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When to Use Clustered or Non-Clustered Indexes in SQL Server
When to Use Clustered or Non-Clustered Indexes in SQL Server Database indexes are used to improve the speed of database operations in a table with a large number of records. Database indexes (both clustered indexes and non-clustered indexes) are quite simClustered index和non-clustered index的小小总结
Clustered index和non-clustered index本质上都是B-tree数据结构，它们的区别仅仅体现在叶子节点上。 在Clustered index中，索引数据和表数据共同保存在叶子节点中， 在Non-clustered index中，叶子节点保存索引数据以及该索引所指向的数据记录的指针。 所以在Non-clustered index中，需SQL Server 优化器内幕
什么是执行计划？ 怎么生成执行计划？ 数据访问的基本操作：Scan, Seek, bookmark lookup 表连接的三种基本操作： Nested Loop join, Merge Join, Hash Join 后续计划中的坑 子查询的种种 并发线程和我们的hybrid 并发 隔离级别 Isolation的实现 其他杂七杂八的待定 先挖好坑，逐步来填聚簇索引(Clustered Index)和非聚簇索引 (Non- Clustered Index)
索引的重要性数据库性能优化中索引绝对是一个重量级的因素，可以说，索引使用不当，其它优化措施将毫无意义。聚簇索引(Clustered Index)和非聚簇索引 (Non- Clustered Index)最通俗的解释是:聚簇索引的顺序就是数据的物理存储顺序，而对非聚簇索引的索引顺序与数据物理排列顺序无关。举MySQL有哪些索引
（1）数据结构角度 Btree Hash Fulltext R-Tree （2）物理存储角度 聚集索引 clustered index 非聚集索引 non-clustered index （3）从逻辑角度 普通索引：仅快速查询 唯一索引：加速查询+列值唯一（可以有null） 主键索引：加速查询+列值唯一（不可以有null）+表中只有一个 组合索引mysql官方文档Clustered and Secondary Indexes翻译
Every InnoDB table has a special index called the clustered index where the data for the rows is stored. Typically, the clustered index is synonymous with the primary key. To get the best performance from queries, inserts, and other database operations, yWorking with covering indexes
Working with covering indexes As you could read in the indexing basics article, a well-defined index can boost query performance, but there are a few more basic tricks that can have a great impact on how your query is executed. One of the most important i