The 3-Minute Test: What do you know about SQL performance?

“SQL-Tuning is black magic 
like alchemy:
It consists of obscure rules,
understood by a handful
of insiders only.”

That is a Myth. SQL databases use well-known algorithms to deliver predictable performance. It is, however, easy to write SQL queries that cannot use the most efficient algorithm, thus delivering unexpected performance.

The following questions show examples that make you believe SQL tuning is black magic. But the explanations at the end need just a few sentences to turn the black magic into science.

Choose your Database

MySQL Oracle PostgreSQL SQL Server