Subject Re: Urgent help needed: application locks with > 1 user
Author ione1608
--- In, Helen Borrie <helebor@...>
> At 05:05 PM 23/10/2006, you wrote:
> >I have the following problem:
> >
> >I made an application which uses a FireBird database. The database
> >(SuperServer 1.5) runs on a pc. I have two clients connecting to
> >this database. Both clients use the same database user (which I
> >setup in the ODBC Administrator).
> >I thougt I was finished developing and began testing the
> >application. What happens is this:
> >Client 1 opens a window on which data is shown. When I open the
> >window on client 2 with another record, the window doesn't show
> >data. It looks like it's waiting. Even when I close the window on
> >client 1, client 2 is still 'waiting'. Only when I quit the
> >application on client 1, client 2 suddenly shows the data.
> >I'm quite a newbie with FireBird. I tried searching for the
> >but 'didn't find the solution or a post in which the same problem
> >discussed.
> >Is this what they call a deadlock?
> No. Deadlocks (and other lock conflicts) occur when two
> attempt to update (or delete) the same record. You will get an
> exception message telling you what kind of conflict it is.
> >The query I use is just a select (with noting about locks in it).
> >
> >Is this problem known?
> Are you getting any exception messages at all?

No I don't get any message. The second client just wait (not

> If you really are not updating or deleting anything, look at the
> isolation level of your transaction. If it is Consistency (a.k.a.
> SNAPSHOT TABLE STABILITY), then this is an exclusive, table-wide
> isolation level for a read/write transaction and is rarely if ever
> used. What you want is either concurrency (a.k.a. SNAPSHOT) or
> Committed. Neither of those will block each other when reading.

How can I find out the isolation level of the transaction?

> You might also ask on the firebird-odbc-devel list whether your
> configuration is right for what you want to do.
> If you wish to do that, and/or to continue this thread here, then
> need to provide more information than you have so far. For
> provide the connection string that the client application is using
> and say whether both clients are on separate machines to the one
> where the server is running.

I tried it with a server running on a pc. On this pc I was running a
VMware installation (virtual a different system). And another pc.
So two fysical pc's, and 1 virtual.

I will look to that list. I didn't know the existence of it. Thanks
for pointing it out!

> ./heLen