Does Foreign Key improve query performance?

by

Foreign Keys are a referential integrity tool, not a performance tool. At least in SQL Server, the creation of an FK does not create an associated index, and you should create indexes on all FK fields to improve look up times.

More Related Contents:

  1. How do I obtain a Query Execution Plan in SQL Server?
  2. Count(*) vs Count(1) – SQL Server
  3. What is the best way to paginate results in SQL Server
  4. When should I use CROSS APPLY over INNER JOIN?
  5. INNER JOIN vs LEFT JOIN performance in SQL Server
  6. SQL JOIN vs IN performance?
  7. Is a view faster than a simple query?
  8. Multiple INSERT statements vs. single INSERT with multiple VALUES
  9. How important is the order of columns in indexes?
  10. Can a foreign key be NULL and/or duplicate?
  11. Add Foreign Key relationship between two Databases
  12. What are Covering Indexes and Covered Queries in SQL Server?
  13. SQL Server indexes – ascending or descending, what difference does it make?
  14. Fastest way to remove non-numeric characters from a VARCHAR in SQL Server
  15. SQL Server: Howto get foreign key reference from information_schema?
  16. How can I INSERT data into two tables simultaneously in SQL Server?
  17. Fastest way to determine if record exists
  18. SQL count(*) performance
  19. MS SQL “ON DELETE CASCADE” multiple foreign keys pointing to the same table?
  20. Why is a UDF so much slower than a subquery?
  21. Favourite performance tuning tricks [closed]
  22. Can an INNER JOIN offer better performance than EXISTS
  23. SQL Server SELECT LAST N Rows
  24. SQL Server 2008 paging methods?
  25. What’s the difference between a Table Scan and a Clustered Index Scan?
  26. Slow bulk insert for table with many indexes
  27. The ALTER TABLE statement conflicted with the FOREIGN KEY constraint
  28. Two single-column indexes vs one two-column index in MySQL?
  29. When to use EXCEPT as opposed to NOT EXISTS in Transact SQL?
  30. can we have a foreign key which is not a primary key in any other table?

Leave a Comment