14. You’re responsible for SQL Server performance and one of the developers
reports INSERTS are particularly slow. You suspect that a previous developer
has created some redundant nonclustered indexes and these are hindering
INSERT performance. How can you tell if an index is used?
A. Sys.dm_db_index_usage_stats
B. Sys.dm_db_index_request_count
C. Sys.dm_redundant_indexes
D. Sys.dm_db_missing_index_details
Answer A is correct; index usage stats includes a count of user seeks and user
scans, which can be useful to determine whether the optimizer has used an
index since last restart. Options B and C are invalid DMVs. Answer D shows
suggestions for new indexes to create, does not include details on usefulness of
existing indexes.
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