Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!drn.maxwell.syr.edu!news.maxwell.syr.edu!newscon02.news.prodigy.com!newscon06.news.prodigy.com!prodigy.net!newsfeed-00.mathworks.com!lon-transit.news.telstra.net!lon-in.news.telstra.net!news.telstra.net!news-server.bigpond.net.au!53ab2750!not-for-mail Reply-To: "mountain man" From: "mountain man" Newsgroups: comp.databases.theory References: <8vq8n2-0ek.ln1@pluto.downsfam.net> <0fcbn2-375.ln1@pluto.downsfam.net> Subject: Re: Proving an Upgrade is Possible Lines: 44 Organization: self_organising_systems X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-RFC2646: Format=Flowed; Original Message-ID: Date: Sun, 05 Jun 2005 23:57:27 GMT NNTP-Posting-Host: 203.54.171.185 X-Complaints-To: abuse@bigpond.net.au X-Trace: news-server.bigpond.net.au 1118015847 203.54.171.185 (Mon, 06 Jun 2005 09:57:27 EST) NNTP-Posting-Date: Mon, 06 Jun 2005 09:57:27 EST Xref: dp-news.maxwell.syr.edu comp.databases.theory:31220 "Kenneth Downs" wrote in message news:0fcbn2-375.ln1@pluto.downsfam.net... > mountain man wrote: >> Only a test-conversion will tell you that. This is >> not to say that "proving the schema upgrade is >> possible" ---- at the schema level alone ---- is >> not a worthwhile step in the upgrade path, as >> in the end you need to know about any failure, >> hopefully in advance. > > Not true. In the example above, I showed how you could know before the > conversion that it would fail, without going through the conversion. > > I am seeking the structure of meta data that would offer this ability in > the > general case, that the feature set is complete enough to describe any > application of arbitrary complexity, and that any feature in a particular > case can be known to be possible by analysis before attempting the upgrade > operation. It appears that you are trying to develop a generic process whereby the consistency/validity of schema changes can be tested at the schema level, before the data is dealt with. Essentially, a schematic-change exception check between the old and the new and proposed elements of schema change. Is this correct? The testing with any live data happens at a later stage. Is this correct? -- Pete Brown Falls Creek OZ www.mountainman.com.au