Re: Proving an Upgrade is Possible
From: Kenneth Downs <knode.wants.this_at_see.sigblock>
Date: Sun, 05 Jun 2005 22:26:22 -0400
Message-Id: <lvocn2-1k6.ln1_at_pluto.downsfam.net>
>
>
>
> 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?
Date: Sun, 05 Jun 2005 22:26:22 -0400
Message-Id: <lvocn2-1k6.ln1_at_pluto.downsfam.net>
mountain man wrote:
> "Kenneth Downs" <knode.wants.this_at_see.sigblock> wrote in message
> news:0fcbn2-375.ln1_at_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_at_(Sec)ure(Dat)a(.com)Received on Mon Jun 06 2005 - 04:26:22 CEST