This topic describes the limits of the EMR Serverless StarRocks service.
Billing methods
Both subscription and pay-as-you-go billing methods are supported.
Naming conventions
The following rules apply to instance, database, table, view, column, partition, username, and role names.
Allowed characters and length
| Object | Allowed characters | Max length | Start character |
|---|---|---|---|
| Instance, database, table, view, partition, role | Digits (0–9), letters (a–z, A–Z), underscores (_) | 64 characters | Letter |
| Column | Digits (0–9), letters (a–z, A–Z), underscores (_) | 1,023 characters | Letter or underscore (_) |
| Username | Digits (0–9), letters (a–z, A–Z), underscores (_); or digits only | 64 characters | Not specified |
Case sensitivity
| Object | Case sensitivity |
|---|---|
| Database name | Case-sensitive |
| Table name | Case-sensitive |
| View name | Case-sensitive |
| Column name | Case-insensitive |
Other constraints
Column names cannot be modified after creation.
Label names
When you import data, you can specify a label for the task. The following rules apply to label names:
| Attribute | Rule |
|---|---|
| Max length | 128 characters |
| Allowed characters | Digits (0–9), letters (a–z, A–Z), underscores (_) |
| Start character | Letter, digit, or underscore (_) |
Data type constraints
| Constraint | Detail |
|---|---|
| Key column types | FLOAT and DOUBLE are not allowed. Use DECIMAL for decimal values. |
| VARCHAR length | 1–1,048,576 bytes |
Encoding
StarRocks supports only UTF-8 encoding. Other encoding methods, such as GB, are not supported.
Subquery limit
By default, a query can contain a maximum of 10,000 subqueries.
Core parameter constraints
Warning
Do not change the following parameters from their default values. Doing so voids the product guarantee for your instance and can cause critical failures or data loss.
| Parameter | Description | Default value | Applicable version | Impact if changed |
|---|---|---|---|---|
replication_num | Number of replicas | 3 | Coupled compute and storage | Setting to 1 or 2 risks data loss and may cause computing skew and node breakdowns. |
enable_persistent_index | Enable primary key index persistence | true | All versions | Setting to false stores the primary key index in memory only, which can lead to data loss, data duplication, and node breakdowns. |
persistent_index_type | Persistence index type | CLOUD_NATIVE | Decoupled compute and storage | Setting to LOCAL may cause uncontrolled disk space usage, making the instance unusable. |