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

What does "Informix supports versioning columns" refer to? --- Serge Rielau <srielau@ca.ibm.com> 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