Path: news.easynews.com!newsfeed1.easynews.com!easynews.com!easynews!uunet!dfw.uu.net!an02.austin.ibm.com!ausnews.austin.ibm.com!sp15ce20.hursley.ibm.com!not-for-mail From: "Paul Vernon" Newsgroups: comp.databases.theory Subject: Re: What is integrated? Date: Mon, 11 Nov 2002 22:44:11 -0000 Organization: IBM Hursley Lines: 39 Message-ID: References: <0ucnsu4p1a30feev13v556269hjhfbfmh3@4ax.com> NNTP-Posting-Host: dyn-9-140-177-100.warwick.uk.ibm.com X-Trace: sp15at20.hursley.ibm.com 1037096512 36512 9.140.177.100 (12 Nov 2002 10:21:52 GMT) X-Complaints-To: news@hursley.ibm.com NNTP-Posting-Date: Tue, 12 Nov 2002 10:21:52 +0000 (UTC) X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Xref: newsfeed1.easynews.com comp.databases.theory:23599 X-Received-Date: Tue, 12 Nov 2002 03:51:10 MST (news.easynews.com) "Scotty" wrote in message news:tversusqgv74c4oa219emcvsi1n1orilt4@4ax.com... [snip] > Christ it sounds like a load of gibberish when I re-read it. You said it! But it's not much worse than a lot else that is written on this ill founded subject. Some pointers: 1-jan-2002 and 01-01-02 are not different domains. They are different representations of the same value from a particular domain (that I tend to call TimePoint - i.e. a TimeDuration from some fixed point in time). This doesn't mean that your data sources will recognise such logical differences however. Logically, and you are asking on c.d.theory here, you should correctly model your data sources first (noting things like domains, domain representations, domain definitions, constraints, attributes and relations), then normalise them (including adding then normalising temporal attributes if history is required to be kept) and only then integrate them. > These ETL tools are often responsible for the success of an ODS project Do you know that from first hand experience, from some closely reasoned argument, or are you just guessing (or worse, taking somebody else's word for it)? Maybe you should try to rigorously define what 'problem' an ETL is attempting to 'solve'. Regards Paul Vernon Business Intelligence, IBM Global Services