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Was this a big deal in the past? In MySQL, yes. It lacked the concept of foreign keys.
by gaius 9y ago
Was this a big deal in the past?
In MySQL, yes. It lacked the concept of foreign keys.
- kondro 9y agoLack of foreign keys does not effect performance. In fact, having foreign keys is a net-negative performance-wise because it means that each foreign key must be checked for every insert/update/delete.
- gaius 9y agoErrm, we're talking about performance of joins
- kondro 9y agoThey don't help with that either.
- Sacho 9y agoPerhaps parent is conflating indexes with constraints? I believe InnoDB creates indexes automatically with foreign keys.
- ComputerGuru 9y agoJoins will use the regular index matching it against the join condition just like a where clause would.
- branko_d 9y agoForeign keys can improve performance, in some cases: https://stackoverflow.com/a/8154375/533120 https://stackoverflow.com/a/8154375/533120