Spending $5k to learn how database indexes work
I feel like indexes are a pretty fundamental type of DB knowledge. In fact I&#x27;d say it&#x27;s table stakes knowledge you should have if you&#x27;re working with them. Further more, knowing that ForeignKeys typically apply an index to that column is also in my head basic knowledge. I&#x27;m sorry you got burnt, and congrats on learning a lesson, but you could have gotten the same knowledge by ever googling MySql ForeignKeys and saved yourself a headache.<p>In fact it&#x27;s like a big bullet point near the top of the docs page.<p>&quot;MySQL requires indexes on foreign keys and referenced keys so that foreign key checks can be fast and not require a table scan. In the referencing table, there must be an index where the foreign key columns are listed as the first columns in the same order. Such an index is created on the referencing table automatically if it does not exist. This index might be silently dropped later if you create another index that can be used to enforce the foreign key constraint. index_name, if given, is used as described previously.&quot;<p>I&#x27;m not entirely sure why buzz around &quot;developer learns basic knowledge&quot; has this on the front page.