Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!border1.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Thu, 04 May 2006 19:48:02 -0500 Date: Thu, 04 May 2006 20:43:53 -0400 From: Kenneth Downs Organization: Secure Data Software User-Agent: Mozilla Thunderbird 1.0.7 (X11/20050923) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.databases.theory Subject: Re: Storing derived and derivable data References: <1145622076.958951.174100@t31g2000cwb.googlegroups.com> In-Reply-To: <1145622076.958951.174100@t31g2000cwb.googlegroups.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Message-ID: Lines: 24 X-Trace: sv3-wcQv58D7vE7kduloVBowfo/spL3URQuuYXjHRZTCr2uROGs5amAVpBhGvzY8+dY4t5it+pQLU9N4QoT!cXkcxBnJE98VvvS5xduxYNw5gB85B62QuuL1MTg0B0/DZnsgE4f4roXDAA== X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.32 Xref: dp-news.maxwell.syr.edu comp.databases.theory:39191 dawn wrote: > Is there database theory that includes identification of > > 1. the fact that values for an attribute either were or could have been > derived? > 2. how values for an attribute were derived? > 3. how values for an attribute could have been derived? > Dawn, hello! Long time no see. I saw your post and decided it was time to end my long exile, you have asked the questions that are at the heart of my company and project. In order to even begin to deal with this question, you have to deal with the 800lb gorilla called "Normalization", which forbids derived data. I wrote an essay on that some months ago, which is here: http://docs.secdat.com/index.php?gppn=Normalization+and+Automation The states basically that derived data is part of life, and since normalization can't deal with it, normalization is not enough to guide serious application development. But you also can't throw it away, because it gives good things.