Note
For V4.4.x, this parameter is available starting with V4.4.1.
Overview
approx_count_distinct_precision specifies the precision of the result returned by the approx_count_distinct function.
Privilege requirements
Query parameters
Both the
systenant and all user tenants can query this parameter using theSHOW PARAMETERSstatement or theGV$OB_PARAMETERSview.Modify parameters
Both the
systenant and user tenants can modify this parameter.
Attributes
Attribute |
Description |
|---|---|
| Parameter type | Integer |
| Default Value | 10 |
| Value range | [4,16] |
| Modifiable | Yes, you can use theALTER SYSTEM SETStatement modification. |
| Whether to restart the OBServer node for the change to take effect | No |
Configuration example
Run the following command to set the calculation precision of the cardinality estimation function to 10.
obclient> ALTER SYSTEM SET approx_count_distinct_precision = 10;