Apsara PolarDB is a next-generation relational database service developed by Alibaba Cloud. It is compatible with MySQL, PostgreSQL, and Oracle database engines. The superior performance of Apsara PolarDB in storage and computing meets diverse requirements of enterprises. This topic describes how to migrate data from a user-created Oracle database to a PolarDB cluster compatible with Oracle by using Data Transmission Service (DTS).

Prerequisites

  • The version of the user-created Oracle database is 9i, 10g, 11g, 12c, 18c, or 19c.
  • The ARCHIVELOG mode is enabled for the user-created Oracle database. 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 user-created Oracle database. For more information, see Supplemental Logging.
  • The tables to be migrated from the user-created Oracle database contain primary keys or UNIQUE NOT NULL indexes.

Precautions

  • DTS uses read and write resources of the source and destination databases during full data migration. This may increase the database load. If the database performance is unfavorable, the specification is low, or the data volume is large, database services may become unavailable. For example, DTS occupies a large amount of read and write resources in the following cases: a large number of slow SQL queries are performed on the source database, the tables have no primary keys, or a deadlock occurs in the destination database. Before you migrate data, evaluate the performance of the source and destination databases. We recommend that you migrate data during off-peak hours. For example, you can migrate data when the CPU usage of the source and destination databases is less than 30%.
  • DTS automatically resumes a failed data migration task. Before you switch your workloads to the destination database, stop or release the data migration task. Otherwise, the data in the source database will overwrite the data in the destination database after the task is resumed.

Billing

Migration type Instance configurations Internet traffic
Schema migration and full data migration Free of charge. Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Pricing.
Incremental data migration Charged. For more information, see Pricing.

Migration types

Migration type Description
Schema migration DTS migrates the schemas of the required objects to the destination database. DTS supports schema migration for the following types of objects: table, view, synonym, trigger, stored procedure, function, package, and user-defined type.
Note However, if an object contains triggers, the data between the source and destination databases will become inconsistent.
Full data migration DTS migrates historical data of the required objects from the user-created Oracle database to the destination PolarDB cluster.
Note During schema migration and full data migration, do not perform DDL operations on the objects to be migrated. Otherwise, the objects may fail to be migrated.
Incremental data migration DTS retrieves redo log files from the user-created Oracle database. Then, DTS synchronizes incremental data from the user-created Oracle database to the destination PolarDB cluster. Incremental data migration allows you to ensure service continuity when you migrate data from the user-created Oracle database to the destination PolarDB cluster.

SQL operations that can be synchronized during incremental data migration

  • INSERT, UPDATE, and DELETE operations
  • CREATE TABLE operations
    Note The CREATE TABLE operations to create partition tables or tables that contain functions cannot be synchronized.
  • ALTER TABLE, DROP TABLE, RENAME TABLE, CREATE INDEX, and ADD INDEX operations

Preparations

Log on to the source Oracle database, create an account for data collection, and grant permissions to the account.

Note If you have created a database account and the account has the permissions that are listed in the following table, skip this step.
Database Schema migration Full data migration Incremental data migration
User-created Oracle database The owner permission on schemas The owner permission on schemas The database administrator (DBA) permission
PolarDB cluster The owner permission on schemas The owner permission on schemas The owner permission on schemas

For more information about how to create and authorize a database account, see the following topics:

Notice If you want to migrate 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.
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 dtstest.
create user dtstest IDENTIFIED BY rdsdt_dtsacct;
grant create session to dtstest;
grant connect to dtstest;
grant resource to dtstest;
grant execute on sys.dbms_logmnr to dtstest;
grant select on v_$logmnr_contents to dtstest;
grant select on v_$log to dtstest;
grant select on v_$logfile to dtstest;
grant select on v_$archived_log to dtstest;
grant select on v_$logmnr_logs to dtstest;
grant select on v_$parameter to dtstest;
grant select on v_$database to dtstest;
grant select on all_objects to dtstest;
grant select on all_tab_cols to dtstest;
grant select on dba_registry to dtstest;
grant select any table to dtstest;
grant select any transaction to dtstest;
grant select on v$active_instances to dtstest;
grant select on v$instance to dtstest;
grant select on sys.USER$ to dtstest;
grant select on SYS.OBJ$ to dtstest;
grant select on SYS.COL$ to dtstest;
grant select on SYS.IND$ to dtstest;
grant select on SYS.ICOL$ to dtstest;
grant select on SYS.CDEF$ to dtstest;
grant select on SYS.CCOL$ to dtstest;
grant select on SYS.TABPART$ to dtstest;
grant select on SYS.TABSUBPART$ to dtstest;
grant select on SYS.TABCOMPART$ to dtstest;
grant select on gv_$listener_network to dtstest;
#The following sample statements show you how to grant permissions on the pluggable database (PDB) and container database (CDB) to a database account named dtstest.
#Grant permissions on the PDB:
create user dtstest IDENTIFIED BY rdsdt_dtsacct;
grant create  session to dtstest;
grant connect  to dtstest;
grant resource to dtstest;
grant select on  all_objects to dtstest;
grant select on  all_tab_cols to dtstest;
grant select on  dba_registry to dtstest;
grant select any table to dtstest;
grant select any transaction to dtstest;
-- v$log privileges
grant select on v_$log to dtstest;
-- v$logfile privileges
grant select on v_$logfile to dtstest;
-- v$archived_log privileges
grant select on v_$archived_log to dtstest;
-- v$parameter privileges
grant select on v_$parameter to dtstest;
-- v$database privileges
grant select on v_$database to dtstest;
-- v$active_instances privileges
grant select on v_$active_instances to dtstest;
-- v$instance privileges
grant select on v_$instance to dtstest;
-- V$PDBS privileges
grant select on V_$PDBS to dtstest;
grant select on sys.USER$ to dtstest;
grant select on SYS.OBJ$ to dtstest;
grant select on SYS.COL$ to dtstest;
grant select on SYS.IND$ to dtstest;
grant select on SYS.ICOL$ to dtstest;
grant select on SYS.CDEF$ to dtstest;
grant select on SYS.CCOL$ to dtstest;
grant select on SYS.TABPART$ to dtstest;
grant select on SYS.TABSUBPART$ to dtstest;
grant select on SYS.TABCOMPART$ to dtstest;

#Grant permissions on the CDB:
create user dtstest IDENTIFIED BY rdsdt_dtsacct;
grant create   session to dtstest;
grant LOGMINING TO dtstest;
-- v$logmnr_contents privileges
grant select on v_$logmnr_contents to dtstest;

Procedure

  1. Log on to the DTS console.
  2. In the left-side navigation pane, click Data Migration.
  3. At the top of Migration Tasks the page, select the region where the destination cluster resides.
    Select a region
  4. In the upper-right corner of the page, click Create Migration Task.
  5. Configure the source and destination databases for the data migration task.
    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 for easy identification. You do not need to use a unique task name.
    Source Database Instance Type Select an instance type based on where the source database is deployed. The procedure in this topic uses User-Created Database with Public IP Address as an example.
    Note If you select other instance types, you must prepare the environments that are required for the source database. For more information, see Preparation overview.
    Instance Region If the instance type is set to User-Created Database with Public IP Address, you do not need to specify the instance region.
    Note If a whitelist is configured for the user-created Oracle database, you must manually add the CIDR blocks of DTS servers to the whitelist of the user-created Oracle database. You can click Get IP Address Segment of DTS next to Instance Region to obtain the CIDR blocks of DTS servers.
    Database Type Select Oracle.
    Hostname or IP Address Enter the endpoint that is used to connect to the user-created Oracle database.
    Port Number Enter the service port number of the user-created Oracle database. The default port number is 1521.
    Note In this example, The service port of the user-created Oracle database is accessible over the Internet.
    Instance Type
    • Non-RAC Instance: If you select this option, you must specify the SID.
    • RAC Instance: If you select this option, you must specify the Service Name.
    Database Account Enter the account of the user-created Oracle database. For more information about the permissions that are required for the account, see #section_m4e_lp6_p1o.
    Database Password Enter the password for the source database account.
    Note After you specify the source database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the source database parameters based on the check results.
    Destination Database Instance Type Select PolarDB.
    Instance Region Select the region where the destination PolarDB cluster resides.
    PolarDB Instance ID Select the ID of the destination PolarDB cluster.
    Database Name Enter the name of the destination database.
    Database Account Enter the database account of the destination PolarDB cluster. For more information about the permissions that are required for the account, see #section_m4e_lp6_p1o.
    Database Password Enter the password for the destination database account.
    Note After you specify the destination database parameters, click Test Connectivity next to Database Password to verify whether the parameters are valid. If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the destination database parameters based on the check results.
  6. In the lower-right corner of the page, click Set Whitelist and Next.
    Note The CIDR blocks of DTS servers are automatically added to the whitelist of the destination PolarDB cluster. This ensures that DTS servers can connect to the destination PolarDB cluster.
  7. Select the migration types and objects to be migrated.
    Select the migration types and objects to be migrated
    Parameter Description
    Migration Types
    • To perform only full data migration, select Schema Migration and Full Data Migration.
    • To migrate data with minimal downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration.
    Note If Incremental Data Migration is not selected, do not write data into the source database during full data migration. This ensures data consistency between the source and destination databases.
    Objects

    Select objects from the Available section and click the Right arrow icon to move the objects to the Selected section.

    Note
    • You can select columns, tables, or databases as the objects to be migrated.
    • After an object is migrated to the destination database, the name of the object remains the same as that in the source database. You can change the names of the objects that are migrated to the destination database by using the object name mapping feature. For more information about how to use this feature, see Object name mapping.
    • If you use the object name mapping feature on an object, other objects that are dependent on the object may fail to be migrated.
  8. Click Precheck on the lower right of the page.
    Note
    • A precheck is performed for a data migration task. A data migration task can be started only if it passes the precheck.
    • If the precheck fails, click Note icon corresponding to each failed item to view the details. Fix the problems as instructed and run the precheck again.
  9. After the precheck is passed, click Next.
  10. On the Confirm Settings dialog box that appears, specify Channel Specification and select the Data Transmission Service (Pay-As-You-Go) Service Terms.
  11. Click Buy and Start to start the data migration task.
    • Schema migration and full data migration

      Do not manually stop a migration task. Otherwise, data migrated to the destination database will be incomplete. Wait until the data migration task stops when it is complete.

    • Schema migration, full data migration, and incremental data migration

      An incremental data migration task does not automatically end. You must manually end the migration task.

      Note Select an appropriate time point to manually end the migration task. For example, you can end the migration task during off-peak hours or before you switch your workloads to the destination cluster.
      1. When the task progress bar switches to Incremental Data Migration and the message The migration task is not delayed appears, stop writing new data to the source database for a few minutes. Then, the progress bar will show the latency of the incremental data migration.
      2. When the status of incremental data migration changes to The migration task is not delayed, manually stop the migration task.Stop the incremental migration task
  12. Switch your workloads to the destination cluster.