When “assert=durable_timestamp” is configured for a table, committing a prepared transaction will check for each update U’ in the transaction with previous version U that  U’.commit_timestamp > U.durable_timestamp. This assertion to be used for checkpoint durable tables. This assertion will ensure that the versions of updates will become durable in the same order as oldest to newest version. If durable timestamp is managed in monotonically increasing order across the system, this assertion can be disabled to improve the performance.