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SQL Server Database Optimization and Query Fundamentals
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What are the situations when an index might not be picked up?
AnswerClick to flip back
A
Leading column in the index is not part of the search arguments
B
Data types are not matching while doing a join
C
Optimizer decides that table scan is better
💡 Explanation:
Indexes are ignored if the leading column is missing from search arguments, or if mismatched data types force implicit conversions. The optimizer may also bypass an index for a table scan if selectivity is low. Index names do not affect optimizer decisions.