[mythtv-users] Help, database corrupted after connecting with a newer frontend

[myth at ultratux.org]

On Saturday 02 April 2005 22:16, Donavan Stanley wrote:
> On Apr 2, 2005 3:07 PM, myth at ultratux.org <myth at ultratux.org> wrote:
> > I -stupidly in hindsight- connected to my mythtv backend version 0.14
> > with a frontend 0.16.  It didn't work, it  complained about different
> > versions.
>
> Would have been stupidly in foresight with a little homework...

Yeah...  You know how it is though...

> > Alas, to my amazement that single act fucked up the backend database.
>
> The term you are looking for is "upgraded" not fucked up.  New
> versions often call for database changes, so the database structure
> gets changed.  Nothing is gone, it's just in a different layout than
> what your .14 backend wants it in.

Yes I know that. I called it fscked-up because nothing works with my current 
backend. I did not expect a frontend to do a DB update. Clients do not 
usually DO that, you know. 

> > Is there a way to repair this? A rollback script? A howto do it manually?
>
> Restore your database from a backup or start running a .16 backend.

As I mentioned a restore is not feasible as I would lose 3 months worth of 
programs easily equal to (or greater than) some 300 gigabytes of shows.

But I already started compiling 0.17 on my backend before you answered, I hope 
it will compile and run fine without too many tricks & hacks.

> > (I'm not even daring to touch the subject of how in H*LL this can
> > happen... Either the backend disallows access to the incompatible
> > frontend, or it works with it, but corrupting it ?!? That's really bad.
> > Losing everything just by booting a different frontend, for gods sake...)
>
> It has nothing to do with backend vs frontend and everything to do
> with database schema versions between releases.   You can't run in a
> mixed enviroment it's been repeated often on the mailing lists.

Uh-huh.  However, it would seem prudent if some care had been taken in the 
code so that only a BACKend would upgrade the DB, not some loose random 
frontend that happens to connect. This is a major denial-of-service 
vulnerability now.  
(And apart from the ML, it should be in the docs too)

/* oops, we encounter a legacy database scheme... */ 
if $0 = "mythbackend" do 
	$(upgrade_database)
else
	echo "I don't support this database scheme AND I'M JUST A FRONTEND. Exiting."
	exit -255
fi

You get the point...

Greetings,
Mart