Path: text.usenetserver.com!out01b.usenetserver.com!news.usenetserver.com!in02.usenetserver.com!news.usenetserver.com!postnews.google.com!34g2000hsz.googlegroups.com!not-for-mail From: JOG Newsgroups: comp.databases.theory,comp.object Subject: Re: Object-relational impedence Date: Mon, 3 Mar 2008 11:21:37 -0800 (PST) Organization: http://groups.google.com Lines: 38 Message-ID: References: <0cd61579-0f26-422c-9aec-908ffdea59ff@i7g2000prf.googlegroups.com> <47cc494c$0$4037$9a566e8b@news.aliant.net> NNTP-Posting-Host: 128.243.220.41 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: posting.google.com 1204572098 25044 127.0.0.1 (3 Mar 2008 19:21:38 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Mon, 3 Mar 2008 19:21:38 +0000 (UTC) Complaints-To: groups-abuse@google.com Injection-Info: 34g2000hsz.googlegroups.com; posting-host=128.243.220.41; posting-account=H0ckjQoAAADRgkguzQRGVwl65wXgA5te User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.8.1.11) Gecko/20071127 Firefox/2.0.0.11,gzip(gfe),gzip(gfe) X-HTTP-Via: 1.1 cache3.nottingham.ac.uk:3128 (squid/2.5.STABLE3) Xref: usenetserver.com comp.databases.theory:170246 comp.object:264414 X-Received-Date: Mon, 03 Mar 2008 14:21:38 EST (text.usenetserver.com) On Mar 3, 6:54 pm, Bob Badour wrote: > topmind wrote: > > JOG wrote: > > >>On Mar 3, 2:07 pm, Thomas Gagne wrote: > > >>>All attempts by applications to access a DB's tables and columns > >>>directly violates design principles that guard against close-coupling. > >>>This is a basic design tenet for OO. Violating it when jumping from OO > >>>to RDB is, I think, the source of problem that are collectively and > >>>popularly referred to as the object-relational impedance mismatch. > > >>I wondered if we might be able to come up with some agreement on what > >>object-relational impedence mismatch actually means. I always thought > >>the mismatch was centred on the issue that a single object != single > >>tuple, but it appears there may be more to it than that. > > >>I was hoping perhaps people might be able to offer perspectives on the > >>issues that they have encountered. One thing I would like to avoid > >>(outside of almost flames of course), is the notion that database > >>technology is merely a persistence layer (do people still actually > >>think that?) - I wonder if the 'mismatch' stems from such a > >>perspective. > > > This came up in a nearby message. I borrowed the following text from > > wikipedia: > > The text had too many blatant errors to start enumerating them all. The > problem with wikipedia is any ignorant fool can just start typing > nonsense. Even when one follows the requirements for references to > primary sources, the quality of the end product can vary over many > orders of magnitude. And yet wikipedia entries are often remarkably half-decent. However not in this case - the entry is a convloluted mess, and actually instigated my question.(I often wonder if it would not be better if opposing views on wikipedia could be treated as separate articles rather than the standard mish mash).