the relational model are not the same
thing; indeed, SQL has little to do
with the relational model.) As for “a…
type should be an interface that does
not name its implementations,” and
to the extent we even understand this
remark, types in the relational model
meet this criterion.
We would never publish a critique
of (for example) Hewitt’s actor model
without understanding it well; why
then does he feel he can publish a critique of the relational model, when he
demonstrably does not understand it?
C.J. Date, healdsburg, CA, and
D. mcGoveran, Deerfield Beach, Fl
Reference
1. Date, c.j., Dar wen, h., and lorentzos, n.a. Temporal
Data and the Relational Model. morgan kaufmann,
san francisco, 2003.
Relational model outgrown
Unfortunately, Date and McGoveran
make no good arguments against the
limitations of the relational model, as
outlined in my letter (Jan. 2013), partly
because we are using incommensurable terminology (such as “negation,”
“disjunction,” “concurrency,” and
“abstraction”); for details, see articles
in Proceedings of Inconsistency Robustness 2011 ( http://robust11.org), especially regarding the requirement for
inconsistency robustness. My point is
not to dismiss relational databases as
a failure but to build on their success
and overcome their limitations.
Such an effort must meet several requirements:
Compatibility. All capabilities of
current relational databases must
continue to be implemented; in addition, incrementally integrating inconsistent information from multiple relational databases with incompatible
schemas (something awkward in the
relational model) must become standard practice; and
Natural language + gestures (as lingua
franca for communication with computer
systems). Semantics of natural language
and coordinated gestures of multiple
participants must be expressible. An
important consequence is expressions
and gestures must be able to mutu-
ally refer to each other, something
awkward in the relational model; for ex-
ample, if Alice points her finger at Bob
and charges, “I accuse you of harassing
me,” and Bob retorts, “I deny it!,” then
the mutual co-reference of language
and gesture must be expressible.
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Reference
1. hewitt, c. Tutorial for ActorScript. arxiv. cornell
university, Ithaca, ny, mar. 2013; http://arxiv.org/
abs/1008.2748
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