Re: Stateless clients and locking schemes (or rather isolation levels)


AAhhh

--- Serge Rielau <srielau@xxxxxxxxxx> wrote:

> CDRTIME column. It's primary purpose is for
> replication, but "optimistic
> locking" has the same problem as replication:
> Finding and resolving conflicts without locks.
>
http://publib.boulder.ibm.com/infocenter/ids9help/topic/com.ibm.sqls.doc/sqls109.htm
>
>
> Cheers
> Serge
>
>
> DL Redden <redden96@xxxxxxxxx> wrote on 07/27/2005
> 12:30:04 PM:
>
> > What does "Informix supports versioning columns"
> refer
> > to?
> >
> > --- Serge Rielau <srielau@xxxxxxxxxx> wrote:
> >
> > > Superboer wrote:
> > > >>This is a funny way of looking at. Obviously
> > > Oracle's none locking
> > > >>engine is perfectly suited to scaling multi
> user
> > > applications,
> > > >>particularly when most people are developing
> for
> > > stateless clients.
> > > >
> > > >
> > > > ahum does the above explain why informix was
> > > faster on a 5 times
> > > > smaller machine then obstacle...????
> > > >
> > > > Superboer.
> > > >
> > > Changed the subject lines and following up on
> what
> > > Knut started.
> > >
> > > How does Oracles snapshot isolation help with
> > > stateless clients.
> > > To the best of my knowledge snapshot semantics
> only
> > > operate on either a
> > > statement or a transaction level. In a stateless
> > > scenario I'd assume
> > > that teh application transaction covers at least
> two
> > > database
> > > transactions. A read phase wher the resultset is
> > > displayed at the client
> > > and a separate write phase where the modified
> data
> > > is written back.
> > > How does snapshot isolation help here?
> > > Informix supports versioning columns which can
> be
> > > used by the app to
> > > prevent overwriting other users changes across
> DB
> > > transaction boundaries.
> > > MS SQL server has a somewhat similar approach
> and
> > > even buried optimistic
> > > locking into the cursor logic (not applicable in
> a
> > > stateless enviroment
> > > (no cursor open).
> > > I see tha value of snapshot isolation for
> certain
> > > purposes. I don't see
> > > it for a 3 tier web application....
> > >
> > > Thoughts?
> > > Cheers
> > > Serge
> > > --
> > > Serge Rielau
> > > DB2 SQL Compiler Development
> > > IBM Toronto Lab
> > >
> >
>
>

sending to informix-list
.

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