数据存储在磁盘上的排列方式会影响I/O服务的总时间。假设每磁道划分成10个物理块，每块存放1个逻辑记录。逻辑记录R1，R2，…，R10存放在同一个磁道上，记录的安排顺序如表1-1所示。

 假定磁盘的旋转速度为20ms/周，磁头当前处在R1的开始处。若系统顺序处理这些记录，使用单缓冲区，每个记录处理时间为4ms，则处理这10个记录的最长时间为(22)；若对信息存储进行优化分布后，处理10个记录的最少时间为(23)。

(79)

(77)

(78)

(76)

The Rational Unified Process (RUP) is a software engineering process, which captures many of best practices in modern software development. The notions of use-cases and (71) have been proven to be an excellent way to capture function requirements. RUP can be described in two dimensions-time and content. In the time dimension, the software lifecycle is broken into cycles. Each cycle is divided into four consecutive (72) which is concluded with a well-defined (73) and can be further broken down into (74) - a complete development loop resulting in a release of an executable product, a subset of the final product under development, which grows incrementally to become the final system. The content structure refers to the disciplines, which group (75) logically by nature.

(72)

(74)

设关系模式R＜U,F＞，其中U{H,I,J,K,L}，若F={H→IJ,J→K,IJK→L,L→H,L→K)，则F的最小函数依赖集Fmin={(54)}，关系模式R的候选关键字是(55)。

设有职工实体Employee(职工号，姓名，性别，年龄，通信地址，家庭成员)，其中通信地址记录了邮编、省、市和街道信息；家庭成员记录了职工亲属的姓名。

 职工实体中的通信地址是一个(51)属性；为了将数据库模式设计的更合理，对于家庭成员属性(52)。

(70)