-- diagnostic des index fragmentés
SELECT * FROM sys.dm_db_index_physical_stats(NULL, NULL, NULL, NULL, NULL)
WHERE avg_fragmentation_in_percent > 10
  AND page_count>64

-- ALTER INDEX .... REORGANIZE --> pas bloquant mais pas top
-- ALTER INDEX .... REBUILD --> bloquant mais top (peut être non bloquant si ed. Enterprise et mode ONLINE)

-- diagnostic des index inutilisés 
-- !!!!!!!!!!!!!!!!!!!!!!!!! ATTENTION : ne pas utiliser si moins de 30 jours de fonctionnement CONTINU du SGBDR
SELECT sqlserver_start_time FROM sys.dm_os_sys_info

SELECT *
FROM   sys.dm_db_index_usage_stats
WHERE  index_id > 1
ORDER  BY user_seeks, user_lookups, user_scans, user_updates DESC

-- recalcul des statistiques
SELECT *
FROM   sys.stats AS s
       CROSS APPLY sys.dm_db_stats_properties(s.object_id, s.stats_id)
WHERE  modification_counter > rows / 10

UPDATE STATISTICS .... WITH FULLSCAN