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POSIX

standard POSIX collation

Reading PostgreSQL 18.6.

Description

standard POSIX collation

Collisdeterministic: t
Collcollate: POSIX
Collctype: POSIX
Colllocale: _null_
Collicurules: _null_
Collversion: _null_
Collname: POSIX
Collprovider: c
Collencoding: -1

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 encoding UTF8. (This collation has the same behavior as the libc locale specification C in UTF8 encoding.)
pg_unicode_fast: This collation sorts by Unicode code point values rather than natural language order. For the functions lower, initcap, and upper it 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 encoding UTF8.
pg_c_utf8: This collation sorts by Unicode code point values rather than natural language order. For the functions lower, initcap, and upper, 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 encoding UTF8.
C (equivalent to POSIX): The C and POSIX collations 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 default collation 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

libc provider

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 11 → 12: changed.

--- PostgreSQL 11
+++ PostgreSQL 12
@@ -2,6 +2,7 @@
   "collcollate": "POSIX",
   "collctype": "POSIX",
   "collencoding": "-1",
+  "collisdeterministic": "t",
   "collname": "POSIX",
   "collprovider": "c"
 }

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 10 through 20; the first sample is not necessarily its introduction.