Note
This parameter is available starting with V4.1.0.
Description
dump_data_dictionary_to_log_interval specifies the interval for persistent data dictionary dumps.
Privilege requirements
Query the parameter
You can query this parameter in the
systenant or a user tenant by executing theSHOW PARAMETERSstatement or querying theGV$OB_PARAMETERSview.Modify the parameter
You can modify this parameter in the
systenant or a user tenant.
Attributes
Note
After you upgrade from a previous version to V4.4.1, the value of this parameter remains the same as that in the previous version.
| Attribute | Description |
|---|---|
| Parameter type | Time |
| Default value | 0 (unit: second)
NoteAs of V4.4.1, the default value is changed from 24H to 0. If this parameter is set to 0, the data dictionary will not be dumped according to this parameter. To stop the data dictionary dump, you need to execute the |
| Value range | [0s, +∞)
NoteAs of V4.4.1, the value range of this parameter is changed from (0s, +∞) to [0s, +∞). |
| 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
The data dictionary serves only user tenants and is persisted to the system log stream (SYS_LS) of a user tenant through PALF. When a user tenant is created, the data dictionary service is automatically activated and runs on the LEADER replica of the SYS_LS log stream of the user tenant.
When log archiving is enabled, an asynchronous data dictionary dump task is automatically triggered. OceanBase Database supports scheduling regular data dictionary dumps using the tenant-level parameter dump_data_dictionary_to_log_interval and the DBMS_DATA_DICT package (introduced in V4.4.1). We recommend that you use the DBMS_DATA_DICT package to schedule data dictionary dumps.
Starting from OceanBase Database V4.2.0, you can query the CDB_OB_DATA_DICTIONARY_IN_LOG view in the sys tenant or the DBA_OB_DATA_DICTIONARY_IN_LOG view in a user tenant to obtain the dictionary locations.
Examples
Set the interval for persistent data dictionary dumps to 24H.
obclient> ALTER SYSTEM SET dump_data_dictionary_to_log_interval = '24H';
References
For more information about the data dictionary, see Overview of CDC.
For more information about log archiving, see Log archiving.