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 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.

Limits

Type Description
Limits on the source database
  • Requirements for the objects to be synchronized:
    • The source database 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.
  • The following requirements for data logs must be met:
    • The data logging feature must be enabled.
    • Data logs are retained for at least 7 days during initial full data synchronization. You can wait until initial full data synchronization is complete, and then clear the data logs generated in the source database after the DTS task is run.
      Note To ensure data security, the DTS server stores only 50 GB of data logs or the data logs for the last 24 hours. If the limit is exceeded, the DTS server automatically clears the cached logs.
      Warning If you clear the data logs of the source database during initial full data synchronization, the data synchronization task may fail. For example, initial full data synchronization takes more than 24 hours due to the large data volume in the source database and abnormal writing in the destination database. In this case, if the data logs of the source database are cleared during initial full data synchronization, DTS cannot obtain the data logs generated 24 hours ago. Therefore, the data synchronization task may fail.
  • 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 partition 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 of 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.
  • We recommend that you do not use gh-ost or pt-online-schema-change to perform data definition language (DDL) operations on source tables during data synchronization. Otherwise, data synchronization may fail.
  • To ensure that the latency of data synchronization is accurate, DTS adds a heartbeat table to the source database. The name of the heartbeat table is dts_log_heart_beat.
  • 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 data manipulation language (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.

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, see Synchronization topologies.

SQL operations that can be synchronized

Operation type SQL statements
DML INSERT, UPDATE, and DELETE
DDL ADD COLUMN

Permissions required for database accounts

Database Required permissions References
Self-managed Oracle database The database administrator (DBA) permission CREATE USER and GRANT
Note If you need to synchronize incremental data from an Oracle database but the DBA permission cannot be granted to the database account, you can grant fine-grained permissions to the account. For more information, see Grant fine-grained permissions to an Oracle database account.
AnalyticDB for PostgreSQL instance The 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.

Grant fine-grained permissions to an Oracle database account

If you need to synchronize incremental data from an Oracle database but the DBA permission cannot be granted to the database account, you can grant fine-grained permissions to the account. The following sample statements show you how to grant specific permissions to an Oracle database account.
  • Enable supplemental logging at the database or table level
    Supplemental logging level Procedure
    Database-level supplemental logging
    1. Check whether minimal supplemental logging is enabled:
      SELECT supplemental_log_data_min, supplemental_log_data_pk, supplemental_log_data_ui FROM v$database;
    2. Enable minimal supplemental logging:
      alter database add supplemental log data;
    3. Enable primary key and unique key supplemental logging at the database level:
      alter database add supplemental log data (primary key,unique index) columns;
    Table-level supplemental logging
    1. Enable minimal supplemental logging:
      alter database add supplemental log data;
    2. Enable table-level supplemental logging by using one of the following methods:
      • Enable table-level supplemental logging for all columns:
        alter table tb_name add supplemental log data (all) columns;
      • Enable primary key supplemental logging at the table level:
        alter table table_name add supplemental log data (primary key) columns;
  • Grant fine-grained permissions to an Oracle database account
create session;
connect;
resource;
execute on sys.dbms_logmnr;
select on v_$logmnr_contents;
select on v_$log;
select on v_$logfile;
select on v_$archived_log;
select on v_$logmnr_logs;
select on v_$parameter;
select on v_$database;
select on all_objects;
select on all_tab_cols;
select on dba_registry;
select any table;
select any transaction;
select on v_$active_instances;
select on v_$instance;
select on sys.USER$;
select on SYS.OBJ$;
select on SYS.COL$;
select on SYS.IND$;
select on SYS.ICOL$;
select on SYS.CDEF$;
select on SYS.CCOL$;
select on SYS.TABPART$;
select on SYS.TABSUBPART$;
select on SYS.TABCOMPART$;
select on gv_$listener_network;
# Grant permissions on the pluggable database (PDB) and container database (CDB).
# Grant permissions on the PDB:
create   session;
connect;
resource;
select on  all_objects;
select on  all_tab_cols;
select on  dba_registry;
select any table;
select any transaction;
select on v_$log;
select on v_$logfile;
select on v_$archived_log;
select on v_$parameter;
select on v_$database;
select on v_$active_instances;
select on v_$instance;
select on V_$PDBS;
select on sys.USER$;
select on SYS.OBJ$;
select on SYS.COL$;
select on SYS.IND$;
select on SYS.ICOL$;
select on SYS.CDEF$;
select on SYS.CCOL$;
select on SYS.TABPART$;
select on SYS.TABSUBPART$;
select on SYS.TABCOMPART$;

# Grant permissions on the CDB:
create   session;
LOGMINING;
select on v_$logmnr_contents;

# The following sample statements show you how to grant permissions to a database account named rdsdt_dtsacct.
create user rdsdt_dtsacct IDENTIFIED BY DTStest1234;
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_$logmnr_contents to rdsdt_dtsacct;
grant select on sys.USER$ 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;
# The following sample statements show you how to grant permissions on the PDB and CDB to a database account named dtstest.
# Grant permissions on the PDB:
create user rdsdt_dtsacct IDENTIFIED BY DTStest1234;
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 permissions on the CDB by using one of the following methods:
# Create a database account named C## rdsdt_dtsacct.
create user C##rdsdt_dtsacct IDENTIFIED BY DTStest1234;
grant create session to C##rdsdt_dtsacct;
grant connect to C##rdsdt_dtsacct;
grant resource to C##rdsdt_dtsacct;
grant select on v_$logmnr_contents to rdsdt_dtsacct;
grant LOGMINING to C##rdsdt_dtsacct;
grant EXECUTE_CATALOG_ROLE to C##rdsdt_dtsacct;
grant execute on sys.dbms_logmnr to C##rdsdt_dtsacct;
# Create a database account named rdsdt_dtsacct.
alter session set "_ORACLE_SCRIPT"=true;
create user rdsdt_dtsacct IDENTIFIED BY DTStest1234;
grant create session to rdsdt_dtsacct;
grant connect to rdsdt_dtsacct;
grant select on v_$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;

Procedure

  1. Log on to the .
    Note You can also log on to the Data Management (DMS) console. In the top navigation bar, choose DTS > Data Synchronization.
  2. In the upper-left corner of the page, select the region where the data synchronization instance resides.
    Select a region
  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 an informative name to identify the task. You do not need to use a unique task name.

    Source Database Database Type Select Oracle.
    Access Method Select an instance type based on the deployment of the source database. In this example, select Self-managed Database on ECS.
    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 Select the region where the self-managed Oracle database resides.
    ECS Instance ID Select the ID of the ECS instance that hosts the self-managed Oracle database.
    Port Number Enter the service port number of the self-managed Oracle database. The default port number is 1521.
    Oracle Type
    • 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, select Non-RAC Instance.
    Database Account Enter the account of the self-managed Oracle database. For information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password

    Enter the password of the database account.

    Destination Database Database Type Select AnalyticDB for PostgreSQL.
    Access Method Select Alibaba Cloud Instance.
    Instance Region Select the region where the destination AnalyticDB for PostgreSQL instance resides.
    Instance ID Select the ID of the destination AnalyticDB for PostgreSQL instance.
    Database Name Enter the name of the destination database in the AnalyticDB for PostgreSQL instance.
    Database Account Enter the database account of the destination AnalyticDB for PostgreSQL instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password

    Enter the password of the database account.

  4. In the lower part of the page, click Test Connectivity and Proceed.
  5. Select objects for the task and configure advanced settings.
    • Basic SettingsBasic Settings
      Parameter Description
      Task Stages

      Incremental Data Synchronization is selected by default. You must also select Schema Synchronization and Full Data Synchronization. After the precheck, DTS synchronizes the historical data of the selected objects from the source instance to the destination cluster. 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 identical table names, the precheck is passed. Otherwise, an error is returned during 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 identical table 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 consistency is not guaranteed and your business may be exposed to potential risks.
        • If the source and destination databases have the same schema, DTS does not synchronize data records that have the same primary keys as data records in the destination database.
        • If the source and destination databases have different schemas, data may fail to be initialized. In this case, only some columns are synchronized or the data synchronization task fails.
      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 and 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.
        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: <Data synchronization instance ID>:<Source database name>.<Source schema name>.<Source 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 of 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 is selected by default.
      DDL and DML Operations to Be Synchronized Select the DDL and DML operations that you want to synchronize. For more information, see SQL operations that can be synchronized.
      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 move the objects to the Selected Objects section.

      Note You can select columns, tables, or databases as the objects to be synchronized.
      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 DDL and DML operations that you want to synchronize. For more information, see SQL operations that can be synchronized.
    • Advanced SettingsAdvanced Settings
      Parameter Description
      Set Alerts
      Specify whether to set alerts for the data synchronization task. If the task fails or the synchronization latency exceeds the threshold, the alert contacts will receive notifications.
      • Select No if you do not want to set alerts.
      • Select Yes to set alerts. In this case, you must also set the alert threshold and alert contacts.
      Retry Time for Failed Connections
      Specify the retry time for failed connections. Valid values: 10 to 1440. Unit: minutes. Default value: 120. We recommend that you set the retry time to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails.
      Note
      • If multiple DTS instances have the same source or destination database, the lowest value takes effect. For example, the retry time is set to 30 minutes for Instance A and 60 minutes for Instance B, DTS retries failed connections at an interval of 30 minutes.
      • When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
      Enclose Object Names in Quotation Marks
      Specify whether you need to enclose object names in quotation marks. If you select Yes and the following conditions are met, DTS encloses object names in single or double quotation marks during schema synchronization and incremental data synchronization.
      • The business environment of the source database is case-sensitive but the database name contains 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 DTS synchronizes data to the destination database, 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 column and distribution column of the tables that you want to synchronize to the destination AnalyticDB for PostgreSQL instance.
    AnalyticDB for PostgreSQL: Specify the primary key column and distribution key
  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, you can click the Info icon icon next to each failed item to view details.
      • You can troubleshoot the issues based on the causes and run a precheck again.
      • If you do not need to troubleshoot the issues, you can ignore failed items and run a precheck again.
  8. Wait until the Success Rate becomes 100%. Then, click Next: Purchase Instance.
  9. On the Purchase Instance page, specify the Billing Method and Instance Class parameters for the data synchronization instance. The following table describes the parameters.
    Section Parameter Description
    Parameters Billing Method
    • Subscription: You can pay for your subscription when you create an instance. We recommend that you select the subscription billing method for long-term use because it is more cost-effective than the pay-as-you-go billing method. You can save more costs with longer subscription periods.
    • Pay-as-you-go: A pay-as-you-go instance is billed on an hourly basis. We recommend that you select the pay-as-you-go billing method for short-term use. If you no longer require your pay-as-you-go instance, you can release it to reduce costs.
    Instance Class DTS 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 channels.
    Subscription Length If you select the subscription billing method, set the subscription length and the number of instances that you want to create. The subscription length can be one to nine months or one to three years.
    Note This parameter is available only if you select the subscription billing method.
  10. Read and select 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.