchronize data, evaluate the impact of data synchronization on the performance of the source and destination databases. We recommend that you synchronize data during off-peak hours. During initial full data synchronization, DTS uses read and write resources of the source and destination databases. This may increase the loads on the database servers.
    • During initial full data synchronization, concurrent INSERT operations cause fragmentation in the tables of the destination database. After initial full data synchronization is complete, the tablespace of the destination database is larger than that of the source database.
    • DTS calculates synchronization latency based on the timestamp of the latest synchronized data in the destination database and the current timestamp in the source database. If no DML operation is performed on the source database for a long time, the synchronization latency may be inaccurate. If the latency of the synchronization task is too high, you can perform a DML operation on the source database to update the latency.
      Note If you select an entire database as the object to be synchronized, you can create a heartbeat table. The heartbeat table is updated or receives data every second.
    • During data synchronization, we recommend that you use only DTS to write data to the destination database. This prevents data inconsistency between the source and destination databases. For example, if you use tools other than DTS to write data to the destination database, data loss may occur in the destination database when you use Data Management (DMS) to perform online DDL operations.

    Billing

    Synchronization typeTask configuration fee
    Schema synchronization and full data synchronizationFree of charge.
    Incremental data synchronizationCharged. For more information, see Billing overview.

    Supported synchronization topologies

    • One-way one-to-one synchronization

    • One-way one-to-many synchronization

    • One-way many-to-one synchronization

    • One-way cascade synchronization

    For more information about the synchronization topologies supported by DTS, see Synchronization topologies.

    SQL operations that can be synchronized

    Operation type

    SQL statement

    DML

    INSERT, UPDATE, and DELETE

    DDL

    ADD COLUMN

    Permissions required for database accounts

    Database

    Required permission

    References

    Self-managed Oracle database

    DBA

    CREATE USER and GRANT

    AnalyticDB for PostgreSQL instance

    Write permissions on the destination database

    The initial account of the destination AnalyticDB for PostgreSQL instance has the required permissions. For more information, see Create a database account.

    Note

    You can also enter an account that has the RDS_SUPERUSER permission. For more information, see Manage users and permissions.

    Important If you need to synchronize data from an Oracle database but the database administrator (DBA) permission cannot be granted to the database account, you can enable archive logging and supplemental logging, and grant fine-grained permissions to the account.

    1. Enable archive logging and supplemental logging.

      Log typeProcedure
      Archive loggingExecute the following statements to enable archive logging:
      shutdown immediate;
startup mount;
alter database archivelog;
alter database open;
archive log list;
      Supplemental loggingEnable supplemental logging at the database or table level based on your business requirements.
      Note You can enable database-level supplemental logging to ensure the stability of Data Transmission Service (DTS) tasks. You can enable table-level supplemental logging to reduce the disk usage of the source Oracle database.
      • Enable database-level supplemental logging
        1. Execute the following statement to enable minimal supplemental logging:
          alter database add supplemental log data;
        2. Execute the following statement to enable primary key and unique key supplemental logging at the database level:
          alter database add supplemental log data (primary key,unique index) columns;
      • Enable table-level supplemental logging
        1. Execute the following statement to enable minimal supplemental logging:
          alter database add supplemental log data;
        2. Enable table-level supplemental logging by using one of the following methods:
          • Execute the following statement to enable primary key supplemental logging at the table level:
            alter table table_name add supplemental log data (primary key) columns;
          • Execute the following statement to enable table-level supplemental logging for all columns:
            alter table tb_name add supplemental log data (all) columns ;

    2. Grant fine-grained permissions to an Oracle database account.

      Oracle versions 9i to 11g

      # Create a database account named rdsdt_dtsacct and grant permissions to the account.
create user rdsdt_dtsacct IDENTIFIED BY rdsdt_dtsacct;
grant create session to rdsdt_dtsacct;
grant connect to rdsdt_dtsacct;
grant resource to rdsdt_dtsacct;
grant execute on sys.dbms_logmnr to rdsdt_dtsacct;
grant select on V_$LOGMNR_LOGS to rdsdt_dtsacct;
grant select on  all_objects to rdsdt_dtsacct;
grant select on  all_tab_cols to rdsdt_dtsacct;
grant select on  dba_registry to rdsdt_dtsacct;
grant select any table to rdsdt_dtsacct;
grant select any transaction to rdsdt_dtsacct;
-- v$log privileges
grant select on v_$log to rdsdt_dtsacct;
-- v$logfile privileges
grant select on v_$logfile to rdsdt_dtsacct;
-- v$archived_log privileges
grant select on v_$archived_log to rdsdt_dtsacct;
-- v$parameter privileges
grant select on v_$parameter to rdsdt_dtsacct;
-- v$database privileges
grant select on v_$database to rdsdt_dtsacct;
-- v$active_instances privileges
grant select on v_$active_instances to rdsdt_dtsacct;
-- v$instance privileges
grant select on v_$instance to rdsdt_dtsacct;
-- v$logmnr_contents privileges
grant select on v_$logmnr_contents to rdsdt_dtsacct;
-- system tables
grant select on sys.USER$ to rdsdt_dtsacct;
grant select on SYS.OBJ$ to rdsdt_dtsacct;
grant select on SYS.COL$ to rdsdt_dtsacct;
grant select on SYS.IND$ to rdsdt_dtsacct;
grant select on SYS.ICOL$ to rdsdt_dtsacct;
grant select on SYS.CDEF$ to rdsdt_dtsacct;
grant select on SYS.CCOL$ to rdsdt_dtsacct;
grant select on SYS.TABPART$ to rdsdt_dtsacct;
grant select on SYS.TABSUBPART$ to rdsdt_dtsacct;
grant select on SYS.TABCOMPART$ to rdsdt_dtsacct;
grant select on v$database to rdsdt_dtsacct;
grant select on dba_objects to rdsdt_dtsacct;
grant select on DBA_TAB_COMMENTS to rdsdt_dtsacct;
grant select on dba_tab_cols to rdsdt_dtsacct;

      Oracle versions 12c to 19c that use the multitenant architecture

      # Switch to the pluggable database (PDB). Create a database account named rdsdt_dtsacct and grant permissions to the account.
ALTER SESSION SET container = ORCLPDB1;
create user rdsdt_dtsacct IDENTIFIED BY rdsdt_dtsacct;
grant create  session to rdsdt_dtsacct;
grant connect  to rdsdt_dtsacct;
grant resource to rdsdt_dtsacct;
grant execute on sys.dbms_logmnr to rdsdt_dtsacct;
grant select on  all_objects to rdsdt_dtsacct;
grant select on  all_tab_cols to rdsdt_dtsacct;
grant select on  dba_registry to rdsdt_dtsacct;
grant select any table to rdsdt_dtsacct;
grant select any transaction to rdsdt_dtsacct;
-- v$log privileges
grant select on v_$log to rdsdt_dtsacct;
-- v$logfile privileges
grant select on v_$logfile to rdsdt_dtsacct;
-- v$archived_log privileges
grant select on v_$archived_log to rdsdt_dtsacct;
-- v$parameter privileges
grant select on v_$parameter to rdsdt_dtsacct;
-- v$database privileges
grant select on v_$database to rdsdt_dtsacct;
-- v$active_instances privileges
grant select on v_$active_instances to rdsdt_dtsacct;
-- v$instance privileges
grant select on v_$instance to rdsdt_dtsacct;
-- v$logmnr_contents privileges
grant select on v_$logmnr_contents to rdsdt_dtsacct;
grant select on sys.USER$ to rdsdt_dtsacct;
grant select on SYS.OBJ$ to rdsdt_dtsacct;
grant select on SYS.COL$ to rdsdt_dtsacct;
grant select on SYS.IND$ to rdsdt_dtsacct;
grant select on SYS.ICOL$ to rdsdt_dtsacct;
grant select on SYS.CDEF$ to rdsdt_dtsacct;
grant select on SYS.CCOL$ to rdsdt_dtsacct;
grant select on SYS.TABPART$ to rdsdt_dtsacct;
grant select on SYS.TABSUBPART$ to rdsdt_dtsacct;
grant select on SYS.TABCOMPART$ to rdsdt_dtsacct;
-- V$PDBS privileges
grant select on V_$PDBS to rdsdt_dtsacct;
grant select on v$database to rdsdt_dtsacct;
grant select on dba_objects to rdsdt_dtsacct;
grant select on DBA_TAB_COMMENTS to rdsdt_dtsacct;
grant select on dba_tab_cols to rdsdt_dtsacct;
grant select_catalog_role TO rdsdt_dtsacct;

# Switch to the container database (CDB). Create a database account and grant permissions to the account.
ALTER SESSION SET container = CDB$ROOT;

# Create a database account named rdsdt_dtsacct and grant permissions to the account. You must modify the default parameters of the Oracle database.
alter session set "_ORACLE_SCRIPT"=true;
create user rdsdt_dtsacct IDENTIFIED BY rdsdt_dtsacct;
grant create session to rdsdt_dtsacct;
grant connect to rdsdt_dtsacct;
grant select on v_$logmnr_contents to rdsdt_dtsacct;
grant LOGMINING TO rdsdt_dtsacct;
grant EXECUTE_CATALOG_ROLE to rdsdt_dtsacct;
grant execute on sys.dbms_logmnr to rdsdt_dtsacct;
grant select on v$database to rdsdt_dtsacct;
grant select on dba_objects to rdsdt_dtsacct;
grant select on DBA_TAB_COMMENTS to rdsdt_dtsacct;
grant select on dba_tab_cols to rdsdt_dtsacct;

      Oracle versions 12c to 19c that use a non-multitenant architecture

      # Create a database account named rdsdt_dtsacct and grant permissions to the account.
create user rdsdt_dtsacct IDENTIFIED BY rdsdt_dtsacct;
grant create  session to rdsdt_dtsacct;
grant connect  to rdsdt_dtsacct;
grant resource to rdsdt_dtsacct;
grant select on V_$LOGMNR_LOGS to rdsdt_dtsacct;
grant select on  all_objects to rdsdt_dtsacct;
grant select on  all_tab_cols to rdsdt_dtsacct;
grant select on  dba_registry to rdsdt_dtsacct;
grant select any table to rdsdt_dtsacct;
grant select any transaction to rdsdt_dtsacct;
-- v$log privileges
grant select on v_$log to rdsdt_dtsacct;
-- v$logfile privileges
grant select on v_$logfile to rdsdt_dtsacct;
-- v$archived_log privileges
grant select on v_$archived_log to rdsdt_dtsacct;
-- v$parameter privileges
grant select on v_$parameter to rdsdt_dtsacct;
-- v$database privileges
grant select on v_$database to rdsdt_dtsacct;
-- v$active_instances privileges
grant select on v_$active_instances to rdsdt_dtsacct;
-- v$instance privileges
grant select on v_$instance to rdsdt_dtsacct;
-- v$logmnr_contents privileges
grant select on v_$logmnr_contents to rdsdt_dtsacct;
grant select on sys.USER$ to rdsdt_dtsacct;
grant select on SYS.OBJ$ to rdsdt_dtsacct;
grant select on SYS.COL$ to rdsdt_dtsacct;
grant select on SYS.IND$ to rdsdt_dtsacct;
grant select on SYS.ICOL$ to rdsdt_dtsacct;
grant select on SYS.CDEF$ to rdsdt_dtsacct;
grant select on SYS.CCOL$ to rdsdt_dtsacct;
grant select on SYS.TABPART$ to rdsdt_dtsacct;
grant select on SYS.TABSUBPART$ to rdsdt_dtsacct;
grant select on SYS.TABCOMPART$ to rdsdt_dtsacct;
grant LOGMINING TO rdsdt_dtsacct;
grant EXECUTE_CATALOG_ROLE to rdsdt_dtsacct;
grant execute on sys.dbms_logmnr to rdsdt_dtsacct;
grant select on v$database to rdsdt_dtsacct;
grant select on dba_objects to rdsdt_dtsacct;
grant select on DBA_TAB_COMMENTS to rdsdt_dtsacct;
grant select on dba_tab_cols to rdsdt_dtsacct;

    Procedure

    1. Go to the Data Synchronization page of the new DTS console.
      Note You can also log on to the Data Management (DMS) console. In the top navigation bar, click DTS. In the left-side navigation pane, choose DTS (DTS) > Data Synchronization.
    2. In the upper-left corner of the page, select the region in which the data synchronization instance resides.

    3. Click Create Task. On the page that appears, configure the source and destination databases.

      Section

      Parameter

      Description

      N/A

      Task Name

      DTS automatically generates a task name. We recommend that you specify a name that indicates your business requirements. You do not need to use a unique task name.

      Source Database

      Database Type

      The type of the destination database. Select Oracle.

      Access Method

      The access method of the source database. In this example, Self-managed Database on ECS is selected.

      Note

      If your source database is a self-managed database, you must deploy the network environment for the database. For more information, see Preparation overview.

      Instance Region

      The region where the self-managed Oracle database resides.

      ECS Instance ID

      The ID of the Elastic Compute Service (ECS) instance that hosts the self-managed Oracle database.

      Port Number

      The service port number of the self-managed Oracle database. Default value: 1521.

      Oracle Type

      • The architecture of the source Oracle database. If you select Non-RAC Instance, you must specify the SID parameter.

      • If you select RAC or PDB Instance, you must specify the Service Name parameter.

      In this example, Non-RAC Instance is selected.

      Database Account

      The account of the self-managed Oracle database. For information about the permissions that are required for the account, see the "Permissions required for database accounts" section of this topic.

      Database Password

      The password of the database account.

      Destination Database

      Database Type

      The type of the destination database. Select AnalyticDB for PostgreSQL.

      Access Method

      The access method of the destination database. Select Alibaba Cloud Instance.

      Instance Region

      The region where the destination AnalyticDB for PostgreSQL instance resides.

      Instance ID

      The ID of the destination AnalyticDB for PostgreSQL instance.

      Database Name

      The name of the destination database in the AnalyticDB for PostgreSQL instance.

      Database Account

      The database account of the destination AnalyticDB for PostgreSQL instance. For information about the permissions that are required for the account, see the "Permissions required for database accounts" section of this topic.

      Database Password

      The password of the database account.

    4. In the lower part of the page, click Test Connectivity and Proceed.
      If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must ensure that the ECS instance can access the database. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the whitelist of the database to allow DTS to access the database. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.
      Warning If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the ECS security group rules, security risks may arise. Therefore, before you use DTS to synchronize data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, or connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

    5. Configure objects to synchronize and advanced settings.

      • Basic SettingsBasic Settings (Select SQL Operations)

        Parameter

        Description

        Synchronization Type

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

        Processing Mode of Conflicting Tables

        • Precheck and Report Errors: checks whether the destination database contains tables that have 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 synchronization task cannot be started.

          Note You can use the object name mapping feature to rename the tables that are synchronized to the destination database. You can use this feature if the source and destination databases contain tables that have identical names and the tables in the destination database cannot be deleted or renamed. 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 potential risks.
          • If the source and destination databases have the same schemas, and a data record has the same primary key value as an existing data record in the destination database:
            • During full data synchronization, DTS does not synchronize the data record to the destination database. The existing data record in the destination database is retained.
            • During incremental data synchronization, DTS synchronizes 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, data may fail to be initialized, only some columns are synchronized, or the data synchronization task fails. Operate with caution.

        Merge Tables

        • Yes: In online transaction processing (OLTP) scenarios, sharding is implemented to speed up the response to business tables. In online analytical processing (OLAP) scenarios, you can store a large volume of data in a single table. This makes your SQL queries more efficient. You can merge multiple source tables that have the same schema into a single destination table. This feature allows you to synchronize data from multiple tables in the source database to a single table in the destination database. For more information, see Enable the multi-table merging feature.
          Note
          • After you select multiple tables from the source database, you must change the names of these tables to the name of the destination table. To do this, you can use the object name mapping feature. For more information, see Map object names.
          • DTS adds a column named __dts_data_source to the destination table. This column is used to record the data source. The data type of this column is TEXT. DTS specifies the column values based on the following format: <DTS instance ID>:<Database name>:<Schema name>:<Table name>. Such column values allow DTS to identify each source table. For example, dts********:dtstestdata:testschema:customer1 indicates that the source table is customer1.
          • If you set this parameter to Yes, all the selected source tables in the task are merged into the destination table. If you do not need to merge specific source tables, you can create a separate data synchronization task for these tables.
          Warning We recommend that you do not perform DDL operations to change the schemas of source databases or tables. Otherwise, data inconsistency may occur or the data synchronization task fails.
        • No: This value is selected by default.

        DDL and DML Operations to Be Synchronized

        The DDL and DML operations to synchronize. For more information, see the "SQL operations that can be synchronized" section of this topic.

        Note To select the SQL operations performed on a specific database or table, perform the following steps: In the Selected Objects section, right-click an object. In the dialog box that appears, select the SQL operations that you want to synchronize.

        Select Objects

        Select one or more objects from the Source Objects section and click the Rightwards arrow icon to add the objects to the Selected Objects section.

        Note You can select columns, tables, or databases as the objects to be synchronized. If you select tables or columns as the objects to be synchronized, DTS does not synchronize other objects such as views, triggers, or stored procedures to the destination database.

        Rename Databases and Tables

        • To rename an object that you want to synchronize 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.

        Filter data

        You can specify WHERE conditions to filter data. For more information, see Use SQL conditions to filter data.

        Select the SQL operations to be synchronized

        In the Selected Objects section, right-click an object. In the dialog box that appears, select the DML and DDL operations that you want to synchronize. For more information, see the "SQL operations that can be synchronized" section of this topic.

      • Advanced SettingsAdvanced Settings (Not Replicate Temporary Tables When DMS Performs DDL Operations and Next: Configure Database and Table Fields)

        Parameter

        Description

        Set Alerts

        Specifies whether to configure alerting for the data synchronization task. If the task fails or the synchronization latency exceeds the specified threshold, alert contacts will receive notifications. Valid values:

        Retry Time for Failed Connection

        The retry time range for failed connections. If the source or destination database fails to be connected after the data synchronization task is started, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails.
        Note
        • If you set different retry time ranges for multiple DTS tasks that have the same source or destination database, the shortest retry time range that is set takes precedence.
        • If 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, or release the DTS instance at the earliest opportunity after the source and destination instances are released.

        Enclose Object Names in Quotation Marks

        Specifies whether to enclose object names in quotation marks. If you select Yes and one of the following conditions is met, DTS encloses object names in single quotation marks (') or double quotation marks (") during schema synchronization and incremental data synchronization:
        • The business environment of the source database is case-sensitive but the object names of the database contain both uppercase and lowercase letters.
        • A source table name does not start with a letter and contains characters other than letters, digits, and special characters.
          Note A source table name can contain only the following special characters: underscores (_), number signs (#), and dollar signs ($).
        • The names of the schemas, tables, or columns that you want to synchronize are keywords, reserved keywords, or invalid characters in the destination database.
        Note If you select Yes, after the data synchronization task is complete, you must specify the object name in quotation marks to query the object.
    6. In the lower part of the page, click Next: Configure Database and Table Fields. On the page that appears, set the primary key columns and distribution key columns of the tables that you want to synchronize to the destination AnalyticDB for PostgreSQL instance.
      AnalyticDB for PostgreSQL: Specify the primary key columns and distribution key columns
    7. Click Next: Save Task Settings and Precheck in the lower part of the page.
      Note
      • Before you can start the data synchronization task, DTS performs a precheck. You can start the data synchronization 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 troubleshoot the issues based on the causes, 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 an 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.
    8. Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.
    9. On the Purchase Instance page, configure the Billing Method and Instance Class parameters for the data synchronization instance. The following table describes the parameters.
      SectionParameterDescription
      New Instance ClassBilling Method
      • Subscription: You pay for the instance when you create an instance. The subscription billing method is more cost-effective than the pay-as-you-go billing method for long-term use.
      • Pay-as-you-go: A pay-as-you-go instance is charged on an hourly basis. The pay-as-you-go billing method is suitable for short-term use. If you no longer require a pay-as-you-go instance, you can release the pay-as-you-go instance to reduce costs.
      Instance ClassDTS provides several instance classes that have different performance in synchronization speed. You can select an instance class based on your business scenario. For more information, see Specifications of data synchronization instances.
      Subscription DurationIf you select the subscription billing method, set the subscription duration and the number of instances that you want to create. The subscription duration can be one to nine months or one to three years.
      Note This parameter is displayed only if you select the subscription billing method.
    10. Read and select the check box to agree to the Data Transmission Service (Pay-as-you-go) Service Terms.
    11. Click Buy and Start to start the data synchronization task. You can view the progress of the task in the task list.