tailieunhanh - A Language Facility for Designing Database-Intensive Applications

Conditional branch instructions present a signicant prob- lem for modern pipelined CPUs because the CPUs do not know in advance which of the two possible outcomes of the comparison will happen. CPUs try to predict the outcome of branches, and have special hardware for maintaining the branching history of many branch instructions. A mispre- dicted branch incurs a substantial delay; [4] reports that the branch misprediction penalty for a Pentium II proces- sor is 17 cycles. For Pentium 4 processors, the minimum penalty is 17 cycles [1] with a slightly higher average penalty; the pipeline for a Pentium 4 is 20 stages deep. In our ex- perimental results that measure the. | A Language Facility for Designing Database-Intensive Applications JOHN MYLOPOULOS University of Toronto PHILIP A. BERNSTEIN Harvard University and HARRY K. T. WONG IBM Research Laboratory TAXIS a language for the design of interactive information systems . credit card verification student-course registration and aứline reservations is described. TAXIS offers relational database management facilities a means of specifying semantic integrity constraints and an exception-handling mechanism integrated into a single language through the concepts of class property and the IS-A generalization relationship. A description of the main constructs of TAXIS is included and theừ usefulness illustrated with examples. Key Words and Phrases applications programming information system relational data model abstract data type semantic network exception handling CR Categories 4 22 1. INTRODUCTION Motivation A primary goal of database management is the reduction of software costs by promoting data independence. In the database literature practical aspects of the development of applications software that use a database system are often treated as peripheral to the main thrust of database research. Until recently applications programming has usually been considered in the context of a data sublanguage embedded in a conventional applications programming language. Some of the better examples of this approach include papers by Date 5 and Schmidt 17 Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for dứect commercial advantage the ACM copyright notice and the title of the publication and its date appear and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise or to republish requứes a fee and or specific permission. This work was supported in part by the National Science Foundation under Grant ENG77-05720 in part by the .

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