Database Systems (TODS)


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ACM Transactions on Database Systems (TODS), Volume 14 Issue 2, June 1989

A framework for effective retrieval
C. T. Yu, W. Meng, S. Park
Pages: 147-167
DOI: 10.1145/63500.63519
The aim of an effective retrieval system is to yield high recall and precision (retrieval effectiveness). The nonbinary independence model, which takes into consideration the number of occurrences of terms in documents, is introduced. It is...

NFQL: the natural forms query language
David W. Embley
Pages: 168-211
DOI: 10.1145/63500.64125
A means by which ordinary forms can be exploited to provide a basis for nonprocedural specification of information processing is discussed. The Natural Forms Query Language (NFQL) is defined. In NFQL data retrieval requests and computation...

Efficient optimization of simple chase join expressions
Paolo Atzeni, Edward P. F. Chan
Pages: 212-230
DOI: 10.1145/63500.63520
Simple chase join expressions are relational algebra expressions, involving only projection and join operators, defined on the basis of the functional dependencies associated with the database scheme. They are meaningful in the weak instance...

File organization using composite perfect hashing
M. V. Ramakrishna, P.-:1V Larson
Pages: 231-263
DOI: 10.1145/63500.63521
Perfect hashing refers to hashing with no overflows. We propose and analyze a composite perfect hashing scheme for large external files. The scheme guarantees retrieval of any record in a single disk access. Insertions and deletions are simple,...

Maintaining availability in partitioned replicated databases
A. El Abbadi, S. Toueg
Pages: 264-290
DOI: 10.1145/63500.63501
In a replicated database, a data item may have copies residing on several sites. A replica control protocol is necessary to ensure that data items with several copies behave as if they consist of a single copy, as far as users can tell. We...