Don’t use DISTINCT as a “join-fixer”

I’ve quietly resolved performance issues by re-writing slow queries to avoid DISTINCT. Often, the DISTINCT is there only to serve as a “join-fixer,” and I can explain what that means using an example.

The Temporary Synonym

The EXCEPT Query

Multiple Encryptions

Normalize strings to optimize space and searches

While this article is specifically geared to SQL Server, the concepts apply to any relational database platform. The Stack Exchange network logs a lot of web traffic – even compressed, we average well over a terabyte per month.

Parsing Strings

Adding a FK in a CREATE TABLE

Extracting JSON

The Column Synonym

TRUNCATE an FK