Note
- For V4.2.x, this parameter is available starting with V4.2.0.
- For V3.x, this parameter is available starting with V3.1.5.
Description
In Shared-Nothing (SN) mode, the
datafile_maxsizeparameter specifies the maximum size to which a disk file can be automatically expanded.In Shared-Storage (SS) mode, the value of the
datafile_maxsizeparameter is meaningless and can be modified, but the modification will not take effect.
Privilege requirements
Query the parameter
The
systenant and all user tenants can use theSHOW PARAMETERSstatement or theGV$OB_PARAMETERSview to query this parameter.Modify the parameter
Only the
systenant can modify this parameter. User tenants cannot modify this parameter.
Attributes
| Attribute | Description |
|---|---|
| Type | Capacity |
| Default value | 0 |
| Value range | [0M, +∞) |
| Modifiable | Yes. You can use the ALTER SYSTEM SET statement to modify the parameter. |
| Effective upon OBServer node restart | No. The setting takes effect immediately. |
Considerations
In SN mode, the default value of datafile_maxsize is 0, indicating that disk file auto-expansion is disabled. If you want to enable auto-expansion, set datafile_maxsize to a non-zero value:
The value of
datafile_maxsizemust be greater than the current disk space occupied by the data file (datafile_sizeordatafile_disk_percentage). If the set value is smaller than the current disk space occupied by the data file, auto-expansion will not be triggered.If the value of
datafile_maxsizeexceeds the maximum available disk space, the actual available disk space will be used as the maximum value.
Examples
In SN mode, set the maximum size to which a disk file can be automatically expanded to 10G.
obclient> ALTER SYSTEM SET datafile_maxsize = '10G';