Should we use foreign keys?

Nikolay and Michael discuss foreign keys in Postgres — what they are, their benefits, their overhead, some edge cases to be aware of, some improvements coming, and whether or not they generally recommend using them.
 
Here are some links to things they mentioned:

• Foreign keys (docs) https://www.postgresql.org/docs/current/ddl-constraints.html#DDL-CONSTRAINTS-FK
• Our episode about constraints: https://postgres.fm/episodes/constraints
• GitLab migration helper add_concurrent_foreign_key https://github.com/gitlabhq/gitlabhq/blob/master/rubocop/cop/migration/add_concurrent_foreign_key.rb
• Adding a foreign key without downtime (tweet by Nikolay) https://x.com/samokhvalov/status/1732056107483636188
• Bloat, pg_repack, and deferred constraints (blog post by Miro) https://medium.com/miro-engineering/postgresql-bloat-pg-repack-and-deferred-constraints-d0ecf33337ec
• Postgres 17 draft …

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