MS SQL Server Concepts and Programming Question:
How To Defragment Table Indexes?
Answer:
When a table index is fragmented to a certain percentage, you need to defragment the index to maintain its performance level. There are 3 ways to defragment:
1. "ALTER INDEX index_name ON table_name REORGANIZE" - Defragmenting the specified index performed in online mode. No locks applied on affected table. Used for indexes with a small fragmentation percentage.
2. "ALTER INDEX index_name ON table_name REBUILD" - Defragmenting the specified index performed in offline mode by default. It can be performed in online mode. Used for indexes with a large fragmentation percentage.
3. "CREATE INDEX ... WITH (DROP_EXISTING = ON)" - Re-creating the specified index. The definition of the index can be changed.
1. "ALTER INDEX index_name ON table_name REORGANIZE" - Defragmenting the specified index performed in online mode. No locks applied on affected table. Used for indexes with a small fragmentation percentage.
2. "ALTER INDEX index_name ON table_name REBUILD" - Defragmenting the specified index performed in offline mode by default. It can be performed in online mode. Used for indexes with a large fragmentation percentage.
3. "CREATE INDEX ... WITH (DROP_EXISTING = ON)" - Re-creating the specified index. The definition of the index can be changed.
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