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From: gupta@fornax.UUCP (Ranabir Gupta)
Newsgroups: comp.databases
Subject: Long (Design) Transactions
Keywords: What-if analyses, shadow files
Message-ID: <2151@fornax.UUCP>
Date: 20 Feb 91 03:03:14 GMT
Organization: School of Computing Science, SFU, Burnaby, B.C. Canada
Lines: 34

I'm looking at a planning/design application where lots of
'what-if' (hypothetical) design-related planning is involved
using information about 1000+ objects. What complicates matters
is that other planners will also be looking at the data (and
wanting to modify it) and the world which the data models will
also be changing and wanting to update the data to reflect
the changes.

Many updates may be considered before some are committed to the
database by the planner. In a sense, each transaction will be a 
long one (upto hours) instead of the quick commercial transactions.
Otherwise, the requirements of maintaining integrity of the data
during the transaction are (almost) the same as in the usual case.
Obviously, all the data which may possibly be updated in the course
of the transaction should not be locked, for fear of hobbling all the
other planners. The alternative that seems best is to develop some
sort of warning mechanism to simultaneous accessors of the same
information for read and update (even for read, because subsequent 
plans may depend on a planner assuming that some data which (s)he 
is looking at won't change during her/his deliberations) and some
conflict resolution strategy.

Question is:
Are there any systems around which target this sort of application ?
Are there any research papers that do ?
Partial addressing of this question ?

I am not bound (at present) to any particular environment (object-
oriented/relational etc.) but would 'prefer' one which leans towards
established technologies. 

Gurus, help!    if people email me at 'gupta@cs.sfu.ca', I'll
summarize for the net, if there's sufficient interest. Of course,
any response could just as well be posted. Thanks in anticipation.