Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!drn.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: Sun, 05 Jun 2005 22:10:02 -0500 Message-Id: From: Kenneth Downs Subject: Re: Proving an Upgrade is Possible Newsgroups: comp.databases.theory Date: Sun, 05 Jun 2005 22:26:22 -0400 References: <8vq8n2-0ek.ln1@pluto.downsfam.net> <0fcbn2-375.ln1@pluto.downsfam.net> Organization: Secure Data Software, Inc. User-Agent: KNode/0.8.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7Bit Lines: 50 X-Trace: sv3-peVf4JGd0zz4NPModBpQA+s+dleNjTbW1jX/Ay6GkRFHigoUjA350H0M+iIInY7PPaWGbSVGFrf1Vpf!sLhS9Fnjwum7kF5pdfcbp7LGbH8t+XdKioC6FhqBZWqgc0sxQxSbMT/ugnU= 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:31223 mountain man wrote: > "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? Yes. > > The testing with any live data happens at a later stage. > Is this correct? > No, I want this to be included in the analysis of the schema change, so it checks both: mS(2): the destination schema (or meta-State) Delta-mS: the change in schema (or change in meta-State) Delta-S: Change in state of user data -- Kenneth Downs Secure Data Software, Inc. (Ken)nneth@(Sec)ure(Dat)a(.com)