[rdf4j-dev] Question about READ_UNCOMMITTED

[Håvard Ottestad <hmottestad@xxxxxxxxx>]

Hi,

There is a test in RepositoryConnectionTest called testEmptyCommit(). This test seems to do the following:

 - Create two connections
 - Add data to one of the connections
 - Make sure the other connection doesn’t see said data

This test is being run at READ_UNCOMMITTED isolation level. I’m wondering then if the definition of READ_UNCOMMITTED is correct.

The current definition is: 
/**
 * Read Uncommitted: transactions can be rolled back, but not necessarily isolated: concurrent
 * transactions might see each other's uncommitted data (so-called 'dirty reads')
 */

From the test I wonder if READ_UNCOMMITTED is actually meant to be a snapshot isolation against other transactions adding data after a READ_UNCOMMITTED connection has opened? So you can do dirty reads, but only from writes that happened before the connection was opened.

Håvard