PostgreSQL UUID Types and Functions

1. What is UUID data type in PostgreSQL?
2. What is the use of UUID in PostgreSQL?
3. What type is UUID?
4. Can Postgres generate UUID?
5. What is UUID in database?
6. Are UUID really unique?
7. How is UUID stored in Postgres?
8. What are UUIDs used for?
9. What is UUID OSSP?
10. Which version of UUID should I use?
11. How do I get UUID?
12. What is the difference between UUID and GUID?

What is UUID data type in PostgreSQL?

8.12. UUID Type. The data type uuid stores Universally Unique Identifiers (UUID) as defined by RFC 4122, ISO/IEC 9834-8:2005, and related standards. (Some systems refer to this data type as a globally unique identifier, or GUID, instead.)

What is the use of UUID in PostgreSQL?

PostgreSQL has its own UUID data type and provides modules to generate them. UUID is generally used in distributed systems as it guarantees a singularity better than the SERIAL data type which produces only singular values within a sole database.

What type is UUID?

A universally unique identifier (UUID) is a 128-bit label used for information in computer systems. The term globally unique identifier (GUID) is also used, often in software created by Microsoft.

Can Postgres generate UUID?

Generating UUID values

PostgreSQL allows you store and compare UUID values but it does not include functions for generating the UUID values in its core. Instead, it relies on the third-party modules that provide specific algorithms to generate UUIDs.

What is UUID in database?

UUID stands for Universally Unique IDentifier. UUID is defined based on RFC 4122, “a Universally Unique Identifier (UUID) URN Namespace). UUID is designed as a number that is unique globally in space and time. Two UUID values are expected to be distinct, even they are generated on two independent servers.

Are UUID really unique?

No, a UUID can't be guaranteed to be unique. A UUID is just a 128-bit random number. When my computer generates a UUID, there's no practical way it can prevent your computer or any other device in the universe from generating that same UUID at some time in the future.

How is UUID stored in Postgres?

The GUID/UUID is not a text in either PostgreSQL or SQL Server system. They are native typs in both systems and are stored using 16 bytes. PostgreSQL does although have auto casts built in for converting uuids to text where as SQL Server requires an explicit cast to varchar.

What are UUIDs used for?

UUIDs are generally used for identifying information that needs to be unique within a system or network thereof. Their uniqueness and low probability in being repeated makes them useful for being associative keys in databases and identifiers for physical hardware within an organization.

What is UUID OSSP?

The uuid-ossp module provides functions to generate universally unique identifiers (UUIDs) using one of several standard algorithms. There are also functions to produce certain special UUID constants.

Which version of UUID should I use?

If you need to always generate the same UUID from a given name, you want a version 3 or version 5. Version 3: This generates a unique ID from an MD5 hash of a namespace and name. If you need backwards compatibility (with another system that generates UUIDs from names), use this.

How do I get UUID?

The procedure to generate a version 4 UUID is as follows:

1. Generate 16 random bytes (=128 bits)
2. Adjust certain bits according to RFC 4122 section 4.4 as follows: ...
3. Encode the adjusted bytes as 32 hexadecimal digits.
4. Add four hyphen "-" characters to obtain blocks of 8, 4, 4, 4 and 12 hex digits.

What is the difference between UUID and GUID?

The GUID designation is an industry standard defined by Microsoft to provide a reference number which is unique in any context. UUID is a term that stands for Universal Unique Identifier. Similarly, GUID stands for Globally Unique Identifier. So basically, two terms for the same thing.