问题 单项选择题

以下关于锁粒度叙述错误的是______。

A.施加X锁和S锁的数据项的大小称为锁粒度

B.锁粒度与事务并发执行的程度和DBMS并发控制的开销密切相关

C.在关系数据库中,可以对数据页、索引页和块等物理单元进行加锁

D.当锁粒度比较大时,事务并发度高,但是系统开销也比较大

答案

参考答案:D

解析: 锁粒度与事务并发执行的程度和DBMS并发控制的开销密切相关。锁粒度越大,系统中可以被加锁的数据项就越少,事务并发执行度也就越低,但是同时系统的开销也就越小。

问答题 简答题
改错题

V. 短文改错(Error correction)(共10小题,计10分)

此题要求改正所给短文中的错误。对标有题号的每一行做出判断:如无错误,在该行右边横线上画一个勾(√);如有错误(每行只有一个错误),则按下列情况改正:

此行多一个词:把多余的词用斜线(\)划掉,在该行右边横线上写出该词,并也用斜线划掉。

此行缺一个词:在缺词处加一个漏字符号(∧),在该行右边横线上写出该加的词。

此行错一个词:在错的词下划一横线,在该行右边横线上写出改正后的词。

注意:原行没有错的不要改。

I am watching televison a few nights ago when I saw something that             96. ________

it made me feel very upset. You see I recognized someone from my past. I       97. ________

once worked in a restaurant who the boss treated his workers very badly.       98. ________

For example, when customers left us a tip he used keep it for himself.         99. ________

I realize that it is quite normal for bosses to get angry from time to         100. ________

time, but he used to get very angry so we did the smallest thing wrong.        101. ________

Almost waiters there only stayed about a month and several waitresses left     102. ________

after only one night. I hated attitude. I decided to leave after a week.       103. ________

So I was very surprised when I turned off my television last Saturday          104. ________

and saw him starring in a cookery programme. I couldn't see my eyes!           105. ________