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(Some systems refer to this data type as a globally unique identifier, or GUID, instead.) This identifier is a 128-bit quantity that is generated by an algorithm chosen to make it very unlikely that the same identifier will be generated by anyone else in the known universe using the same algorithm. Therefore, for distributed systems, these identifiers provide a better uniqueness guarantee than sequence generators, which are only unique within a single database.\u003c/p\u003e\n\u003cp\u003eRFC 9562 defines 8 different UUID versions. Each version has specific requirements for generating new UUID values, and each version provides distinct benefits and drawbacks. \u003cspan class=\"productname\"\u003ePostgreSQL\u003c/span\u003e provides native support for generating UUIDs using the UUIDv4 and UUIDv7 algorithms. Alternatively, UUID values can be generated outside of the database using any algorithm. The data type \u003ccode class=\"type\"\u003euuid\u003c/code\u003e can be used to store any UUID, regardless of the origin and the UUID version.\u003c/p\u003e\n\u003cp\u003eA UUID is written as a sequence of lower-case hexadecimal digits, in several groups separated by hyphens, specifically a group of 8 digits followed by three groups of 4 digits followed by a group of 12 digits, for a total of 32 digits representing the 128 bits. An example of a UUID in this standard form is:\u003c/p\u003e\n\u003cpre class=\"programlisting\"\u003ea0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11\n\u003c/pre\u003e\n\u003cp\u003e\u003cspan class=\"productname\"\u003ePostgreSQL\u003c/span\u003e also accepts the following alternative forms for input: use of upper-case digits, the standard format surrounded by braces, omitting some or all hyphens, adding a hyphen after any group of four digits. 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related standards. (Some systems refer to this data type as a globally unique identifier, or GUID, instead.) This identifier is a 128-bit quantity that is generated by an algorithm chosen to make it very unlikely that the same identifier will be generated by anyone else in the known universe using the same algorithm. Therefore, for distributed systems, these identifiers provide a better uniqueness guarantee than sequence generators, which are only unique within a single database.\u003c/p\u003e\n\u003cp\u003eRFC 9562 defines 8 different UUID versions. Each version has specific requirements for generating new UUID values, and each version provides distinct benefits and drawbacks. \u003cspan\u003ePostgreSQL\u003c/span\u003e provides native support for generating UUIDs using the UUIDv4 and UUIDv7 algorithms. Alternatively, UUID values can be generated outside of the database using any algorithm. The data type \u003ccode\u003euuid\u003c/code\u003e can be used to store any UUID, regardless of the origin and the UUID version.\u003c/p\u003e\n\u003cp\u003eA UUID is written as a sequence of lower-case hexadecimal digits, in several groups separated by hyphens, specifically a group of 8 digits followed by three groups of 4 digits followed by a group of 12 digits, for a total of 32 digits representing the 128 bits. An example of a UUID in this standard form is:\u003c/p\u003e\n\u003cpre\u003ea0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11\n\u003c/pre\u003e\n\u003cp\u003e\u003cspan\u003ePostgreSQL\u003c/span\u003e also accepts the following alternative forms for input: use of upper-case digits, the standard format surrounded by braces, omitting some or all hyphens, adding a hyphen after any group of four digits. Examples are:\u003c/p\u003e\n\u003cpre\u003eA0EEBC99-9C0B-4EF8-BB6D-6BB9BD380A11\n{a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11}\na0eebc999c0b4ef8bb6d6bb9bd380a11\na0ee-bc99-9c0b-4ef8-bb6d-6bb9-bd38-0a11\n{a0eebc99-9c0b4ef8-bb6d6bb9-bd380a11}\n\u003c/pre\u003e\n\u003cp\u003eOutput is always in the standard form.\u003c/p\u003e\n\u003cp\u003eSee \u003ca href=\"/docs/18/functions-uuid.html\" rel=\"nofollow\"\u003eSection 9.14\u003c/a\u003e for how to generate a UUID in \u003cspan\u003ePostgreSQL\u003c/span\u003e.\u003c/p\u003e\n\u003c/div\u003e","SourceRevision":"555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f","ContentHash":"017741deaf5ed2b6bbc2f67e73cc618a9dae86007ec65885738abae2e89e2f4c","Payload":{"description":["universally unique identifier"],"manual_html":"\u003cdiv class=\"sect1\" id=\"DATATYPE-UUID\"\u003e\n\u003cdiv class=\"titlepage\"\u003e\n\u003cdiv\u003e\n\u003cdiv\u003e\n\u003ch2 class=\"title\"\u003e8.12. UUID Type \u003c/h2\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003eThe data type \u003ccode class=\"type\"\u003euuid\u003c/code\u003e stores Universally Unique Identifiers (UUID) as defined by \u003ca class=\"ulink\" href=\"https://datatracker.ietf.org/doc/html/rfc9562\"\u003eRFC 9562\u003c/a\u003e, ISO/IEC 9834-8:2005, and related standards. (Some systems refer to this data type as a globally unique identifier, or GUID, instead.) This identifier is a 128-bit quantity that is generated by an algorithm chosen to make it very unlikely that the same identifier will be generated by anyone else in the known universe using the same algorithm. Therefore, for distributed systems, these identifiers provide a better uniqueness guarantee than sequence generators, which are only unique within a single database.\u003c/p\u003e\n\u003cp\u003eRFC 9562 defines 8 different UUID versions. Each version has specific requirements for generating new UUID values, and each version provides distinct benefits and drawbacks. \u003cspan class=\"productname\"\u003ePostgreSQL\u003c/span\u003e provides native support for generating UUIDs using the UUIDv4 and UUIDv7 algorithms. Alternatively, UUID values can be generated outside of the database using any algorithm. The data type \u003ccode class=\"type\"\u003euuid\u003c/code\u003e can be used to store any UUID, regardless of the origin and the UUID version.\u003c/p\u003e\n\u003cp\u003eA UUID is written as a sequence of lower-case hexadecimal digits, in several groups separated by hyphens, specifically a group of 8 digits followed by three groups of 4 digits followed by a group of 12 digits, for a total of 32 digits representing the 128 bits. An example of a UUID in this standard form is:\u003c/p\u003e\n\u003cpre class=\"programlisting\"\u003ea0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11\n\u003c/pre\u003e\n\u003cp\u003e\u003cspan class=\"productname\"\u003ePostgreSQL\u003c/span\u003e also accepts the following alternative forms for input: use of upper-case digits, the standard format surrounded by braces, omitting some or all hyphens, adding a hyphen after any group of four digits. Examples are:\u003c/p\u003e\n\u003cpre class=\"programlisting\"\u003eA0EEBC99-9C0B-4EF8-BB6D-6BB9BD380A11\n{a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11}\na0eebc999c0b4ef8bb6d6bb9bd380a11\na0ee-bc99-9c0b-4ef8-bb6d-6bb9-bd38-0a11\n{a0eebc99-9c0b4ef8-bb6d6bb9-bd380a11}\n\u003c/pre\u003e\n\u003cp\u003eOutput is always in the standard form.\u003c/p\u003e\n\u003cp\u003eSee \u003ca class=\"xref\" href=\"/docs/18/functions-uuid.html\" title=\"9.14. UUID Functions\"\u003eSection 9.14\u003c/a\u003e for how to generate a UUID in \u003cspan class=\"productname\"\u003ePostgreSQL\u003c/span\u003e.\u003c/p\u003e\n\u003c/div\u003e","related":[{"label":"pg_type catalog","url":"/wiki/catalog/pg_type/?v=18"},{"label":"pg_cast catalog","url":"/wiki/catalog/pg_cast/?v=18"},{"label":"pg_operator catalog","url":"/wiki/catalog/pg_operator/?v=18"},{"label":"pg_opclass catalog","url":"/wiki/catalog/pg_opclass/?v=18"},{"label":"Arrays","url":"/wiki/type/arrays/?v=18"},{"label":"brin index access method","url":"/wiki/indexam/brin/?v=18"},{"label":"btree index access method","url":"/wiki/indexam/btree/?v=18"},{"label":"hash index access method","url":"/wiki/indexam/hash/?v=18"}],"sections":[]}},"RequestedLocale":"zh-Hans","Fallback":true,"Versions":["10","11","12","13","14","15","16","17","18","19","20"],"Locales":["en"],"Signatures":null,"Spellings":null,"SQLState":null,"Evidence":null}