On Thursday 13 November 2003 10:19 am, Oliver Zeigermann wrote:
> Stefano Mazzocchi wrote:
> > BTW, did you guys ever considered the use of a lazy pattern for updates?
> > a-la messaging file system?
> >
> > Basically, you have a memory store that saves in a log file (sort of an
> > equivalent of a messaging file system) some events. the log file is
> > already open and buffered by the OS and the events are small, so this
> > shouldn't be a proble, then in background with a lower priority, a
> > thread 'feeds' the database for backup.
> >
> > The database is therefore used only as a storage system and as the DASL
> > engine... not used for regular node by node operations (which don't
> > require complex SQL queries anyway and could be handled by simple
> > in-memory object operations)
>
> Well, the problem with having persistent store updated asynchronously is
> the transactional stuff. If there is a successful commit, common
> understanding is all ACID properties, including *durability*, are
> fulfilled. This means, you will have to sync to disk upon commit. Thus
> using a low priority storing process will be no good.
>
> As I recently discussed with Christophe some sort of write-back cache
> could not only buffer reading, but also writing. As described above it
> would be synced with persistent store upon commit (or upon prepare?
> hmmm, have to think about it... Comments?) or when it spills.
>
> Unfortunately, this will make things really complicated as - AFAIK - the
> cache itself would need non-blocking locks and a complex spill
> protocoll. Not sure if it is worth it...after the experience with the DB
> store "optimization"... ;)
>
> Oliver
>
>
>
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Wouldn't this mean that the entire store was cached?  I would think this would 
be a problem for large sites.

-Steve

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