Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Martin Gregorie Newsgroups: comp.lang.java.programmer Subject: Re: ORMs comparisons/complaints. Date: Sat, 4 Jan 2014 16:02:35 +0000 (UTC) Organization: A noiseless patient Spider Lines: 38 Message-ID: References: <%JGtu.29103$Wm1.26832@fx17.iad> <52c4d306$0$302$14726298@news.sunsite.dk> <7LednV8eOcPXQVrPnZ2dnUVZ8gGdnZ2d@bt.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Sat, 4 Jan 2014 16:02:35 +0000 (UTC) Injection-Info: mx05.eternal-september.org; posting-host="e5160e2be48f1ea550cf61512446f525"; logging-data="29284"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+MV+CDlryekGWNQjeq2BSgo/zJ8nNeBVA=" User-Agent: Pan/0.139 (Sexual Chocolate; GIT bf56508 git://git.gnome.org/pan2) Cancel-Lock: sha1:yyLA7HmxvUkdbVDtP1c/IH6Wox4= Xref: csiph.com comp.lang.java.programmer:27230 On Sat, 04 Jan 2014 10:02:43 +0000, lipska the kat wrote: > How many times in your career have you actually changed databases > mid-stream? I'm not talking about prototyping, where you may use a > simple lightweight database almost as a stub for prototyping purposes. > Never - and that includes prototyping. IME a reason for prototyping has been to check that the projected data model can give the required performance on the selected database, which requires the prototype to use the target DBMS. I think a more likely case is when you're building a product that is required to run on a range of databases. > The idea that objects need to be 'identified' is a direct consequence of > the fact that the method of identifying the data needed to populate a > 'persistent object' where that data is stored in an RDBMS is the 'key' > and this is the point I'm trying to make. > Many real-world objects do have a natural identifier though and, as its something that people use to say which instance they are referring to, any computer system that deals with them muse use it as an identifier. Almost any product that complex or expensive enough to carry a guarantee will have a serial number. Many other items, e.g. musical compositions, can have a very complex identifier. For instance, a music librarian will tell you than that many classical compositions don't have a 'name' and can only be unambiguously identified by some combination of up attributes. The International Federation of Library Associations and Institutions (IFLA) defined a set of 14 attributes at least 35 years ago. Note that none of these are alternate identifiers: all 14 attributes are needed to create one unique identifier. -- martin@ | Martin Gregorie gregorie. | Essex, UK org |