9.14. UUID Functions
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## 9.14. UUID Functions #

PostgreSQL includes one function to generate a UUID:

    gen_random_uuid () → uuid

This function returns a version 4 (random) UUID. This is the most commonly used type of UUID and is appropriate for most applications.

The uuid-ossp module provides additional functions that implement other standard algorithms for generating UUIDs.

There are also functions to extract data from UUIDs:

    uuid_extract_timestamp (uuid) → timestamp with time zone

This function extracts a `timestamp with time zone` from UUID version 1. For other versions, this function returns null. Note that the extracted timestamp is not necessarily exactly equal to the time the UUID was generated; this depends on the implementation that generated the UUID.

    uuid_extract_version (uuid) → smallint

This function extracts the version from a UUID of the variant described by RFC 4122. For other variants, this function returns null. For example, for a UUID generated by `gen_random_uuid`, this function will return 4.

PostgreSQL also provides the usual comparison operators shown in Table 9.1 for UUIDs.

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