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

AAhhh --- Serge Rielau <srielau@ca.ibm.com> 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@yahoo.com> wrote on 07/27/2005 > 12:30:04 PM: > > > 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