在利用 SQL Server 查询分析器的执行计划中,会有许多扫描方式,其中就有 Clustered Index Scan 与 Clustered Index Seek,这二者有什么区别呢? Clustered Index,为聚集索引,表示它们使用的都是聚集索引扫描。 Scan 表示它扫描一个范围或者是全部内容,Seek 表示扫描特定范围内的行。也就是说 Scan 并不知道要目标行是...
Clustered Index,为聚集索引,表示它们使用的都是聚集索引扫描。 Scan 表示它扫描一个范围或者是全部内容,Seek 表示扫描特定范围内的行。也就是说 Scan 并不知道要目标行是哪些,而 Seek 扫描表明我已经知道我要找的目标行是哪些,所以 Seek 一般要快些。 看看下面的语句,哪个(些)是 Scan 扫描,哪些是 Seek 扫描呢...
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小结: “Index Seek”利用“WHERE”来过滤获取的数据, 不需要对表和索引页进行扫描;而“Table Scan”和“Index Scan”需要。 【聚簇索引Unique Clustered Index】 2.4 【Clustered Index Scan/Seek 】 当在WHERE后用到PRCode字段的时候,“Clustered Index Seek”被用到,否则都是Clustered Index Scan SelectPRID, P...
Clustered Index Seek 运算符利用索引的查找功能从聚集索引中检索行。Argument 列包含所使用的聚集索引名称和 SEEK:() 谓词。存储引擎仅使用索引来处理满足此 SEEK:() 谓词的行。它还包括 WHERE:() 谓词,其中存储引擎对满足 SEEK:() 谓词的所有行进行计算,但此操作是可选的,并且不使用索引来完成此过程。
网络聚集索引查找;聚集索引查找要慢;丛集索引搜寻 网络释义
TheArgumentcolumn contains the name of the nonclustered index being used. It also contains the SEEK:() predicate. The storage engine uses the index to process only those rows that satisfy the SEEK:() predicate. It optionally may include a WHERE:() predicate, which the storage engine will ev...
TheArgumentcolumn contains the name of the nonclustered index being used. It also contains the SEEK:() predicate. The storage engine uses the index to process only those rows that satisfy the SEEK:() predicate. It optionally may include a WHERE:() predicate, which the storage engine will ev...
The following example deletes a row from a table that has a clustered index. The output of the execution plan shows that the query optimizer uses theClustered Index Seekoperator to retrieve the specified rows. Copy USE AdventureWorks; GO SET NOCOUNT ON; GO SET SHOWPLAN_ALL ON; GO SELECT Nam...
The following example deletes a row from a table that has a clustered index. The output of the execution plan shows that the query optimizer uses theClustered Index Seekoperator to retrieve the specified rows. Copy USE AdventureWorks; GO SET NOCOUNT ON; GO SET SHOWPLAN_ALL ON; GO SELECT Nam...