isolation levels exists in spring or hibernate

Question

I would like to know Why do isolation levels exists in spring or hibernate if these are concepts of database? Aren't those handled by database so that we need to explicitly specify them in the spring application? what is the reason behind it?

Answer 1

Transactions isolation levels are set per connection. They can even be defined per a particular transaction. But someone who starts the transaction needs to specify the isolation level.

In case of JDBC it would be: Connection#setTransactionIsolation(). In your case this someone is Hibernate or Spring.