Indexes are specialized data structures that operate on tables (and sometimes views) in the database engine used to aid in the searching for and sorting of data. Indexes are vital to the database engine returning results quickly. As data is modified in the underlying tables that the indexes operate on, the indexes become fragmented. Fragmentation is when the logical ordering of an index does not match the physical ordering of the underlying table or view. As the indexes become more and more fragmented, query times can begin to suffer. The remedy to this situation is to either reorganize or rebuild the index in SQL Server 2005.
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