Note
This parameter was introduced in OceanBase Database V1.4.
Description
freeze_trigger_percentage specifies the threshold of MemStore memory used by tenants for triggering a freeze.
Attributes
| Attribute | Description |
|---|---|
| Type | Integer |
| Default value | 20
NoteThe default value is changed from |
| Value range | (0, 100) |
| Modifiable | Yes. You can use the ALTER SYSTEM SET statement to modify the parameter. |
| Effective upon OBServer node restart | No |
Considerations
You can specify the following parameters to adjust the percentage of MemStore in the memory for a tenant:
When the usage of the active MemStore of a tenant reaches the limit specified by
freeze_trigger_percentage×memstore_limit, wherememstore_limit= tenant memory size ×memstore_limit_percentage, the system automatically triggers a freeze, which is the prerequisite step for a minor compaction, and then schedules a minor compaction. After the minor compaction is completed, the system releases the occupied MemStore memory.When the memory is insufficient, you can increase the value of the
memstore_limit_percentageparameter and lower the value of thefreeze_trigger_percentageparameter to temporarily expand the memory and promptly release the memory space. Thememstore_limit_percentageparameter specifies the percentage of tenant memory available for MemStore writes. The default value0indicates that this percentage is adaptively adjusted by the system.
Examples
obclient> ALTER SYSTEM SET freeze_trigger_percentage=20;