Subject Re: [firebird-support] FB 2.0.1, XNET protocol and Events
Author Helen Borrie
At 02:28 AM 25/07/2007, you wrote:
> > I have posted some days ago, that I have the problem, that the FB Server
> > shuts down every few minutes (Thread: FB Server shuts down every few
> > Minutes). Dmitry Yemanov told me, that possibly a badly written UDF is
> > the reason. I have done some tests and the reason is not a udf, but it
> > seems, that the combination of the XNET protocol and Events causes the
> > FB Server to shut down. I use a IBO feature called DML Caching and this
> > feature works with Events.
> What this feature do ? Just cache statement handles or something else ?
>If it is about statement handles - how it relate to events ?

It is an optional feature: it's enough to know that it uses
events. What happens when it is enabled is that a committed DML will
update and commit a cache table entry, causing a trigger to fire a
post_event off to all of the clients that are listening for it. A
listening client can then discover that a row that it has in its
buffer has changed by another transaction and, typically, it will
respond by invalidating that row in its buffer. Then, next time the
application touches that row, it will re-fetch it from the server.

I wonder what version of IBO Guido is using with Fb 2.0.1. To be a
valid test it would need to be 4.7 Build 16 or higher and also to
ensure that the Fb 2.0.1 fbclient.dll is used.

> > When I connect to the database via the XNET
> > protocol and try to register the Event the FB server crashes. It's
> > reproducible.
> Is it reproducible with IBX ? WIth IBO without DML Caching ?

IBX doesn't have this feature. And no, if DML Caching isn't enabled
in IBO, it obviously won't be reproducible.