Thiemo Kellner <thiemo@xxxxxxxxxxxxxxxxxxxx> writes: > I consider using uuid as primary key type. The documentation of > uuid-ossp states > (https://www.postgresql.org/docs/10/static/uuid-ossp.html#idm46428633607040) > makes a note to consider the pgcrypto function instead but not why. > Can somebody shed some light on that matter? I believe the point of the recommendation is that if you only need type-4 UUIDs, you can get that from pgcrypto without needing the external dependency of the OSSP UUID library. This is a bit less urgent than when that text was written, because now we also support building that contrib module against some other implementations; but there are still going to be systems on which installing uuid-ossp is inconvenient. There may also be a belief that pgcrypto's result is more cryptographically secure, though I wouldn't swear to that. regards, tom lane
