Illustration strms049.gif shows messages being enqueued and browsed within a database. Two sessions are enqueuing messages in the following sequence:

1. Session 1 enqueues message e1 as part of transaction T1.

2. Session 2 enqueues message e2 as part of transaction T2.

3. Session 1 enqueues message e3 as part of transaction T1.

4. Session 2 commits transaction T2.

5. Session 1 commits transaction T1.

Session 3 browses messages in the queue at two different times. The first time session 3 browses messages, session 2 has committed, but session 1 has not yet committed. For this browse, the browse set shows messages in the following order:

1. e2

2. e1

3. e3

The second time session 3 browses messages, both session 1 and session 2 have committed. For this browse, the browse set shows messages in the following order:

1. e1

2. e3

3. e2