Flashback
This section describes parameters related to the flashback function. In V100R002C10, only the Ustore engine supports flashback, while the Astore engine does not support flashback.
enable_recyclebin
Parameter description: Specifies whether the recycle bin is enabled or disabled in real time.
This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.
Value range: Boolean
Default value: off
Caution: The recycle bin does not support Astore and supports only Ustore.
recyclebin_retention_time
Parameter description: Specifies the retention period of objects in the recycle bin. The objects will be automatically deleted after the retention period expires.
This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.
Value range: an integer ranging from 1 to 2147483647. The unit is s.
Default value: 15 min (900s)
version_retention_age
Parameter description: Specifies the number of transactions retained in the old version. If the number of transactions exceeds the value of this parameter, the old version will be recycled and cleared.
This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.
Value range: an integer ranging from 0 to 576460752303423487. 0 means no delay.
Default value: 0
CAUTION: This parameter has been deprecated.
vacuum_defer_cleanup_age
Parameter description: Specifies the number of transactions by which VACUUM will defer the cleanup of invalid row-store table records, so that VACUUM and VACUUM FULL do not clean up deleted tuples immediately. You can also set this parameter to configure the retention period of the flashback function in the old version.
This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.
Value range: an integer ranging from 0 to 1000000. 0 means no delay. The value range needs to be extended to 100 million.
Default value: 0
undo_retention_time
Parameter description: Specifies the period for retaining undo logs of earlier versions.
This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1.
Value range: an integer ranging from 0 to 2147483647. The unit is second.
Default value: 0