Before You Start
Constraints
- MgC cannot migrate data of the DATETIME type from MaxCompute. Before the migration, you need to convert such data to the STRING format.
- MgC cannot migrate data of the VARCHAR or CHAR type from MaxCompute. Before the migration, you need to convert such data to the STRING format.
- MgC cannot migrate metadata of transaction tables (those with the transactional=true field in DDL statements).
- The TIMESTAMP_NTZ type of data in MaxCompute is not supported by the Alibaba Cloud SDK. As a result, the metadata of involved tables will fail to be migrated.
- When partition data is migrated repeatedly, if the error message "Do not support update partition SerDeInfo for DLI table" is displayed, you need to manually delete the partition data from DLI and then migrate the data again.
- MgC allows you to narrow the migration scope to specific partitions in MaxCompute. You must enter the names of involved tables in the Excel template in lowercase letters. MaxCompute converts table names to lowercase during table creation. If the table names in the Excel template are in uppercase, the migration will fail as the tables cannot be recognized.
Notes
- Editing a CSV template file
When your use the CSV template provided by MgC to filter data, do not use Excel to edit the CSV file. The file edited and saved in Excel cannot be identified by MgC.
- Selecting a DLI connection
Migrating metadata and data requires different DLI connections. Migrating metadata requires a DLI connection with a SQL queue configured, while migrating data requires a DLI connection with a general-purpose queue configured. If an incorrect connection is configured for a migration task, the migration task will fail.
- Considering the constraint on the number of databases
During a metadata migration, MgC automatically creates a corresponding number of databases as listed in the metadata. Since the system has a quota of 10 DLI databases per account, exceeding this quota could cause the migration to fail.
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