Note
This parameter is available starting with V4.1.0.
Description
dump_data_dictionary_to_log_interval specifies the interval for persisting the data dictionaries of all users.
Privilege requirements
Query the parameter
sysand all user tenants can query the value of this parameter by using theSHOW PARAMETERSstatement or theGV$OB_PARAMETERSview.Modify the parameter
Both the
systenant and the user tenant can modify this parameter.
Attributes
Notice
In V4.4.1, this parameter is set to the value in the low version before the upgrade.
| Attribute | Description |
|---|---|
| Type | Time |
| Default value | 0, in seconds.
NoteStarting from V4.4.1, the default value changed from 24 hours to 0. If this parameter is set to 0, no dictionary data is generated. To stop generating dictionary data, execute the |
| Value range | [0s, +∞)
NoteStarting from V4.4.1, the value range is adjusted 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 service is only provided for user tenants and is persisted in the system log stream (SYS_LS) of a normal tenant using PALF. After a user tenant is created, the data dictionary service is automatically started and runs on the leader replica of the user tenant's SYS_LS log stream.
When log archiving is enabled, an asynchronous data dictionary generation task is automatically triggered. OceanBase Database supports scheduling data dictionary generation tasks using the tenant-level parameter dump_data_dictionary_to_log_interval or the DBMS_DATA_DICT package (available since V4.4.1). We recommend using the DBMS_DATA_DICT package to schedule data dictionary generation.
Starting from OceanBase Database V4.2.0, you can record data dictionary generation logs in the DBA or CDB views. You can query the CDB_OB_DATA_DICTIONARY_IN_LOG view in the sys tenant to obtain the dictionary location information, or query the DBA_OB_DATA_DICTIONARY_IN_LOG view in a non-sys tenant to obtain the dictionary location information.
Examples
You can set the persistence cycle of tenant data dictionaries to 24H.
obclient> ALTER SYSTEM SET dump_data_dictionary_to_log_interval = '24H';
References
For more information about data dictionaries, see Data dictionaries supported by OBCDC.
For more information about log archiving, see Log archiving.