本文主要介绍sqlserver全文索引(数据库全文索引)的缺点，下面一起看看sqlserver全文索引(数据库全文索引)的缺点相关资讯。
全文检索可以检索varchar类型的文本和图像字段，但是一个表最多只能建立一个全文索引。sql server 2000为存储在图像列中的这些类型的数据引入了全文检索功能。如果没有全文索引，那么字符的模糊查询只能在基表上扫描完整的表(或索引扫描)。执行模糊查询需要完整的表扫描或索引扫描来表示大量的io。如果模糊查询频繁出现，数据库的性能就会下降。为了简单起见，这是一个非常完整和高效的varchar字段全文索引。创建和维护的过程。1.在企业管理器中展开数据库以建立全文索引，右键单击全文目录，并选择一个新的全文目录，如图1所示。您可以将全文目录放在单独的磁盘或磁盘阵列上以提高效率，从而修改全文目录的路径。建议整个全文目录不要以任何形式填充和调度。图1 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 2:接下来，将全文索引添加到特定的表中。全文索引不能建立在视图上，而只能建立在具有唯一索引(主键和唯一索引)的基表上。图2展示了如何在表上构建全文索引。构建t_fulltext表和初始化数据进行演示的脚本如下:创建表t_fulltext(排除identity (1，1)和varchar(256)不为空的标题，writ:29)。t_fullt:10))插入t _ full t:43))插入t_fullt:02))并插入t_fullt:07))插入t_fullt:33))插入t_fullt:30))插入t_fullt:30))插入t_fullt:03)实质性操作)插入t _ full t:30))插t .珠三角地区海水比去年低(15:12))。插入t_fullt:44))插入t_fullt:30))插入t _ full t:56))并插入t _ full t:27))插了t_fulltext的值(省媒体说当局)。图2 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 3:欢迎界面外观如图3所示。图3 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 4:选择唯一的全文索引。index，如图4 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 5:所选全文索引的列。注意，一个表只能创建一个完整的文本索引。;不要选择不好的语言。通过操作sp _ configure 默认全文语言，可以看看默认的词，比如我机器上运行的一个吧。config_value的值是2052，代表简体中文。其他代码表示的语言可以参考网络图书的默认全文关键词。因为sql server对中文分词不是很清楚，所以可以 不要依赖sql server给你带来非常智能的搜索。这意味着全文搜索结果可能包含意外记录，或者您希望出现的记录没有出现。图5 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 6:将表分配给全文目录，如图6所示。您还可以通过该界面创建新的目录。图6 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 7:接下来我们会提示表格填写时间表。为了实时地将基表全文索引列应用于全文索引，我们建议使用下面描述的其他方法进行索引维护。如图7，建议这里不要添加任何日程，直接点击下一步。如果不修改数据，则在完全填充后不会添加其他类型的表级填充。如果执行到这一步，并且没有添加更多的表计划，则基本表数据的更新将不会更新到全文索引。图7 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 8:在完成界面点击完成提示，如图8。请等到下一个界面出现。图8 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 9:在界面点击确定，如图9。由于没有向表中添加时间表，因此需要设置时间表。图9 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 10:在企业资源管理器中点击f_fulltext的表格，如图10所示，选择变更跟踪。选择更改跟踪后，基表数据的后期修改可以反映在全文索引中。特别说明:一旦选择了变更跟踪，根据经验，确实需要完成表的完全填充。如果是在线全文索引数据库，选择变更跟踪会导致性能快速下降，从而导致全文索引。它不 不工作。图10 = = = = = = = = = = = = == = = = = = = = = = = = = = = 11:在企业资源管理器中点击f_fulltext的表格，如图11所示，在后台选择索引更新。通过这一步，全文索引就完成了。因为我们选择了变更跟踪，所以表的完全填充实际上已经开始了。根据经验，300万个全文索引字段长度为50，完成完整填充需要8到10个小时。图11 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 12:我们可以双击全文目录中的全文索引来查看全文目录的属性。如图12所示，状态为idle，项目计数大于0，这意味着完全填充已经完成。图12 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 13:如何查询全文索引(简要介绍)，建议使用contains和freetext谓词。如果关键字仅包含干扰词(有关干扰词的信息，请参考在线干扰词关键字)。select * from t_fulltext其中包含(title，3英尺)将报告以下错误服务器:消息7619，级别16，状态1，第1行全文操作失败。查询子句只包含被忽略的单词。使用下面的语法，可以避免错误，真正查询到正确的记录。select * from t_fulltext，包含(title，× 3x) 13省媒体称，陈 的讲话会唱一首老歌(15 : 30)2005-12-31 23:17: 17.670 10北京公安系统今天全部停查五r ing(17: 30)2005-12-31 23 : 17 : 17.653 17评论:取消农业税使能够分享经济增长的成果(17 echo 0手术第一天突发(17 : 30)2005年12月31日，23:17: 8名患者在福建、广西死亡，患者200人(17:33)。5-12-31 23:17: 17.653(影响行数为5)全文索引在此简单介绍一下，希望能起到作用。
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