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Specific Attributes

The CREATE COLLATION statement can also include specific attributes to configure the collation.The available specific attributes are listed in the table below.Not all specific attributes apply to every collation.If the attribute is not applicable to the collation, but is specified when creating it, it will not cause an error.

Important

Specific attribute names are case-sensitive.

In the table, “1 bpc” indicates that an attribute is valid for collations of character sets using 1 byte per character (so-called narrow character sets), and “UNI” for “Unicode collations”.

Table 1. Specific Collation Attributes
Atrribute Values Valid for Comment

DISABLE-COMPRESSIONS

0, 1

1 bpc, UNI

Disables compressions (a.k.a. contractions).Compressions cause certain character sequences to be sorted as atomic units, e.g. Spanish c+h as a single character ch

DISABLE-EXPANSIONS

0, 1

1 bpc

Disables expansions.Expansions cause certain characters (e.g. ligatures or umlauted vowels) to be treated as character sequences and sorted accordingly

ICU-VERSION

default or M.m

UNI

Specifies the ICU library version to use.Valid values are the ones defined in the applicable <intl_module> element in intl/fbintl.conf.Format: either the string literal “default” or a major+minor version number like “3.0” (both unquoted).

LOCALE

xx_YY

UNI

Specifies the collation locale.Requires complete version of ICU libraries.Format: a locale string like “du_NL” (unquoted)

MULTI-LEVEL

0, 1

1 bpc

Uses more than one ordering level

NUMERIC-SORT

0, 1

UNI

Treats contiguous groups of decimal digits in the string as atomic units and sorts them numerically.(This is also known as natural sorting)

SPECIALS-FIRST

0, 1

1 bpc

Orders special characters (spaces, symbols etc.) before alphanumeric characters
Tip

If you want to add a new character set with its default collation into your database, declare and run the stored procedure sp_register_character_set(name, max_bytes_per_character), found in misc/intl.sql under the Firebird installation directory.

In order for this to work, the character set must be present on the system and registered in a .conf file in the intl subdirectory.

Who Can Create a Collation

The CREATE COLLATION statement can be executed by:

The user executing the CREATE COLLATION statement becomes the owner of the collation.