Machine specifications of a single OBServer node
The following table lists the machine specifications of a single OBServer node that guarantee stable cluster running:
Configuration |
Maximum requirement |
Minimum requirement |
|---|---|---|
| CPU | 512C | 4C |
| Memory | 1 TB | 16 GB |
Cluster name length
Item |
Maximum length |
|---|---|
| Cluster name | 128 bytes |
Identifier length
MySQL-compatible mode
Oracle-compatible mode
Item |
Maximum length |
|---|---|
| Username | 64 bytes |
| Tenant name | 63 bytes |
| Database name | 128 characters |
| Table name | 64 characters |
| Partition name | 64 characters |
| Column name | 128 characters |
| Index name | 64 characters |
| View name | 64 characters |
| Alias | 255 characters |
| Table group name | 127 bytes |
| User-defined variable | 64 characters |
Item |
Maximum length |
|---|---|
| Username | 64 bytes |
| Table name | 128 bytes |
| Column name | 128 bytes |
| Partition name | 64 bytes |
| Index name | 128 bytes |
| View name | 128 bytes |
| Alias | 128 bytes |
| Object name | 128 bytes |
| Table group name | 127 bytes |
Limit on the number of tenants that can be created on a single OBServer node
Type |
Maximum limit |
|---|---|
| Number of tenants that can be created on a single OBServer node | The number of tenants is affected by the cluster deployment architecture and hardware factors. The minimum memory supported by OceanBase Database for a tenant is 4 GB, and you can calculate the number of tenants based on 4 GB per tenant. |
ODP connections
Maximum number of connections
Item |
Upper limit |
|---|---|
| Number of connections per ODP | It is specified by the client_max_connections parameter of ODP. The default value is 8192.
NoteYou can increase the number of ODP nodes or the value of the |
Connection limit for a single OBServer node
Type |
Maximum limit |
|---|---|
| Number of connections to a single OBServer node | 256K |
Maximum number of partition replicas
Item |
Upper limit |
|---|---|
| Number of partition replicas per OBServer node | Unlimited.
NoteYou can estimate the number of partition replicas of each OBServer node based on the memory size of the tenant. 1 GB of memory supports about 20,000 tablets. |
Single table
Item |
Upper limit |
|---|---|
| Row length | 1.5 MB |
| Number of columns | 4,096 |
| Number of indexes | 128 |
| Total number of columns in a single index | 64 |
| Index length | 16 KB |
| Total number of primary key columns | 64 |
| Primary key length | 16 KB |
| Number of partitions |
|
| Maximum amount of data in a single table | In theory, OceanBase Database supports an unlimited amount of data. Based on best practices, 50 million rows are recommended in general scenarios. For wide tables with 100 to 200 fields, a maximum of about 10 million rows is recommended. |
Single column
Item |
Upper limit |
|---|---|
| Length of an index column | 16 KB |
String type
MySQL-compatible mode
Oracle-compatible mode
Item |
Maximum length |
|---|---|
CHAR |
256 characters |
VARCHAR |
262,144 characters |
BINARY |
256 bytes |
VARBINARY |
1,048,576 bytes |
TINYBLOB |
255 bytes |
BLOB |
65,535 bytes |
MEDIUMBLOB |
16,777,215 bytes |
LONGBLOB |
536,870,910 bytes |
TINYTEXT |
255 bytes |
TEXT |
65,535 bytes |
MEDIUMTEXT |
16,777,215 bytes |
LONGTEXT |
536,870,910 bytes |
Item |
Maximum length |
|---|---|
CHAR |
2,000 bytes |
NCHAR |
2,000 bytes |
VARCHAR |
32,767 bytes |
VARCHAR2 |
32,767 bytes |
NVARCHAR2 |
32,767 bytes |
BLOB |
536,870,910 bytes |
CLOB |
536,870,910 bytes |
Transaction size limit
In theory, OceanBase Database imposes no limit on the transaction size. The transaction size is limited only by the storage space.
Weak consistency read latency limit
The weak consistency read latency supported by OceanBase Database is controlled by the tenant-level configuration item max_stale_time_for_weak_consistency. The default value is 5s, and the latest data can be read with a minimum latency of 5s.
clog limits
Type |
Limit |
|---|---|
| Size of a single clog entry | 3.5 MB |
| Maximum network latency for clog synchronization | The maximum network latency for clog synchronization is 1s, but the one-way network latency between the arbitration server and OBServer nodes of the OceanBase cluster must be less than or equal to 800 ms. |
Feature usage
Physical standby databases
The following table describes the limitations on the physical standby database feature.
Item |
Description |
|---|---|
| Maximum number of standby tenants supported by one primary tenant | The number of standby tenants supported by a single primary tenant is unlimited at the product level. However, because standby tenant synchronization consumes the CPU, memory, I/O resources, and network bandwidth of the primary tenant, we recommend that you determine the number of standby tenants based on the resource usage of the source tenant and actual business requirements. |
| Whether homogeneous resources are required for the primary and standby tenants | Resources of the primary and standby tenants do not need to be homogeneous. We recommend that you use the same resource specifications for the primary and standby tenants. |
| Parameters | The parameters of the primary tenant are independent of those of a standby tenant, and parameter modifications are not physically synchronized. After you modify a parameter of the primary tenant, you must assess whether to modify the corresponding parameter of the standby tenants. |
| System variables | System variables of the primary and standby tenants are physically synchronized. If you modify a system variable of the primary tenant, the system synchronously modifies the corresponding system variable of the standby tenants. |
| Users and passwords | You can create users and change user passwords only in the primary tenant. The updated information is synchronized to the standby tenants. |
| Read and write operations | A standby tenant supports only read operations. |
| Minor and major compactions | Minor compactions in the primary tenant are independent of those in the standby tenants. Major compactions are not performed in a standby tenant. Instead, the major compaction information is synchronized from the primary tenant to the standby tenants. |
| Switchover | All replicas of log streams of the standby tenants must be online. |
| Failover | All replicas of log streams of the standby tenants must be online. |
| Optimizer statistics | A standby tenant does not collect statistics. The statistics of a standby tenant are synchronized from the primary tenant. |