聚集索引 vs. 非聚集索引
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One table can only have one clustered index. The speed of clustered index is faster than the unclustered index, and clustered index is efficient for range searches.
To build a clustered index, first sort the heap file
- Leave some free space on each block for future inserts
- Index entries direct search for data entries
When inserting lots of data into a clustered index, data may be inserted into the blocks at end of the file. So the order of data is ”close to”, but not identical to, the sort order.