Isolation levels in oracle [closed] Isolation levels in oracle [closed] database database

Isolation levels in oracle [closed]


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.


There are four isolation levels

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