Constraints

To improve the stability and security of HTAP instances, note the following constraints:

1. SQL statements are case-sensitive.
2. A primary key must be defined for a table during synchronization, or synchronization is skipped.
3. You need to select proper partition keys. If the number of partitions is greater than 2 but does not exceed 20, the RANGE partitions created in GaussDB(for MySQL) DB instance will be automatically synchronized to HTAP instances. Other partitions will not be synchronized. You can re-specify partition keys during synchronization task creation.
4. You need to properly define sorting keys and sort the query results based on the query frequency and left matching. When there are different sorting requirements, you can create materialized views.
5. Some DDL statements executed on GaussDB(for MySQL) DB instances cannot be synchronized to HTAP instances, which may cause synchronization failures or data inconsistencies. For details, see Introducing DDLs that Cannot Be Synchronized.
6. HTAP instances use snapshots to accelerate query. Currently, projection-based query is not supported.
7. You can only insert base tables for materialized views. You cannot modify and delete data in materialized views. Materialized views cannot be created in synchronized databases. They can be created only in self-created databases.
8. Databases created during data synchronization cannot be modified. You can only modify the databases that you created on the HTAP instances.
9. The names of the databases and tables to be synchronized cannot contain Chinese characters.