Re: What makes an OODBMS different from an RDBMS?
Date: Wed, 28 Nov 2001 12:41:14 -0000
Message-ID: <9u2lva$50v$1_at_pea.uk.research.att.com>
"Carl Rosenberger" <carl_at_db4o.com> wrote in message
news:9u2hot$6kk$05$1_at_news.t-online.com...
> However we do already write data in the right order:
> - Changed objects always get a new and free space in the database file
> - write the object first
> - switch the pointer afterwards
This sounds like a shadow-object algorithm, similar to shadow-paging but at an object level. By what method do you ensure that allocation of free space and the pointer update is atomic and durable?
Cheers,
Tim
> With this algorithm we already have an extremely stable system which
> is very resistant to computer crashes, even if they occur in the middle
> of writing processes.
>
> Our engine is *not* a memory-based system like your "gauntlet" suggests
> for most systems. [1]
> Every change is written to the database file immediately after it is
> applied. commit() flushes indices.
>
> We are on the way to a 100% secure system.
> Could I assure you that we will get there?
>
> Kind regards,
> Carl
> ---
> Carl Rosenberger
> db4o - database for objects - http://www.db4o.com
>
>
> [1] One of the popular pure Java SQL databases also is a
> memory-based-system by the way.
>
>
>
Received on Wed Nov 28 2001 - 13:41:14 CET