Sun GlassFish Enterprise Server v2.1.1 Performance Tuning Guide

Isolation Level Settings

Two settings control the connection pool’s transaction isolation level on the database server:

Avoid specifying Transaction Isolation Level. If that is not possible, consider setting Isolation Level Guaranteed to false and make sure applications do not programmatically alter the connections’ isolation level.

If you must specify isolation level, specify the best-performing level possible. The isolation levels listed from best performance to worst are:

  1. READ_UNCOMMITTED

  2. READ_COMMITTED

  3. REPEATABLE_READ

  4. SERIALIZABLE

Choose the isolation level that provides the best performance, yet still meets the concurrency and consistency needs of the application.