David Durant


Stairway to SQL Server Indexes

Filtered Indexes in SQL Server: Stairway to SQL Server Indexes Level 7

A filtered index eliminates unusable entries from the index, producing an index that is as beneficial as, but much smaller than, an unfiltered index. If a certain subset of a table's data is frequently requested, a filtered index can also be a covering index; resulting in a considerable reduction in IO.

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2011-08-24

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Stairway to SQL Server Indexes

Bookmarks in SQL Server Indexes: Stairway to SQL Server Indexes Level 6

A nonclustered index entry consists of search key columns, included columns, and the bookmark. The bookmark value will be either a RID or the clustered index's key, depending upon whether the table is a heap or a clustered index. Choosing the best clustered index for a table requires that you follow three guidelines to ensure that the index key will make a good bookmark.

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2011-08-03

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RegEx Functions II

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Question of the Day

RegEx Functions II

I have this data in a table in a SQL Server 2025 database:

EmailAddressID EmailAddress
7              dylan0@ADVENTURE-WORKS.COM
8              Diane1@ADVENTURE-WORKS.COM
If I run this query, which row(s) are returned?
SELECT top 10
 *
 FROM person.EmailAddress
 WHERE REGEXP_LIKE(EmailAddress, '^d')
 AND BusinessEntityID IN (7,8)

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