Rollback Parameters

max_undo_workers

Parameter description: Specifies the number of undo worker threads invoked during asynchronous rollback. The parameter setting takes effect after the system is restarted.

This parameter is a SIGHUP parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: an integer ranging from 1 to 100

Default value: 5

undo_space_limit_size

Parameter description: Specifies the threshold for forcibly recycling undo space. When the undo space usage reaches 80% of the threshold, forcible recycling starts. You can set this parameter to a large value based on service requirements and then set it to a proper value based on the actual undo space usage.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: an integer ranging from 800 MB to 32 TB

Default value: 256 GB

undo_limit_size_per_transaction

Parameter description: Specifies the undo space threshold of a single transaction. If the threshold is reached, the transaction is rolled back due to an error.

This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: an integer ranging from 100 MB to 32 TB

Default value: 32 GB