What is the option that can be used in PostgreSQL to make transactions see rows affected in previous parts of the transaction?

 The SQL standard is defined by four levels of transaction isolation basically regarding three phenomena. The three phenomenon must be prevented between concurrent transactions. The unwanted phenomena are:

• Phantom read: A transaction that re-executes a query, returning a set of rows that satisfy a search condition and then finds that the set of rows that have been satisfying the condition has changed due to another recently-committed transaction.
• Non-repeatable read: A transaction that re-reads the data that it has previously read and then finds that data has already been modified by another transaction (that committed since the initial read).
• Dirty read : A transaction when reads data that is written by a concurrent uncommitted transaction is the dirty read.