Yes it differs between different database vendors. Postgres supports starting a transaction with configuring transaction isolation levels and characteristics https://www.postgresql.org/docs/current/sql-start-transaction.html. MySQL supports starting a transaction with configuring only transaction characteristics(but additionally WITH CONSISTENT SNAPSHOT) https://dev.mysql.com/doc/refman/8.0/en/commit.html MS SQL Server does not support such kind of configuration syntax to start a transaction. https://docs.microsoft.com/en-us/sql/t-sql/language-elements/begin-transaction-transact-sql?view=sql-server-ver15 I'm thinking we might provide an API which seems like this ``` SqlConnection#begin(Supplier<String> startTxSql, Handler<AsyncResult< Transaction>> handler); ``` so that users could be able to decide how the transactions are started.