Some major limitations due to which partial data loss or structural disparity can happen are listed below.
- Columns with the following data types will not be migrated.
- GEOMETRY
- POINT
- MULTIPOINT
- LINESTRING
- MULTILINESTRING
- POLYGON
- MULTIPOLYGON
- GEOMETRYCOLLECTION
- For tables having the below-mentioned data types and no primary key, only staging migration can be done, cdc (live-migration) is not possible.
- LONGBLOB
- MEDIUMBLOB
- JSON
- LONGTEXT
- MEDIUMTEXT
- For CDC (Change Data Capture), CREATE TABLE, DROP TABLE, RENAME TABLE, ADD COLUMN, DROP COLUMN, changing the column data type, and renaming a column are supported. However, updates made to other attributes, such as column default value, column nullability, character set, and so on, are not supported.
- CDC isn't supported for sources hosted on Amazon RDS MySQL 5.5 or lower.
- Temporal data tables or system-versioned tables are not supported on MariaDB source and target databases.
Note: The migration of secondary schema (foreign key, check constraints, unique constraints, indexes) might fail if the underlying column(s) aren’t migrated (or partially migrated) by DMS.