Nikolay and Michael discuss adding constraints in an online fashion, using NOT VALID and then VALIDATE CONSTRAINT.
 
Here are some links to things they mentioned:

• ADD table_constraint NOT VALID  https://www.postgresql.org/docs/current/sql-altertable.html#SQL-ALTERTABLE-DESC-ADD-TABLE-CONSTRAINT
• Our episode on zero-downtime migrations https://postgres.fm/episodes/zero-downtime-migrations
• VALIDATE CONSTRAINT https://www.postgresql.org/docs/current/sql-altertable.html#SQL-ALTERTABLE-DESC-VALIDATE-CONSTRAINT
• ALTER TABLE notes https://www.postgresql.org/docs/current/sql-altertable.html#SQL-ALTERTABLE-NOTES
• pgroll https://github.com/xataio/pgroll

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What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

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Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With special thanks to:

• Jessie Draws for the elephant artwork