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 suggestions 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 characters Column name 128 bytes Index name 64 bytes View name 64 bytes Alias 255 bytes Partition name 64 bytes 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 Object name 128 bytes Partition name 64 bytes
Maximum number of ODP connections
| Type | Upper limit |
|---|---|
| Number of connections per ODP | You can specify the client_max_connections parameter of an ODP to specify the maximum number of connections of the ODP. The default value is 8192.
Note |
Maximum number of partition replicas
| Type | Upper limit |
|---|---|
| Number of partition replicas per OBServer node | No upper limit.
Note |
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 |
|
Single-column limits
| Type | Upper limit |
|---|---|
| Length of an index column | 262,143 bytes |
String type limits
MySQL mode
Type Maximum length CHAR256 bytes VARCHAR1,048,576 bytes BINARY256 bytes VARBINARY1,048,576 bytes BLOB536,870,911 bytes TEXT536,870,911 bytes Oracle mode
Type Maximum length CHAR2,000 bytes VARCHAR32,767 bytes VARCHAR232,767 bytes NCHAR2,000 bytes NVARCHAR232,767 bytes