Clustered vs. Non-Clustered Index in a Database
One of the key distinctions in database indexing is between a clustered index and a non-clustered index. Understanding the difference between these two types of indexes is essential in database management and optimization.
Focused Keyword: Clustered vs. Non-Clustered Index
Clustered Index: In a clustered index, the physical order of the data in the table matches the order of the index. This means that the data in the table is sorted based on the indexed columns. A table can have only one clustered index, as the data rows themselves are stored in the order of the clustered index.
Non-Clustered Index: Unlike a clustered index, a non-clustered index stores a copy of the indexed columns separately from the actual data rows. This allows for multiple non-clustered indexes to be created on a single table. When a query uses a non-clustered index, it first looks up the values in the index and then uses pointers to retrieve the corresponding data rows.
In summary, the main difference between a clustered and a non-clustered index is in how the data is physically organized in the database. While a clustered index dictates the physical order of data in the table, a non-clustered index stores the index separately from the data.
When considering index design in your database, it's important to choose the right type of index based on your querying patterns and performance requirements. Both clustered and non-clustered indexes play a crucial role in optimizing database performance and query efficiency.
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