Wiki / Collations & Encodings / Bootstrap collations
pg_c_utf8
sorts by Unicode code point; Unicode and POSIX character semantics
Reading PostgreSQL 18.6.
Description
sorts by Unicode code point; Unicode and POSIX character semantics
- Collisdeterministic
- t
- Collcollate
- _null_
- Collctype
- _null_
- Colllocale
- C.UTF-8
- Collicurules
- _null_
- Collversion
- 1
- Collname
- pg_c_utf8
- Collprovider
- b
- Collencoding
- 6
Manual definition
23.2.2.1. Standard Collations
On all platforms, the following collations are supported:
unicode-
This SQL standard collation sorts using the Unicode Collation Algorithm with the Default Unicode Collation Element Table. It is available in all encodings. ICU support is required to use this collation, and behavior may change if PostgreSQL is built with a different version of ICU. (This collation has the same behavior as the ICU root locale; see
und-x-icu(for “undefined”).) ucs_basic-
This SQL standard collation sorts using the Unicode code point values rather than natural language order, and only the ASCII letters “
A” through “Z” are treated as letters. The behavior is efficient and stable across all versions. Only available for encodingUTF8. (This collation has the same behavior as the libc locale specificationCinUTF8encoding.) pg_unicode_fast-
This collation sorts by Unicode code point values rather than natural language order. For the functions
lower,initcap, andupperit uses Unicode full case mapping. For pattern matching (including regular expressions), it uses the Standard variant of Unicode Compatibility Properties. Behavior is efficient and stable within a Postgres major version. It is only available for encodingUTF8. pg_c_utf8-
This collation sorts by Unicode code point values rather than natural language order. For the functions
lower,initcap, andupper, it uses Unicode simple case mapping. For pattern matching (including regular expressions), it uses the POSIX Compatible variant of Unicode Compatibility Properties. Behavior is efficient and stable within a PostgreSQL major version. This collation is only available for encodingUTF8. C(equivalent toPOSIX)-
The
CandPOSIXcollations are based on “traditional C” behavior. They sort by byte values rather than natural language order, and only the ASCII letters “A” through “Z” are treated as letters. The behavior is efficient and stable across all versions for a given database encoding, but behavior may vary between different database encodings. default-
The
defaultcollation selects the locale specified at database creation time.
Additional collations may be available depending on operating system support. The efficiency and stability of these additional collations depend on the collation provider, the provider version, and the locale.
Related entries
Documentation and source
Source build
- Version
- 18.6
- Build
- https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2
- Source fingerprint
555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f
Compare versions
PostgreSQL 16 → 17: added.
--- PostgreSQL 16
+++ PostgreSQL 17
@@ -1 +1,8 @@
-Not recorded in this version
+{
+ "collencoding": "6",
+ "collisdeterministic": "t",
+ "collname": "pg_c_utf8",
+ "collprovider": "b",
+ "collversion": "1",
+ "locale": "C.UTF-8"
+}Compares recorded interfaces and attributes. Source fingerprints and build metadata are excluded; an absent sample is not proof of the introduction or removal release.
Related entries
Export JSON · Back to Collations & Encodings · Recorded in PostgreSQL 17 through 20; the first sample is not necessarily its introduction.