SQL Server Indexing Interview Question and Answers - Part 1

1. What is a Covering Index ?
An index that is constructed such that SQL Server can completely satisfy queries by reading only the index is called a covering index.
2. What is a Filtered Index ?
A fi ltered index is simply an index with a WHERE clause.
3. What is a Fillfactor ?
To control the rate at which page splits occur, you can specify a fi ll factor for the index. FILLFACTOR specifies the percentage of free space that should be left on the leaf level of an index during creation or rebuild.
4. What happens when an Index is created with ONLINE = ON?
When an index is created using the ONLINE = ON option, SQL Server allows changes to the table during the creation of the index by using the version store within the tempdb database.
5. How much of Data an XML datatype can hold ?
An XML data type can contain up to 2 gigabytes (GB) of data in a single column.
6. What is an XML Index ?
To improve the performance of queries against XML data, you can create a special type of index called an XML index. There are 2 types of indexs : primary and secondary. Primary: A primary XML index is built against all the nodes within the XML column. Secondary : Secondary indexes are created on PATH, VALUE, or PROPERTY.
7. What are Spatial indexes ?
Indexes created on geometry or geography are called Spatial indexes.

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