Re: rowid

Michael, You are right about it. I think it is extremely stupid programming to remember rowid as a static data and I can be almost sure that this is not what Joesph was asking. I think what he meant was using rowid to process data in cursors (instead of primary keys). Ravi ----- Original Message ----- From: "Michael Mueller" <michael.mueller01@kay-mueller.de> To: <wolphie@hotmail.com> Cc: "rkusenet" <rkusenet@sympatico.ca>; <informix-list@iiug.org> Sent: Tuesday, May 20, 2003 09:06 Subject: Re: rowid > Joseph, > > I am not sure that this is relevant. But there has been another change > in this area. In the olden days a row was guaranteed to keep it's rowid > for it's life time (until it was deleted). This is not true anymore. All > versions that support the inplace alter table feature may internally > delete and reinsert rows for tables that have been altered in the past > using "alter table". This happens during updates of rows that happen to > be on the same disk page. And it results in a change of rowid because > the rowid is built from <logical page> + <slot number>. > > This deleting and reinserting is done when shorter rows were altered > into longer ones. When the page is finally converted to the new format > (it's always done for the whole page) there may not be enough space on > it for all the rows. > > For programs that remember rowids this can be quite a surprise. > > Michael > > rkusenet wrote: > > "Smitty" <wolphie@hotmail.com> wrote in message news:4f39af7f.0305190604.414c07a@posting.google.com... > > > >>We have 1800+ 4GL programs written using Informix SE 4.0 and have > >>needed to upgrade for a LONG time. We have a 5-user version of > >>Informix IDS 7.31.UD5-1 to test with. Someone told us that the newer > >>versions of Informix don't support "rowid", which is included in a lot > >>of our code thanks to the FourGen CASE tools. We are having trouble > >>getting a definitive answer to this question, does anyone know when or > >>if Informix products stopped using rowid? > >>Thanks! > > > > > > rowid will not work if your table is fragmented, unless you create the > > table WITH ROWID clause. Now given that you are currently using SE 4.0, > > if you move your schema as it is, then there is no question of fragmentation. > > Hence your old programs can safely use rowids, as long as you don't change > > the schema and start fragmenting. > > > > Ravi > > > > > > > > > -- > > === Michael Mueller ================== > Tel. + 49 8171 63600 > Fax. + 49 8171 63615 > Web: http://www.mm.kay-mueller.de > http://www.planets.kay-mueller.de > ====================================== >