collect
The time at which ApsaraDB RDS collects the statistics of the new instance.
Before: ApsaraDB RDS collects the statistics of the new instance before the switchover to ensure service stability. If the original instance contains a large amount of data, the upgrade may require a long period of time.
After: ApsaraDB RDS collects the statistics of the new instance after the switchover to accelerate the upgrade. If you access tables for which no statistics are generated, the query plans that you specify may be inaccurately executed. In addition, your database service may be unavailable during peak hours.