Managing Indexes

Chia sẻ: Lê Trinh | Ngày: | Loại File: PPT | Số trang:34

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Classification of Indexes An index is a tree structure that allows direct access to a row in a table. Indexes can be classified based on their logical design or on their physical implementation. The logical classification groups indexes from an application perspective, while the physical classification is derived from the way the indexes are stored. Single column and concatenated indexes A single column index has only one column in the index key—for example, an index on the employees number column of an employees table. A concatenated index, also known as a composite index, is created on multiple columns in a table. Columns in a...

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