![]() ![]() The ULID spec links to implementations in different languages, but none for PostGres currently exists. The above lacks the version/variant required by RFC 4122, but PostGres will happily store it, as well as any ULID. ![]() ( KSUID is another option, though it's 20 bytes, so you'll need to make it a bytea.) PostGres doesn't require UUIDs to conform to the spec, so the following works: CREATE TABLE mytable ( ULID offers lexicographic sorting and is a "drop-in" replacement for UUIDs, being 16 bytes. NEWSEQUENTIALID doesn't conform to RFC 4122, so it sounds like you're willing to consider nonconforming UUID-esque "types". will create in my case: db=# select * from names Bush'),('Barack Obama'),('Donald Trump') Bush'),('William (Bill) Jefferson Clinton'),('George W. Ford'),('James (Jimmy) Earl Carter, Jr.'),('Ronald Wilson Reagan'),('George H. Hoover'),('Franklin Delano Roosevelt'),('Harry S Truman'),('Dwight David Eisenhower'),('John Fitzgerald Kennedy'),('Lyndon Baines Johnson'),('Richard Milhous Nixon'),('Gerald R. INSERT INTO names (name) VALUES ('William McKinley'),('Theodore Roosevelt'),('William Taft'),('Woodrow Wilson'),('Warren Harding'),('Calvin Coolidge'),('Herbert C. Make it work by example: DROP SEQUENCE IF EXISTS tablename_names_seq ĬREATE SEQUENCE tablename_names_seq AS integer ĬREATE TABLE names(id uuid NOT NULL DEFAULT uuid_sequence_nextval('tablename_names_seq'::regclass),name varchar(40)) Inside PostgreSQL: CREATE EXTENSION sequential-uuids Prerequires on Ubuntu: postgresql-server-dev-11 The wrapping eliminates the predictability." Instead of generating a perfectly sequential prefix, the value is sequential for a while, but also wraps around once in a while. Vondra's extension is using bits of both worlds: ". Using perfectly sequential UUID become predictable and works against the original idea of using UUID's in that they are globally unique. Primary key's are used by indexes to find data quicker as they are sequential so by using completely random UUID's they miss the advantage. Yes, Tomas Vondra created a sequential uuid extension for PostgreSQL based on the MSSQL newsequentialid only less predictable. Uuid_generate_v4() This function generates a version 4 UUID, which is derived entirely from random numbers. And to that I would use uuid_generate_v4() In fact, given the chance of fewer collisions and more security, I would take it. ![]() Postgres has no such concept, so I don't think that would make a difference in Postgres That all said, I agree with my understanding this is only necessary in SQL Server because tables are stored in a clustered index which makes random insertions slower then with a heap table. So long as the MAC address does not change, you'll be golden. Note that UUIDs of this kind reveal the identity of the computer that created the identifier and the time at which it did so, which might make it unsuitable for certain security-sensitive applications. This involves the MAC address of the computer and a time stamp. Uuid_generate_v1() This function generates a version 1 UUID. There are also functions to produce certain special UUID constants. The uuid-ossp module provides functions to generate universally unique identifiers (UUIDs) using one of several standard algorithms. PostgreSQL uses the standardized UUID generation algorithms provided by ITU-T Rec. ![]()
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