3.13. Collations

Collations are objects that allow for the sorting mode and character classification behavior to be specified either per column or per operation. Collations can be used to override the way data is sorted in a database, even if the database has its modes defined by LC_COLLATE and LC_CTYPE attributes.

1

General
#	Field	Description
1	Collation	An existing collation from which the new collation is created (FROM). Selecting it clears the fields Locale, LC_COLLATE, and LC_CTYPE.

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Attributes
#	Field	Group box	Description
1	Locale	Basics	A shortcut to specify the attributes LC_COLLATE and LC_CTYPE at once (LOCALE). Filling it clears the base collation and the fields of the groups LC_COLLATE and LC_CTYPE.
2	Encoding	Basics	The character set (encoding) in which the collation works.
3	Modifier	Basics	Present in the groups Basics, LC_COLLATE, and LC_CTYPE, this field can be used to provide extra modifiers (like a custom currency code) to the locale. The modifier is any value specified after the character @.
4	Provider	Basics	The provider that supplies the locale services associated with the collation: libc or icu. Default leaves the choice to PostgreSQL.
5	Deterministic	Basics	Indicates that the collation is deterministic. A deterministic collation considers strings that are not byte-wise equal to be unequal, even if the comparison considers them logically equal.
6	Language	LC_COLLATE	The language (locale) used for string sorting (LC_COLLATE). The values listed are platform-dependent; leave it as Not defined if unsure. You can type a value that isn't listed. Selecting a value clears the base collation and Locale.
7	Language	LC_CTYPE	The language (locale) used for character classification, such as upper, lower, and digit (LC_CTYPE). The values listed are platform-dependent; leave it as Not defined if unsure. You can type a value that isn't listed. Selecting a value clears the base collation and Locale.
8	Modifier	LC_COLLATE	The modifier is any value specified after the character @. For example: en_US.utf8@modifier
9	Modifier	LC_CTYPE	The modifier is any value specified after the character @. For example: en_US.utf8@modifier

note

Note: The attributes Collation, Locale, LC_COLLATE, and LC_CTYPE are mutually exclusive: you can use only one of them at a time.

References

Collation DDL
https://www.postgresql.org/docs/current/static/sql-createcollation.html