What Is a READ WRITE Transaction?

A READ WRITE transaction is a transaction in which the read consistency is set at the statement
level. In a READ WRITE transaction, a logical snapshot of the database is created at the
beginning of the execution of each statement and released at the end of the execution. This
guaranties that all reads within a single statement get consistent data from the database.
For example, if you have a query statement that takes 10 minutes to be executed, a snapshot of
the database will be created for this statement for 10 minutes. If a subquery is used in this
statement, it will get the consistent data no matter when it gets executed within this 10 minutes. In
another word, data changes made during this 10 minutes by other users will not impact the
execution of this query statement.
By default, all transactions are started as READ WRITE transactions.