Oracle to Dameng Data Replication

NineData Data Replication supports schema replication, full replication, and incremental replication from Oracle to Dameng.

Overview

Use this guide to move Oracle data into Dameng or keep a Dameng database synchronized with ongoing Oracle changes. NineData can create target schemas, copy existing data, and continue applying incremental changes from Oracle logs after the initial replication completes.

Before you begin

Add the source and target data sources to NineData. For instructions, see Add Data Source.
The source data source is Oracle 23ai, 21c, 19c, 18c, 12c, or 11g. Supported Oracle editions include:
- Oracle Enterprise Edition
- Oracle Standard Edition
- Oracle Express Edition
- Oracle Personal Edition
The target data source is a Dameng database.

You must have the following permissions for the source and target data sources:

Replication Type	Source Data Source	Target Data Source
Structure Replication	select connect select any dictionary select any table select_catalog_role	ALL privileges on the database
Full Replication	select connect select any dictionary select any table select_catalog_role	ALL privileges on the database
Incremental Replication	See Appendix 2: Oracle incremental replication account permissions.	ALL privileges on the database

For incremental replication, configure the source Oracle database as follows:
- Set the Oracle log mode to ARCHIVELOG. The default mode is NOARCHIVELOG.
  To check the current log mode, run:
```
SELECT log_mode FROM v$database;
```
  If the log mode is NOARCHIVELOG, run the following commands:
```
SHUTDOWN IMMEDIATE;
STARTUP MOUNT;
ALTER DATABASE ARCHIVELOG;
ALTER DATABASE OPEN;
```
- Enable supplemental logging. It is disabled by default.
  To check whether supplemental logging is enabled, run:
```
SELECT supplemental_log_data_all allc FROM v$database;
```
  If the result is NO, use the command that applies to your scenario:
```
ALTER DATABASE ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS;
ALTER TABLE <database_name>.<table_name> ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS;
ALTER DATABASE ADD SUPPLEMENTAL LOG DATA;
```
  ALTER DATABASE ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS enables database-level supplemental logging and can consume more resources. ALTER TABLE <database_name>.<table_name> ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS enables supplemental logging for a specific table.

Restrictions

Before you run a replication task, assess the performance of the source and target data sources. Run the task during off-peak hours when possible because full initialization consumes read and write resources.
Each replicated table must have a primary key or unique constraint, and column names must be unique. Otherwise, duplicate rows may be replicated.

Procedure

Sign in to the NineData Console.
In the left navigation pane, click Replication > Data Replication.
On the Replication page, click Create Replication.

On the Source & Target tab, configure the fields in the table, and click Next.

Parameter	Description
Name	Enter a name for the data synchronization task. To make the task easier to find and manage later, use a meaningful name. Up to 64 characters are supported.
Source	The data source that contains the objects to synchronize.
Datahub Project	Select the target Datahub Project. Data from the source data source will be written to the specified Project.
Type	Select the replication type. Schema: Synchronize only the database and table schemas of the source data source, without synchronizing data. Full: Synchronize all objects and data from the source data source, namely full data replication. The switch on the right enables periodic full replication. For more information, see Periodic Full Replication. Incremental: After full synchronization is complete, perform incremental synchronization based on the logs of the source data source.The icon is used to configure incremental operation types. You can clear specific operation types as needed. Cleared operation types will be ignored during incremental synchronization.
Incremental Started	Required only when Type is Incremental. From Started: Use the current replication task start time as the baseline for incremental replication. Customized Time: Select the point in time from which incremental replication starts. You can select a time zone based on the region of your business. If the configured time point is earlier than the current replication task start time and DDL operations occurred during that period, the replication task will fail.
Spec (Unavailable only when Schema is selected)	The specification of the replication task. A larger specification provides a higher replication rate. Hover over the icon to view the rate and configuration information of each specification. Each specification shows the available quantity and total quantity. When the available quantity is 0, the specification is grayed out and cannot be selected.
If target table already exists (Required when Schema is selected)	Pre-Check Error and Stop Task: Stop the task when a table with the same name is detected during the precheck stage. Skip and Continue Task: When a table with the same name is detected during the precheck stage, display a message and continue the task. During schema replication, ignore the table with the same name. If you also perform data replication, data is appended to the table with the same name and existing data is not overwritten. Delete Objects and Rewrite: When a table with the same name is detected during the precheck stage, display a message and continue the task. During schema replication, delete the table with the same name in the target database and replicate the table schema again based on the source database. If you also perform data replication, data is written after schema replication is complete.
Target Table Exists Data (Required when Full is selected)	Pre-Check Error and Stop Task: Stop the task when data is detected in the target table during the precheck stage. Ignore existing target data and append to it.: When data is detected in the target table during the precheck stage, ignore that data and append other data. Clear target existing data before write: When data is detected in the target table during the precheck stage, delete that data and write it again.
Incremental data conflict handling strategy for target table (Required when Incremental is selected)	Runtime error: During incremental replication, report an error when target data already exists and wait for manual intervention. Do not update target data: During incremental replication, do not write data when target data already exists, and continue subsequent tasks. Update target data: During incremental replication, overwrite the target data when target data already exists.

On the Objects tab, configure the parameters in the table, and click Next.

Parameter	Description

To create multiple replication tasks with the same replication objects, import a configuration file. Click Import Config, click Download Template to download the template, edit the file, and then click Upload to upload it and import the objects in bulk. The configuration file uses these fields:

Parameter	Description
`source_table_name`	The source table name of the object to synchronize.
`destination_table_name`	The target table name that receives the synchronized object.
`source_schema_name`	The source schema name of the object to synchronize.
`destination_schema_name`	The target schema name that receives the synchronized object.
`source_database_name`	The source database name of the object to synchronize.
`target_database_name`	The target database name that receives the synchronized object.
`column_list`	The list of columns to synchronize.
`extra_configuration`	Additional configuration information. This field supports: `column_rules`: Defines column mappings and value rules. Field descriptions: `column_name`: Original column name. `destination_column_name`: Specifies the target column name. `column_value`: Specifies the column value, which can be an SQL function or a constant value. `filter_condition`: Specifies row-level data filtering conditions. Only rows that meet the conditions are replicated.

tip

Example of extra_configuration:

{
  "extra_config":{
    "column_rules":[
      {
         "column_name": "created_time",
         "destination_column_name": "migrated_time",
         "column_value": "current_timestamp()"
      }
    ],
     "filter_condition": "id != 0"
  }
}

In this example, created_time is mapped to migrated_time, the target column value is changed to current_timestamp(), and only rows whose id value is not 0 are synchronized.

For a complete example of the configuration file, see the downloaded template.

On the "Mapping" tab, configure the mapping that matches the selected replication type, then click Save and Pre-Check. If source or target metadata changes while you configure mappings, click Refresh Metadata to refresh the metadata.
- Includes Schema: Configure the table name after synchronization to the target data source.
- Does not include Schema: The system selects the database with the same name in the target data source by default. If no such database exists, select the target database manually. The table names and column names in the target database must match the synchronization objects. If they do not match, map the table names and column names manually.
You can also perform these actions:
- Click Mapping & Filtering to customize the column names after synchronization to the target data source.
- On the Mapping & Filtering page, click Data Filter to configure filtering conditions by using comparison expressions. Only data that meets the filtering conditions is synchronized to the target data source. For example, if the filtering condition is set to emp_no>=10005, data whose emp_no column value is less than 10005 is not synchronized to the target data source.
- Click the icon to the right of "Target Table" to search for a table name and replace it with the target name.
- Enter a table name in the Search Table text box to quickly locate the target table.
- Click Batch Configuration to define common rules in batches, such as table name and column name case conversion, prefix or suffix addition, and replacement. Use this option to apply mapping configuration to many tables and columns at the same time.

You can also perform these actions:

Click Mapping & Filtering to customize target column names after synchronization.
On the Mapping & Filtering page, enter a comparison expression in the text box below Data Filter as the filtering condition. Only data that meets the filtering condition is synchronized to the target data source. For example, if the filtering condition is emp_no>=10005, data whose emp_no column value is less than 10005 is not synchronized to the target data source.
Click the icon next to "Target Table" to search for table names and replace them with target names.
Enter a table name in the Search Table text box to quickly locate the target table.
Click Batch Configuration to define common rules in batches, such as table or column name case conversion, prefix or suffix addition, and replacement. Use batch rules to apply consistent mapping to a large number of tables and columns.

On the Pre-check tab, wait for the system to complete the precheck. After the precheck passes, click Launch.
- Select Enable data consistency comparison to start a data consistency comparison task based on the source data source after synchronization completes. Based on the selected Type, Enable data consistency comparison starts at these times:
  - Schema: Starts after schema replication is complete.
  - Schema+Full: Starts after full replication is complete.
  - Full: Starts after full replication is complete.
  - Schema+Full+Incremental, Incremental: Starts when incremental data is consistent with the source data source for the first time and Delay is 0 seconds. Click View Details to view synchronization delay on the Details page.
- If the precheck fails, click Details in the Actions column for the failed check item, review the cause, fix the issue, and then click Check Again to run the precheck again until it passes.
- Items with Warning in Result can be fixed or ignored as needed.
On the Launch page, the Launch Successfully message appears, indicating that the synchronization task has started. You can then perform these actions:
- Click View Details to view the execution status of each stage of the synchronization task.
- Click Back to list to return to the Replication task list page.

View replication results

Sign in to the NineData Console.
Click Replication > Data Replication in the navigation menu.

On the Replication page, click the Task ID of the target synchronization task. The task details page shows the following areas.

oracle_result

No.	Function	Description
1	Synchronization Delay	Shows the synchronization delay between the source and target data sources. A value of 0 seconds means there is no delay between source and target.
2	Configure Alerts	Configure alerts to receive failure notifications through your chosen method. For more information, see Introduction to Operations Monitoring.
3	More	Pause: Pause a task whose status is Running. Terminate: Terminate a task that is unfinished or still being monitored, such as a task in incremental synchronization. A terminated task cannot be restarted. Proceed with caution. If the synchronization object includes triggers, trigger replication options appear. Choose the option that matches your task. Delete: Delete the task. Deleted tasks cannot be recovered. Proceed with caution.
4	Structure Replication (shown when structure replication is included)	Shows structure replication progress and details. Click Logs to view structure replication logs. Click to view the latest information. Click View DDL in the Operations column for a target object to view the SQL replay.
5	Full Replication (shown when full replication is included)	Shows full replication progress and details. Click Monitoring to view monitoring metrics during full replication. During full replication, click Throttle Settings on the monitoring page to limit the write rate to the target data source. Click Logs to view full replication logs. Click to view the latest information.
6	Incremental Replication (shown when incremental replication is included)	Shows incremental replication metrics. Click View Threads to view the operations currently running in the replication task, including: Thread ID: The replication task uses multiple threads, and this item shows the current thread number. Execute SQL: Details of the SQL statement currently being executed by the current thread. Response Time: The response time of the current thread. If this value increases, the thread may be blocked. Event Time: The timestamp when the current thread started. Status: The status of the current thread. Click Throttle Settings to limit the write rate to the target data source. The unit is rows per second. Click Logs to view incremental replication logs. Click to view the latest information.
7	Modify Objects	Shows the modification history of synchronization objects. Click Modify Synchronization Objects to configure synchronization objects. Click to view the latest information.
8	Data Comparison	Shows the results of data comparison between the source and target data sources. This includes Structure Comparison and Data Comparison. If data comparison is not enabled, click Enable Data Comparison on the page. Click Re-compare to start the comparison again for the current source and target data. Click the date to view all comparison results, then click a target list item to open that comparison result's details. Click Logs to view consistency comparison logs. Click Monitoring (shown only for data comparison) to view the comparison RPS trend chart. Click Details to view earlier records. Click in the Operations column of the comparison list to view source and target comparison details. Click in the Operations column of the comparison list (shown when data is inconsistent) to generate change SQL. Copy this SQL to the target data source and run it to fix the inconsistency.
9	Expand	Shows detailed information about the current replication task, including Replication Type, Replication Objects, Start Time, and more.

Appendix 1: Precheck items

Check item	What NineData checks
Source table key check	Checks whether the source objects to replicate include tables without a primary key or unique key.
Source data source connection check	Checks the source gateway status, database connectivity, and username and password.
Target data source connection check	Checks the target gateway status, database connectivity, and username and password.
Target database permission check	Checks whether the target database account has the required permissions.
Source database permission check	Checks whether the source database account has the required permissions.
Target database data existence check	Checks whether target objects already contain data.
Target same-name object check	Checks whether objects with the same names already exist in the target database.
Cyclic replication check	Checks whether the selected source and target configuration may create a replication loop.
Source database archive log mode check	Checks whether the source database log mode is `ARCHIVELOG`.
Source database supplemental logging check	Checks whether supplemental logging is enabled and set to `ALL`.

Appendix 2: Oracle incremental replication account permissions

Below Oracle 12c
Oracle 12c and above

Designate a user with DBA privileges for incremental data replication tasks with Oracle as the source.

-- Create NineData sync account
CREATE USER test_dba IDENTIFIED BY "ninedatasync";
-- Grant DBA privileges to the account
GRANT dba to test_dba;

Designate a user with DBA privileges for incremental data replication tasks with Oracle as the source.

-- Create NineData sync account in the global environment
CREATE USER c##test_dba IDENTIFIED BY "ninedatasync";
-- Grant DBA and connect privileges to the account, specifying the scope of the privileges
GRANT dba, connect to c##nine_data container=all;

Introduction to Data Replication

Oracle to Dameng Data Replication

Overview​

Before you begin​

Restrictions​

Procedure​

View replication results​

Appendix 1: Precheck items​

Appendix 2: Oracle incremental replication account permissions​

Related documents​