Path: text.usenetserver.com!out03a.usenetserver.com!news.usenetserver.com!in02.usenetserver.com!news.usenetserver.com!postnews.google.com!i7g2000prf.googlegroups.com!not-for-mail From: JOG Newsgroups: comp.databases.theory,comp.object Subject: Object-relational impedence Date: Mon, 3 Mar 2008 08:52:10 -0800 (PST) Organization: http://groups.google.com Lines: 18 Message-ID: <0cd61579-0f26-422c-9aec-908ffdea59ff@i7g2000prf.googlegroups.com> NNTP-Posting-Host: 128.243.220.21 Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: posting.google.com 1204563131 5821 127.0.0.1 (3 Mar 2008 16:52:11 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Mon, 3 Mar 2008 16:52:11 +0000 (UTC) Complaints-To: groups-abuse@google.com Injection-Info: i7g2000prf.googlegroups.com; posting-host=128.243.220.21; 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 cache1.nottingham.ac.uk:3128 (squid/2.5.STABLE3) Xref: usenetserver.com comp.databases.theory:170221 comp.object:264389 X-Received-Date: Mon, 03 Mar 2008 11:52:11 EST (text.usenetserver.com) 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.