This topic describes the general naming conventions for OceanBase Database objects.
During database development, database objects should be named in a standardized manner to make code more readable and easier to understand and inherit. This topic provides developers with recommendations on database object naming conventions.
General conventions
The following sections describe the general conventions and precautions for naming objects.
Use consistent character sets for databases and tables, and use consistent character sets for all tables. We recommend that you use the UTF8MB4 character set for all. We do not recommend that you use custom character sets at the table level.
Use unified and standardized naming conventions.
Use full English words.
Use standard abbreviations.
Do not use Chinese characters.
Do not use both Pinyin and English in the same object name.
Do not use meaningless strings consisting purely of digits, meaningless letters, underscores (_), or special characters.
Do not use spaces between the characters in an object name.
Do not use system reserved words and keywords.
Do not use object names that conflict with database systems or common access methods.
Do not use pure Pinyin in an object name.
Identifier length limits
MySQL mode
Item Maximum length Cluster name 128 bytes Tenant name 64 bytes Username 64 bytes Database name 128 bytes Table name 64 bytes Column name 128 bytes Index name 64 bytes View name 64 bytes Alias 255 bytes Table group name 128 bytes The name of the partition. 64 characters Oracle mode
Type Maximum length Cluster name 128 bytes Tenant name 64 bytes Username 64 bytes Table name 128 bytes Column name 128 bytes Index name 128 bytes View name 128 bytes Alias 255 bytes The name of the object. 128 bytes Table group name 128 bytes The name of the partition. 64 characters
Maximum OBProxy connections
| Type | Upper limit |
|---|---|
| Number of connections per OBProxy | You can specify the client_max_connections parameter of an OBProxy to specify the maximum number of connections of the OBProxy. The default value is 8192. Note You can increase the number of OBProxy nodes or the value of the client_max_connections parameter to increase the maximum number of connections for a cluster. |
Maximum number of partition replicas
| Type | Upper limit |
|---|---|
| Number of partition replicas per OBServer | 500,000 Note We recommend that you do not set the number of partition replicas per OBServer to a value greater than 100,000. |
Single-table limits
| Type | Upper limit |
|---|---|
| Row length | 1.5 MB |
| Number of columns | 4,096 |
| Number of indexes | 128 |
| Total number of index columns | 512 |
| Index length | 1.5 MB |
| Total number of primary key columns | 64 |
| Primary key length | 16 KB |
| Number of partitions |
|
String type limits
MySQL mode
Type Maximum length CHAR255 bytes VARCHAR65,535 bytes BINARY255 bytes VARBINARY65,535 bytes BLOB65,535 bytes TEXT65,535 bytes Oracle mode
Type Maximum length CHAR2,000 bytes VARCHAR32,767 bytes VARCHAR232,767 bytes NCHAR2,000 bytes NVARCHAR232,767 bytes