MongoDB to PolarDb for MySQL
BladePipe supports data replication from MongoDB to PolarDb for MySQL. View supported migration, sync, verification, and connector capabilities.
| Function | Description |
|---|---|
Full Data Migration | Migrate data by sequentially scanning data in tables and writing it in batches to the target database. Supported _id types: ObjectId, Long, Integer. |
Incremental Data Sync | Sync of INSERT, UPDATE, DELETE is supported. |
Data Verification and Correction | Verify all existing data. Optionally, you can correct the inconsistent data based on verification results. Scheduled DataTasks are supported. |
Subscription Modification | Add, delete, or modify the subscribed tables with support for historical data migration. For more information, see Modify Subscription. |
Position Resetting | Reset positions by timestamp to consume the oplog in a past period again. |
Supported Deployment | Support master-slave, replica set, sharded cluster. |
Advanced Functions
| Function | Description |
|---|---|
Incremental Data Write Conflict Resolution Rule | IGNORE: Ignore conflicts (skip writing), REPLACE: Replace the entire row in case of conflicts. |
Handling of Zero Value for Time | Allow setting zero value for time to different data types to prevent errors when writing to the Target. |
Limits
| Limit | Description |
|---|---|
Oplog Size and Retention Settings | By default, the value of replication.oplogSizeMB or storage.oplogMinRetentionHours in MongoDB is too small. If data synchronization latency is significant, unconsumed oplogs may be removed. In this case, it is necessary to increase these parameters. |
Parameter Configuration for MongoDB Master-Slave Architecture | For MongoDB master-slave architecture, set the Source parameter oplogCollection to oplog.$main. |
ChangeStream Mode | MongoDB 3.6 and above support changeStream for capturing incremental data changes. Set the Source parameter captureMode to CHANGE_STREAM. For sharded clusters, use the MongoDB connection string for synchronization. |
Oplog Mode | When using oplog mode for data synchronization from a MongoDB instance, ensure the access to the local database. |
Character Set | Support utf8, utf8mb4, latin1. Other encodings have not been tested. |
Parameters
| Parameter | Description |
|---|---|
captureMode | Configure the MongoDB incremental data sync mode, supporting OP_LOG and CHANGE_STREAM modes. |
changeStreamBatchSize | Set the maximum number of change events per batch for MongoDB Change Stream. |
oplogCollection | Specify the collection name for MongoDB oplog. The default name is oplog.rs. |
timezone | Source time zone (the default time zone is UTC). |
Tips: To modify the general parameters, see General Parameters and Functions.
Prerequisites
| Prerequisite | Description |
|---|---|
Permissions for Account | A privileged account or a normal account with read and write permissions of PolarDbMySQL. |
Port Preparation | Allow the migration and sync node (Worker) to connect to the PolarDbMySQL port (e.g., 3306). |
Parameters
| Parameter | Description |
|---|---|
keyConflictStrategy | Strategy for handling primary key conflicts during write in Incremental DataTask:
|
dstWholeReplace | Convert INSERT and UPDATE operations into full row replacement in the Target. |
mergeMaxInsertSize | When the parallel strategy mergeMaxInsertSize is set to TABLE_IMPORT_OPTIMIZE, it defines the maximum number of rows to merge per batch for the same table (improve parallelism). |
Tips: To modify the general parameters, see General Parameters and Functions.