This topic describes how to use OceanBase Migration Service (OMS) Community Edition to migrate data from a PostgreSQL database to OceanBase Community Edition.
Background
You can create a data migration project in the OMS Community Edition console to migrate the existing business data and incremental data from a PostgreSQL database to OceanBase Community Edition through schema migration, full migration, and incremental synchronization.
The PostgreSQL database supports the following modes: primary database only, standby database only, and primary/standby databases. The following table describes the data migration operations supported by each mode.
| Type | Supported operations |
|---|---|
| Primary database only | Schema migration, full migration, incremental synchronization, full verification, and reverse incremental migration |
| Standby database only | Schema migration, full migration, and full verification |
| Primary/standby databases | Primary database: incremental synchronization and reverse incremental migration Standby database: schema migration, full migration, and full verification |
Prerequisites
You have created a corresponding schema in the destination MySQL tenant of OceanBase Database. OMS Community Edition allows you to migrate tables and columns. Therefore, you must create a corresponding schema in the destination database before migration.
You have created dedicated database users in the source PostgreSQL database and the destination MySQL tenant of OceanBase Database for data migration and granted the corresponding privileges to the users. For more information, see Create a database user.
Limits
PostgreSQL 10.x is supported.
OMS Community Edition allows you to migrate tables with primary keys and tables with NOT NULL unique keys from a PostgreSQL database to OceanBase Community Edition.
When you use OMS Community Edition to migrate data from a PostgreSQL database to OceanBase Community Edition, DDL synchronization is not supported.
OMS Community Edition does not support triggers in the destination database.
When you migrate partitioned tables from a PostgreSQL database, note the following limits:
The parent table and child table must have the same schema.
The parent table and child table must have the same primary key columns, NOT NULL unique key columns, and partitioning key columns, or the primary key columns or NOT NULL unique key columns must include the partitioning key columns.
The primary keys or NOT NULL unique keys must be unique in the parent table.
REPLICA IDENTITY must be set to FULL for all parent tables and child tables to be migrated from the PostgreSQL database.
OMS Community Edition does not support the migration of unlogged tables and temporary tables in the PostgreSQL database.
If the database contains a multi-partition table that has a globally unique index, data may be lost during migration if you update the value of the partitioning key of the table.
If you change the unique index of the destination, you must restart the incremental synchronization. Otherwise, the data may be inconsistent.
Data type mappings
| PostgreSQL database | OceanBase Community Edition |
|---|---|
| bigint | BIGINT |
| bigserial | BIGINT |
| bit [(n)] | BIT |
| boolean | TINYINT(1) |
| box | POLYGON |
| bytea | LONGBLOB |
| character [(n)] | CHAR LONGTEXT |
| character varying [(n)] | VARCHAR MEDIUMTEXT LONGTEXT |
| cidr | VARCHAR(43) |
| circle | POLYGON |
| date | DATE |
| double precision | DOUBLE |
| inet | VARCHAR(43) |
| interval [fields] [(p)] | TIME |
| json | LONGTEXT JSON |
| jsonb | LONGTEXT JSON |
| line | LINESTRING |
| lseg | LINESTRING |
| macaddr | VARCHAR(17) |
| money | DECIMAL(19,2) |
| numeric [(p, s)] | DECIMAL |
| path | LINESTRING |
| real | FLOAT |
| smallint | SMALLINT |
| smallserial | SMALLINT |
| serial | INT |
| text | LONGTEXT |
| time [(p)] [without time zone] | TIME |
| time [(p)] with time zone | TIME |
| timestamp [(p)] [without time zone] | DATETIME |
| timestamp [(p)] with time zone | DATETIME |
| tsquery | LONGTEXT |
| tsvector | LONGTEXT |
| uuid | VARCHAR(36) |
| xml | LONGTEXT |
| point | POINT |
| linestring | LINESTRING |
| polygon | POLYGON |
| multipoint | MULTIPOINT |
| multilinestring | MULTILINESTRING |
| multipolygon | MULTIPOLYGON |
| geometrycollection | GEOMETRYCOLLECTION |
| triangle | POLYGON |
| tin | MULTIPOLYGON |
Create a data migration project
Create a migration project.
Log on to the OMS Community Edition console.
In the left-side navigation pane, click Data Migration.
On the Data Migration page, click Create Migration Project in the upper-right corner.
On the Select Source and Destination page, configure the parameters.
Parameter Description Migration Project Name We recommend that you set it to a combination of digits and letters. It must not contain any spaces and cannot exceed 64 characters in length. Label Click the field and select a target tag from the drop-down list. You can click Manage Tags to create, modify, and delete tags. For more information, see Use tags to manage data migration projects. Source If you have created a PostgreSQL data source, select it from the drop-down list. Otherwise, click Create Data Source in the drop-down list and create a data source in the dialog box that appears on the right. For more information, see Create a PostgreSQL data source.
You can select a PostgreSQL data source in primary database only mode or primary/standby databases mode. This topic describes how to create a data migration project with a PostgreSQL data source in primary/standby databases mode.Destination If you have created a data source for the MySQL tenant of OceanBase Database, select it from the drop-down list. Otherwise, click Create Data Source in the drop-down list and create a data source in the dialog box that appears on the right. For more information, see Create OceanBase-CE data source.
Notice: The destination database cannot be OceanBase Community Edition V4.0.0-CE.Click Next.
In the dialog box that appears, click OK.
Note that this project supports only tables with a primary key or a non-null unique index and other tables are automatically filtered out.
On the Select Migration Type page, specify related parameters.
Options are available for Migration Type include Schema Migration, Full Migration, Incremental Synchronization, Full Verification, and Reverse Incremental Migration.
Migration type Limits Full Migration If you select Full Migration, we recommend that you use the ANALYZEstatement to collect the statistics of the PostgreSQL database before data migration.Incremental Synchronization Incremental Synchronization supports the following DML statements for data synchronization: INSERT,DELETE, andUPDATE. You can select statements based on your business needs.Full Verification - If you select Full Verification, we recommend that you collect the statistics of the PostgreSQL database and the MySQL tenant of OceanBase Database before full verification.
- If you have selected Incremental Synchronization but did not select all DML statements in DML Synchronization, OMS Community Edition does not support full data verification in this scenario.
- OMS Community Edition supports full data verification of only tables with a unique key.
Reverse Incremental Migration You cannot select Reverse Incremental Migration in the following cases: - Multi-table aggregation and synchronization is enabled.
- Multiple schemas are configured in a rule to match one type of objects.
(Optional) Click Next. If you select Reverse Incremental Migration but the ConfigUrl, username, or password is not configured for the data source of the destination MySQL tenant of OceanBase Database, the More about Data Sources dialog box appears, prompting you to configure related parameters. For more information, see Create a physical data source of OceanBase Database.
After you configure the parameters, click Test Connectivity. After the test succeeds, click Save.
Click Next. On the Select Migration Objects page, select the migration objects and migration scope.
You can select one of the following two modes to migrate objects: Specify Objects or Match Rules.
Select Specify Objects. Then select the objects to be migrated on the left and click > to add them to the list on the right. You can select tables and views of one or more databases as the migration objects.
Notice:
The name of a table to be migrated and the names of columns in the table must not contain Chinese characters.
If the database or table name contains a double dollar sign ($$), you cannot create the migration project.
When you migrate data from a PostgreSQL database to OceanBase Community Edition, OMS allows you to import objects from text, rename object names, set row filters, view column information, and remove a single object or all objects to be migrated.
Operation Steps Import Objects - In the list on the right of the Specify Migration Scope section, click Import Objects in the upper-right corner.
- In the dialog box that appears, click OK.
Notice:
This operation will overwrite previous selections. Proceed with caution. - In the Import Objects dialog box, import the objects to be migrated.
You can import CSV files to rename databases/tables and set row filtering conditions. For more information, see Download and import the settings of migration objects. - Click Validate.
- After the validation succeeds, click OK.
Rename - In the list on the right of the Specify Migration Scope section, hover the pointer over the target object.
- Click Rename.
- Enter a new name and click OK.
Settings OMS Community Edition allows you to set WHEREconditions to filter data by row and view column information.- In the list on the right of the Specify Migration Scope section, hover the pointer over the target object.
- Click Settings.
- In the Settings dialog box, specify a standard SQL
WHEREclause to filter data by row. Its effective scope includes both full migration and incremental synchronization.
Notice:- Add an escape character (
\) for column names, for example,\col\. - Only the data meeting the
WHEREcondition is synchronized to the destination data source, thereby filtering data by row. - If row-based filtering with the
WHEREclause is enabled, right-trim is forcibly performed on data of the CHAR or VARCHAR type, which may cause an inaccurate comparison of the VARCHAR data. Proceed with caution.
- Add an escape character (
- Click OK.
You can also view column information of the migration object in the View Columns section.
Remove/Remove All OMS Community Edition allows you to remove one or multiple objects from the selected objects in the destination database during data mapping. - To remove a single migration object:
In the list on the right of the Specify Migration Scope section, hover the pointer over the target object, and click Remove. - To remove all migration objects:
In the list on the right of the Specify Migration Scope section, click Remove All in the upper-right corner. In the dialog box that appears, click OK.
Select Match Rules. For more information, see Configure matching rules for migration objects.
Click Next. On the Migration Options page, configure the parameters.
Parameter Description Concurrency for Full Migration The value can be Smooth, Normal, or Fast. The quantity of resources to be consumed by a full data migration task varies based on the migration performance.
You can also modify the configurations of the Checker-Full component to customize the concurrency.
Notice:
To enable this feature, select Full Migration on the Select Migration Type page.Full Verification Concurrency The value can be Smooth, Normal, or Fast. Different quantities of resources of the source and destination databases are consumed at different concurrences.
You can also modify the configurations of the Checker-Verify component to customize the concurrency.Incremental Record Retention Time The duration that incremental parsed files are cached in OMS Community Edition. A longer retention period indicates more disk space occupied by the Store component of OMS Community Edition. Whether to Allow Destination Table to Be Not Empty During Full Migration If destination tables are allowed to be not empty during full migration, full verification is performed in INmode.
Notice:
To enable this feature, select Full Migration on the Select Migration Type page.Whether to Allow Post-indexing You can specify whether to allow post-indexing after full migration is completed. Post-indexing can shorten the time of full migration.
Notice:- To enable this feature, select both Schema Migration and Full Migration on the Select Migration Type page.
- Only non-unique key indexes can be created after the migration is completed.
Click Precheck to start a precheck on the data migration project.
During the precheck, OMS Community Edition checks the read and write privileges of the database users and the network connections of the databases. The data migration project can be started only after it passes all check items. If the precheck fails:
You can identify the cause, fix the problem, and run the precheck again until it succeeds.
You can also click Skip in the Actions column of the failed precheck item. A dialog box then appears, showing the impact of skipping this operation. If you confirm to skip this operation, click OK in the dialog box.
Click Start Project. If you do not need to start the project now, click Save to go to the details page of the data migration project. You can start the project later as needed.
OMS Community Edition allows you to modify migration objects when a data migration project is running. For more information, see View and modify migration objects. After a data migration project is started, the migration objects will be executed based on the selected migration type. For more information, see the "View migration details" section in the View details of a data migration project.