Question

i have a question about data visibility in database views.
I use Oracle.
I have a table myscheme.users and a table global.users (myscheme and global are schemes)
There is a view “globalusers” in the global scheme which merges both user tables.

I have a java application that inserts a new user in the myscheme.users table. After that it makes a query for the new user in the globalusers-view to load the newly created user.
As all this happens inside the same transaction. My question is now, why is the newly created user visible in the myscheme.user table but not in the globalusers-view?
When the transaction has been closed, the user is also in the globaluser-view.

My application is running inside a JBoss 5 using hibernate.

The view is defined in that way:

CREATE OR REPLACE VIEW V_USERACCOUNT AS
    SELECT u.USERACCOUNT_ID,u.USERNAME,u.INITIALS,u.COMMONNAME,u.PASSWORD,'local' AS source
        FROM "USERACCOUNT" u
    UNION
        SELECT u1.USERACCOUNT_ID,u1.USERNAME,u1.INITIALS,u1.COMMONNAME,u1.PASSWORD 'global' AS source
        FROM GLOBAL."USERACCOUNT" u1

Answer 1

If the INSERT into the table and the SELECT from the view are, in fact, part of the same database transaction (which necessarily implies that they are executed in the same database session), the newly inserted row would be visible in the view (assuming the row meets whatever criteria the view uses to determine which rows to display). If the new user is not in the view, that implies that either

1. The INSERT and the SELECT are not part of the same database transaction, or
2. The INSERT is not sufficient to cause the row to be available in the view. Perhaps there is some other lookup table that is joined in the view that doesn’t have the data for the new row when you query the view but the lookup is populated later in the transaction.
3. You have a bug somewhere in your code where the INSERT isn’t actually happening when you think it is or the query isn’t happening after the INSERT or the query isn’t actually hitting the view you posted.

Based on your latest update, it appears that #1 is almost certainly the problem. If you have different DataSources, the INSERT uses one DataSource, and the SELECT uses a second DataSource, the two operations are not happening in the same database transaction. They may be happening in the same application server transaction– the application server may well be creating a distributed transaction– but if it’s not the same database transaction, you won’t be able to see uncommitted changes.