Microsoft® SQL Server 2012 Unleashed

Indexing Guidelines

In general, you need to be sure not to over index your tables, especially for tables that require good performance for data modifications! Common mistakes include creating redundant indexes on primary keys that already have primary key constraints defined or creating multiple indexes with the same set of leading columns. You should understand when an index is required based on need, not just the desire to have an index. Also, you should make sure that the indexes you define have sufficient cardinality to be useful for your queries. In most performance and tuning engagements that we do, we spend a good portion of our time removing indexes or redefining them correctly to better support the queries being executed against the ...