From Oracle to GaussDB Primary/Standby
Supported Source and Destination Databases
Source DB |
Destination DB |
---|---|
|
GaussDB Primary/Standby (1.0.0 and later versions) |
Database Account Permission Requirements
To start a synchronization task, the source and destination database users must meet the requirements in the following table. Different types of synchronization tasks require different permissions. For details, see Table 2. DRS automatically checks the database account permissions in the pre-check phase and provides handling suggestions.
Type |
Full Synchronization |
Full+Incremental Synchronization and Incremental Synchronization |
---|---|---|
Source database user |
|
|
Destination database user |
|
- You are advised to create an independent database account for DRS task connection to prevent task failures caused by database account password modification.
- After changing the account passwords for the source and destination databases, modify the connection information of the DRS task by referring to Modifying Connection Information to prevent automatic retry after a task failure. Automatic retry will lock the database accounts.
Supported Synchronization Objects
Table 3 lists the objects that can be synchronized in different scenarios. DRS will automatically check the objects you selected before the synchronization.
Type |
Precautions |
---|---|
Synchronization objects |
|
Precautions
To ensure tasks can run normally, DRS provides automatic pre-check. Before starting a DRS task, DRS checks the configurations and conditions of the source and destination databases. For details about the main check items and handling suggestions, see Pre-check Items. In addition to the pre-check items, you need to pay attention to the items listed in Table 4.
Type |
Restrictions |
---|---|
Restrictions on the source database |
|
Restrictions on usage |
General
Full synchronization
Incremental synchronization
Troubleshooting
|
Other restrictions |
|
Procedure
- On the Data Synchronization Management page, click Create Synchronization Task.
- On the Create Synchronization Instance page, select a region and project, specify the task name, description, and the synchronization instance details, and click Create Now.
- Task information description
Figure 1 Synchronization task information
Table 5 Task information Parameter
Description
Region
The region where the replication instance is deployed. You can change the region.
Project
The project corresponds to the current region and can be changed.
Task Name
The task name must start with a letter and consist of 4 to 50 characters. It can contain only letters, digits, hyphens (-), and underscores (_).
Description
The description consists of a maximum of 256 characters and cannot contain special characters !=<>'&"\
- Synchronization instance details
Figure 2 Synchronization instance details
Table 6 Synchronization instance settings Parameter
Description
Data Flow
Select To the cloud.
Source DB Engine
Select Oracle.
Destination DB Engine
Select GaussDB Primary/Standby.
Network Type
Public network is used as an example. Available options: VPC, Public network and VPN or Direct Connect
- VPC is suitable for data synchronization between cloud databases of the same account in the same region and VPC.
- Public network is suitable for data synchronization from on-premises or external cloud databases to the destination databases bound with an EIP.
- VPN or Direct Connect is suitable for data synchronization from on-premises databases to cloud databases, between databases of different accounts in the same region on the cloud, or between databases across regions on the cloud using a VPN, Direct Connect, Cloud Connect, VPCEP, or a VPC peering connection.
DRS Task Type
Type of the DRS task. The value can be Single-AZ or Dual-AZ.
- Dual-AZ: This architecture provides HA, improving the reliability of DRS tasks. After a dual-AZ task is created, DRS creates two subtasks, each running in the primary and standby AZs. If the subtask in the primary AZ fails, DRS automatically starts the subtask in the standby AZ to continue the synchronization. This deployment is for scenarios where there is a lot of service data, long-term synchronization is required, and there are strict limits on how much service downtime can be tolerated.
- Single-AZ: Single-node deployment is used. The synchronization task will be created on only one node to save money. This deployment is for scenarios where there is a small amount of service data, short-term synchronization is required, and there is no requirement on service downtime.
This option is available only in specific scenarios. For details, see Performing a Switchover for a Dual-AZ Task.
Destination DB Instance
The GaussDB primary/standby instance you created.
Synchronization Instance Subnet
Select the subnet where the synchronization instance is located. You can also click View Subnets to go to the network console to view the subnet where the instance resides.
By default, the DRS instance and the destination DB instance are in the same subnet. You need to select the subnet where the DRS instance resides, and there are available IP addresses for the subnet. To ensure that the synchronization instance is successfully created, only subnets with DHCP enabled are displayed.
Synchronization Mode
The synchronization mode supported by a DRS task. Full+Incremental is used as an example. For details about the underlying working principles for full or incremental synchronization, see Product Architecture and Function Principles.
Specify EIP
This parameter is available when you select Public network for Network Type. Select an EIP to be bound to the DRS instance. DRS will automatically bind the specified EIP to the DRS instance and unbind the EIP after the task is complete.
If DRS Task Type is set to Dual-AZ, you need to specify the primary and standby IP addresses.
For details about the data transfer fee generated using a public network, see EIP Price Calculator.
- Task Type
Figure 3 Task type
Table 7 Task type information Parameter
Description
Specifications
DRS instance specifications. Different specifications have different performance upper limits. For details, see Real-Time Synchronization.
NOTE:DRS allows you to upgrade specifications only for single-AZ synchronization tasks. Task specifications cannot be downgraded. For details, see Changing Specifications.
AZ
Select the AZ where you want to create the DRS task. Selecting the one housing the source or destination database can provide better performance.
If DRS Task Type is set to Dual-AZ, you can specify Primary AZ and Standby AZ.
Figure 4 AZ
- Enterprise Project and Tags
Figure 5 Enterprise projects and tags
Table 8 Enterprise Project and Tags Parameter
Description
Enterprise Project
An enterprise project you would like to use to centrally manage your cloud resources and members. Select an enterprise project from the drop-down list. The default project is default.
For more information about enterprise project, see Enterprise Management User Guide.
To customize an enterprise project, click Enterprise in the upper right corner of the console. The Enterprise Project Management Service page is displayed. For details, see Creating an Enterprise Project in Enterprise Management User Guide.
Tags
- Tags a task. This configuration is optional. Adding tags helps you better identify and manage your tasks. Each task can have up to 20 tags.
- If your organization has configured tag policies for DRS, add tags to tasks based on the policies. If a tag does not comply with the policies, task creation may fail. Contact your organization administrator to learn more about tag policies.
- After a task is created, you can view its tag details on the Tags tab. For details, see Tag Management.
If a task fails to be created, DRS retains the task for three days by default. After three days, the task automatically stops.
- Task information description
- On the Configure Source and Destination Databases page, specify source and destination database information and click Test Connection for both the source and destination databases to check whether they have been connected to the synchronization instance. After the connection tests are successful, click Next.
Figure 6 Source database information
Table 9 Source database settings Parameter
Description
IP Address or Domain Name
The IP address or domain name of the source database.
NOTE:For a RAC cluster, use a Scan IP address to improve access performance.
Port
The port of the source database. Range: 1 – 65535
Database Service Name
Enter a database service name (Service Name/SID). The client can connect to the Oracle database through the database service name. For details about how to query the database service name, see the prompt on the GUI.
PDB Name
Container database (CDB) and pluggable database (PDB) are new features in Oracle 12c and later versions. This function is optional, but it must be enabled if you want to migrate only PDB tables.
Enter the service name, SID, username, and password of the CDB that contains the PDB tables to be migrated.
Database Username
The username for accessing the source database.
Database Password
The password for the database username.
SSL Connection
SSL encrypts the connections between the source and destination databases. If SSL is enabled, upload the SSL CA root certificate.
NOTE:- The maximum size of a single certificate file that can be uploaded is 500 KB.
- If SSL is disabled, your data may be at risk.
Figure 7 Destination database information
Table 10 Destination database settings Parameter
Description
DB Instance Name
The GaussDB primary/standby instance selected during synchronization task creation. This parameter cannot be changed.
Database Username
The username for accessing the destination database.
Database Password
The password for the database username. The database username and password are encrypted and stored in the system and will be cleared after the task is deleted.
- On the Set Synchronization Task page, select the synchronization object, enter the name of the destination database, and click Next.
Figure 8 Synchronization mode
Table 11 Synchronization Object Parameter
Description
Flow Control
You can choose whether to control the flow. Flow Control takes effect in the full phase only.
- Yes
You can customize the maximum synchronization speed. During the full synchronization, the synchronization speed of each task (or each subtask in multi-task mode) does not exceed the value of this parameter.
In addition, you can set the time range based on your service requirements. The traffic rate setting usually includes setting of a rate limiting time period and a traffic rate value. Flow can be controlled all day or during specific time ranges. The default value is Always. A maximum of three time ranges can be set, and they cannot overlap.
The flow rate must be set based on the service scenario and cannot exceed 9,999 MB/s.
Figure 9 Flow control
- No
The synchronization speed is not limited and the outbound bandwidth of the source database is maximally used, which will increase the read burden on the source database. For example, if the outbound bandwidth of the source database is 100 MB/s and 80% bandwidth is used, the I/O consumption on the source database is 80 MB/s.NOTE:
- The flow control mode takes effect only in the full synchronization phase.
- You can also change the flow control mode after creating a task. For details, see Modifying the Flow Control Mode.
Sharding Mode
Select Sharding by primary key or Sharding by row ID as needed.
- Sharding by primary key
Tables with primary keys are sharded using primary key values. The sharding efficiency is lower than that of Sharding by row ID.
- Sharding by row ID
Sharding by row ID is recommended for synchronizing large tables without primary keys, improving sharding efficiency.
Restrictions on Sharding by row ID: During full synchronization, do not perform operations that will cause row ID changes on the source database, such as Export/import of the table, ALTER TABLE XXXX MOVE, ALTER TABLE XXXX SHRINK SPACE, FLASHBACK TABLE XXXX, Splitting a partition, Updating a value so that it moves to a new partition, or Combining two partitions. Otherwise, data may be inconsistent. You can run ALTER TABLE XXXX DISABLE ROW MOVEMENT to disable these operations.
Synchronize
Incremental DDL synchronization is supported. You can determine whether to synchronize DDLs based on service requirements.
Synchronize DML
Select the DML operations to be synchronized. By default, all DML operations are selected.
If you do not select Delete, DELETE statements in the incremental data of the source database will not be synchronized, which may cause a data inconsistency. As a result, there may be a data conflict or the task may fail.
Incremental Read Mode
Select the mode of reading logs in the incremental synchronization phase.
- LogMiner: uses the official Oracle interface to read redo logs. This mode is stable.
- Binary Reader: uses DRS-developed method to directly read and parse original redo logs. The performance is high, and the Oracle resource consumption is low.
LogMiner is recommended.
Synchronize DDLs
This parameter is available when Incremental DDLs is selected for Synchronize. Select DDL type for incremental synchronization. You can select Default or Custom based on your service requirements.
- Default
During table-level synchronization, only DDLs of the selected tables will be synchronized to the destination. The supported DDL statements are CREATE_TABLE, ALTER_TABLE, and TRUNCATE_TABLE.
- Custom: You can select the DDL type to be synchronized as required. The DDL types supported by different data flow types are displayed on the GUI.
Synchronization Object
The left pane displays the source database objects, and the right pane displays the selected objects. You can select Tables or Import object file for Synchronization Object as required.
- If the synchronization objects in source and destination databases have different names, you can map the source object name to the destination one. For details, see Changing Object Names (Mapping Object Names).
- For details about how to import an object file, see Importing Synchronization Objects.
NOTE:- To quickly select the desired database objects, you can use the search function.
- If there are changes made to the source databases or objects, click in the upper right corner to update the objects to be synchronized.
- If an object name contains spaces, the spaces before and after the object name are not displayed. If there are two or more consecutive spaces in the middle of the object name, only one space is displayed.
- The name of the selected synchronization object cannot contain spaces.
- Yes
- On the Process Data page, set the filtering rules for data processing.
- If data processing is not required, click Next.
- If you need process columns or filter out data, set the corresponding rules by referring to Processing Data.
Figure 10 Processing data
- On the Check Task page, check the synchronization task.
- If any check fails, review the cause and rectify the fault. After the fault is rectified, click Check Again.
For details about how to handle check failures, see Solutions to Failed Check Items in Data Replication Service User Guide.
- If all check items are successful, click Next.
You can proceed to the next step only when all checks are successful. If there are any items that require confirmation, view and confirm the details first before proceeding to the next step.
- If any check fails, review the cause and rectify the fault. After the fault is rectified, click Check Again.
- On the displayed page, specify Start Time, Send Notifications, SMN Topic, Delay Threshold (s), and Stop Abnormal Tasks After, confirm that the configured information is correct, select the check box before the agreement, and click Submit to submit the task.
Figure 11 Task startup settings
Table 12 Task startup settings Parameter
Description
Start Time
Set Start Time to Start upon task creation or Start at a specified time based on site requirements.
NOTE:After a synchronization task is started, the performance of the source and destination databases may be affected. You are advised to start a synchronization task during off-peak hours.
Send Notifications
This parameter is optional. After enabled, select a SMN topic. If the status, latency metric, or data of the migration task is abnormal, DRS will send you a notification.
SMN Topic
This parameter is available only after you enable Send Notifications and create a topic on the SMN console and add a subscriber.
For details, see Simple Message Notification User Guide.
Delay Threshold (s)
During an incremental synchronization, a synchronization delay indicates a time difference (in seconds) of synchronization between the source and destination database.
If the synchronization delay exceeds the threshold you specify, DRS will send alarms to the specified recipients. The value ranges from 0 to 3,600. To avoid repeated alarms caused by the fluctuation of delay, an alarm is sent only after the delay has exceeded the threshold for six minutes.
NOTE:- If the delay threshold is set to 0, no notifications will be sent to the recipient.
- In the early stages of an incremental synchronization, the synchronization delay is long because a large quantity of data is awaiting synchronization. In this case, no notifications will be sent.
- Before setting the delay threshold, enable Send Notifications.
Data Exception Notification
This parameter is optional. After enabled, DRS will send a notification if the task data is abnormal.
Stop Abnormal Tasks After
Number of days after which an abnormal task is automatically stopped. The value must range from 14 to 100. The default value is 14.
NOTE:- You can set this parameter only for pay-per-use tasks.
- Tasks in the abnormal state are still charged. If tasks remain in the abnormal state for a long time, they cannot be resumed. Abnormal tasks run longer than the period you set (unit: day) will automatically stop to avoid unnecessary fees.
- After the task is submitted, you can view and manage it on the Data Synchronization Management page.
- You can view the task status. For more information about task status, see Task Statuses.
- You can click in the upper right corner to view the latest task status.
- By default, DRS retains a task in the Configuration state for three days. After three days, DRS automatically deletes background resources, but the task status remains unchanged. When you configure the task again, DRS applies for resources for the task again. In this case, the IP address of the DRS instance changes.
- For a public network task, DRS needs to delete background resources after you stop the task. The EIP bound to the task cannot be restored to the Unbound state until background resources are deleted.
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