Data Sync

Last updated: 2020-12-29 14:27:16

    Task Verification Failure

    Possible causes:

    • The account or password of the target instance is incorrect.
    • The network is disconnected; for example, the firewall or security group blocks the egress IP of the sync tool, and cross-network access is not supported currently.
    • The target instance does not exist.

    Solution: check the above causes and make adjustments accordingly.

    Long Delay of Sync Task

    Possible causes:

    • The transaction on the source instance is large. Data sync is to sync data from the replica. As the timestamp of each transaction in a binlog is the start time of the transaction, if there is a large transaction, the reported timestamp for data sync will still be the start time of the transaction even in concurrent sync.
    • There is a delay on the replica; for example, DDL replay attacks or read-only accounts cause high pressure and delay on the replica, leading to database sync delay.

    Solution: check whether there are large transactions or batch processing operations. If the delay persists after a period of time, please contact us for troubleshooting.

    Extra Data After Data Sync

    Possible causes: write lock is not enabled for the target instance and some additional data is written to it; the corresponding table may lack a primary key; therefore, when the sync tool sends a request again, part of the data will be written to the target instance again.

    Solution: add a primary key to the source table, delete existing data from the target table, and sync the data again. Or, you can manually delete extra data from the target table.

    Writable Target Database

    Data sync does not lock the target database, which can still be read from/written to normally. Therefore, please manipulate the target database with caution.

    DDL Replay Failure

    Possible causes: the source and target databases are on different versions, leading to differences in DDL syntax.

    Solution: manually run the DDL statements again in the target database.

    Database Sync Failure with Missing or No Data in the Corresponding Table

    Possible causes: the account required by sync or the table structure of the target database is modified.

    Solution: pause the sync task, modify the corresponding account, change the table structures of the target and source databases to the same, and perform sync again.