In the following situations, even you have enabled the Async Commit feature and the one-phase commit feature using the system variables, TiDB will not use these features:
- If you have enabled TiDB Binlog, restricted by the implementation of TiDB Binlog, TiDB does not use the Async Commit or one-phase commit feature.
- TiDB uses the Async Commit or one-phase commit features only when no more than 256 key-value pairs are written in the transaction and the total size of keys is no more than 4 KB. This is because, for transactions with a large amount of data to write, using Async Commit cannot greatly improve the performance.