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Oracle is different in this respect than SQL-Server and other databases. There is no lock escalation in Oracle. This concept does not exist in Oracle - as a billion row locks have the same overheads as a single row lock. None.
Read consistency also differs. Dirty reads do not exist.
A reader of data can never block a writer of data. And vice versa - a writer of data can never block a reader of data. Oracle implements a concept known as multi-version concurrency control. Different versions of data can exist simultaneously.
For example, you open a SQL cursor "+select * from some_table+". There are a 1000 rows. You have fetched a 100 rows. I delete the entire table and commit. I've created a new version of the truth. Your process however still will fetch 900 rows as a 1000 rows where the truth at the time you have created that read consistent SQL cursor.
There are fundamental concepts that differ between Oracle and most other databases. Concepts that makes Oracle the most advanced database product on this planet, and the reason for its success in the market place.
Not understanding these concepts will be a fundamental mistake on your part.
Oracle RAC adds a bunch of new concepts and features too. Do not underestimate its complexity - and ability to out perform and out scale any other similar RDBMS product in the world.