Consider a database containing not only base relations but also stored derived relations (also called materialized or concrete views). When a base relation is updated, it may also be necessary to update some of the derived relations. This paper gives sufficient and necessary conditions for detecting when an update of a base relation cannot affect a derived relation (an irrelevant update), and for detecting when a derived relation can be correctly updated using no data other than the derived relation itself and the given update operation (an autonomously computable update). The class of derived relations considered is restricted to those defined by PSJ -expressions, that is, any relational algebra expressions constructed from an arbitrary number of project, select and join operations (but containing no self-joins). The class of update operations consists of insertions, deletions, and modifications, where the set of tuples to be deleted or modified is specified by a selection condition on attributes of the relation being updated.

AlTALURI ET AL. 43 *Trademark or registered trademark of International Business Machines Corporation.

No abstract

No abstract

At the MRS Conference, 2000, Rupert Howell in a keynote speech attacked the research industry for failing to innovate or adapt to change. The authors take up the challenge of trying to understand the nature of the antipathy that often exists between advertising agency and research people, so as to see how it might be overcome. Analysis of the speech and responses to it make clear that the main contention concerns quantitative pre-testing. Three hypotheses are raised: 1) researchers and planners have different expectations from research; 2) they have different mental models about how advertising works; 3) they are fundamentally different people. Evidence is adduced confirming all three. Mental models quoted include those of Millward Brown, Hall & Partners, HPI, TRBI, low-involvement processing, persuasion shift testing. These researchers’ models are contrasted with opinions from a sample of planners. That researchers and planners are different people is confirmed by results of a survey among senior researchers and planners using the Social Styles Inventory Model (described in appendix) to establish personality type. Ends with a series of recommendations for avoiding the conflict: build long-term relationships with clients, be honest and open, insist on proper briefings, involve the marketing director, understand and explain the advertising strategy and the brand/consumer relationship, ensure that enough time is devoted to the job, how to deliver bad news, understand the difference between idea and execution, use research early in the creative process, avoid delegating too much responsibility to junior people. Clients also need to appreciate the limits of research, understand, respect and trust the researcher, allow enough time and be prepared to pay for quality. Winner of the 2001 ISBA Award.