SQL Joins vs Single Table : Performance Difference?

sql join normalization
zsharp picture zsharp · Jan 25, 2009 · Viewed 13.7k times · Source

I am trying to stick to the practice of keeping the database normalized, but that leads to the need to run multiple join queries. Is there a performance degradation if many queries use joins vs having a call to a single table that might contain redundant data?

Answer

Mitch Wheat picture Mitch Wheat · Jan 25, 2009

Keep the Database normalised UNTIL you have discovered a bottleneck. Then only after careful profiling should you denormalise.

In most instances, having a good covering set of indexes and up to date statistics will solve most performance and blocking issues without any denormalisation.

Using a single table could lead to worse performance if there are writes as well as reads against it.

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