- Microsoft SQL Server has eigt index types.laptop with database record on 15.4
A database index allows you to quickly find specific data in a database table or indexed view. Database indexes are made up of keys built from table or view columns and contain pointers that map to data location. By designing indexes that support database queries, you can optimize your queries by reducing the amount of data that needs to be read to get the query results. Microsoft SQL Server 2008 uses eight types of indexes. - The clustered index sorts data rows of a table or view by clustered index key values. It uses a B-tree index structure to ensure fast row retrieval.
- With a nonclustered index, the rows are stored in order of the index key values, but they are not sorted in any particular order. A nonclustered index contains the nonclustered key value along with a row locator that indicates the data row in the clustered index, which has the key value.
- In a unique index, the index key has no duplicate values and each row in the table or view is unique.
- An index with included columns is a nonclustered index that has been extended to include both key and nonkey columns.
- A full-text index is a token-based functional index created by the Microsoft Full-Text Engine. It is used for optimizing word searches of character strings.
- With a spatial index, you can perform operations on spatial data in a more efficient manner within a column of the geometry data type. Using a spatial index, you streamline spatial operations.
- A filtered index is good for queries of a well-defined set of data. It enhances query performance by indexing only some of the rows in a table.
- An XML index is created on XML data type columns. It allows representation of XML binary large objects (BLOBs) in the XML data type column. If you run frequent queries on XML columns, this will make query processing more efficient.
