The LOOP, HASH and MERGE Join Types

Today I’ll talk about the available JOIN operator types in SQL Server (Nested Loops, Hash and Merge Joins), their differences, best practices and complexity. For the samples in this post, we’ll use the free AdventureWorks database sample available here: http://msftdbprodsamples.codeplex.com/releases/view/4004 Introduction: What are Join Operators? A join operator is a type of an algorithm which… Read More The LOOP, HASH and MERGE Join Types

The "IGNORE_DUP_KEY" option in Primary Keys and Unique Indexes

Unlike foreign keys, primary keys and unique indexes cannot be “untrusted”. There’s no “NOCHECK” option for unique constraints. The closest there is, is the “ignore_dup_key” option. “Hmm… That sounds interesting”, you must be thinking. But let me stop you right there, buddy. Read this before you go off doing something potentially dangerous… Very, VERY dangerous.… Read More The "IGNORE_DUP_KEY" option in Primary Keys and Unique Indexes