Note
For V4.4.x, this parameter is available starting with V4.4.1.
Description
approx_count_distinct_precision specifies the precision of the result of the approx_count_distinct function.
Privilege requirements
Query the parameter
sysand all user tenants can query this parameter by using theSHOW PARAMETERSstatement or theGV$OB_PARAMETERSview.Modify the parameter
sysand user tenants can modify this parameter.
Attributes
| Attribute | Description |
|---|---|
| Type | Integer |
| Default value | 10 |
| Value range | [4, 16] |
| Modifiable | Yes. You can use the ALTER SYSTEM SET statement to modify the parameter. |
| Effective upon OBServer node restart | No. |
Examples
Run the following command to set the precision of the cardinality estimation function to 10.
obclient> ALTER SYSTEM SET approx_count_distinct_precision = 10;