抄自SQL Server Books Online:Clustered Indexes(簇索引)
Clustered indexes have one row in sysindexes with indid = 1. The pages in the data chain and the rows in them are ordered on the value of the clustered index key. All inserts are made at the point the key value in the inserted row fits in the ordering sequence.Nonclustered Indexes(非簇索引)
Nonclustered indexes have the same B-tree structure as clustered indexes, with two significant differences:
1.The data rows are not sorted and stored in order based on their nonclustered keys.
2. The leaf layer of a nonclustered index does not consist of the data pages. Instead, the leaf nodes contain index rows. Each index row contains the nonclustered key value and one or more row locators that point to the data row (or rows if the index is not unique) having the key value.
Clustered indexes have one row in sysindexes with indid = 1. The pages in the data chain and the rows in them are ordered on the value of the clustered index key. All inserts are made at the point the key value in the inserted row fits in the ordering sequence.Nonclustered Indexes(非簇索引)
Nonclustered indexes have the same B-tree structure as clustered indexes, with two significant differences:
1.The data rows are not sorted and stored in order based on their nonclustered keys.
2. The leaf layer of a nonclustered index does not consist of the data pages. Instead, the leaf nodes contain index rows. Each index row contains the nonclustered key value and one or more row locators that point to the data row (or rows if the index is not unique) having the key value.
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