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⟩ How To Rebuild Indexes with ALTER INDEX ... REBUILD?

When an index is defragmented to a large percentage, like > 30%, you can use the "ALTER INDEX ... REBUILD" statement to rebuild the index. Here is a tutorial exercise on rebuilding indexes:

UPDATE ggl_links_indexed SET url = REVERSE(url)

WHERE id <=50000;

GO

(50000 row(s) affected)

SELECT i.index_id, i.name, s.avg_fragmentation_in_percent

FROM sys.dm_db_index_physical_stats (

DB_ID(N'GlobalGuideLineDatabase'),

OBJECT_ID(N'ggl_links_indexed'),

DEFAULT, DEFAULT, DEFAULT) s, sys.indexes i

WHERE s.object_id = i.object_id

AND s.index_id = i.index_id;

GO

0 NULL 0.574712643678161

2 ggl_links_url 85.0142045454545

3 ggl_links_counts 0.448430493273543

ALTER INDEX ggl_links_url ON ggl_links_indexed REBUILD;

GO

SELECT i.index_id, i.name, s.avg_fragmentation_in_percent

FROM sys.dm_db_index_physical_stats (

DB_ID(N'GlobalGuideLineDatabase'),

OBJECT_ID(N'ggl_links_indexed'),

DEFAULT, DEFAULT, DEFAULT) s, sys.indexes i

WHERE s.object_id = i.object_id

AND s.index_id = i.index_id;

GO

0 NULL 0.574712643678161

2 ggl_links_url 0

3 ggl_links_counts 0.448430493273543

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