On 08/10/05, Martijn van Oosterhout <kleptog@xxxxxxxxx> wrote: > On Sat, Oct 08, 2005 at 03:32:00PM +0400, Nikolay Samokhvalov wrote: > > http://chernowiki.ru/Dev/PostgreSQLComparedWithSQL2003AndOracleSQLServerDB2Etc > > > > Perhaps I'm wrong with some issues - any comments are welcome. > > The only thing I can comment on is updatable views. You can make > updatable views using RULEs. The only thing is that they're not > *automatically* updateable. OK, I'll make this correction. But for me, updatable views are views for which DBMS supports insert/update/delete operations as for tables. Ideally, people shouldn't distinguish table and view - that's what theory stands for (see Date's thoutghs about it: http://www.dbmsmag.com/int9410.html, he also has a cycle of articles on this theme: http://www.dbdebunk.citymax.com/page/page/622302.htm). PostgreSQL doesn't support updates even for simple views such as select-with-restriction. What it does support - not updatable views, but some kind of INSTEAD OFF triggers (another form of). > > In theory, if someone came up will a program that from given <view > definition> produced the appropriate INSERT, UPDATE and DELETE rules, > it might be incorporated. Currently you just have to do it manually... There is a good theory (Date), but it cannot be implemented for any practical DBMS. The cause lies in differences between theory and practice. And the major difference is possibility to define tables w/o PK (in other words, possible duplicate rows). Nevertheless, all major commercial RDMSs support some subset of views that can be updated.. SQL:2003 defines a quite large subset, but the definition is pretty mazy... > > Case-insensetive text comparisons can be acheived using the citext > module on gborg. > > http://gborg.postgresql.org/project/citext/projdisplay.php Thanks for the link, I'll try it. However, I suppose that such basic feature as support collations should be implemented in core. > > Have a nice day, > -- > Martijn van Oosterhout <kleptog@xxxxxxxxx> http://svana.org/kleptog/ > > Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a > > tool for doing 5% of the work and then sitting around waiting for someone > > else to do the other 95% so you can sue them. > > > -- Best regards, Nikolay ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
