Isolation levels in oracle [closed]

Question

I would like to know different isolation levels with respect to commit, and would also like to know about row-level and table-level lock.

Answer 1

There are four isolation levels

1. Read uncommitted or Read Dirty Buffers
2. Read Committed or repeated reads
3. Phantom reads
4. Serializable

Answer 2

ANSI/ISO SQL defines four isolation levels:

• serializable
• repeatable read
• read committed
• read uncommitted

According to Oracle's Database Development Guide, chapter 6.6.1: Transaction Interaction and Isolation Level, you can request either isolation level READ COMMITTED (the default) or SERIALIZABLE.

Please note, however, that what Oracle call SERIALIZABLE is actually snapshot isolation.

For more information about row-level and table-level locks, see Overview of the Oracle Database Locking Mechanism and Locking tables explicitly.