diff options
Diffstat (limited to 'doc/src/sgml/man7/CREATE_COLLATION.7')
| -rw-r--r-- | doc/src/sgml/man7/CREATE_COLLATION.7 | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/doc/src/sgml/man7/CREATE_COLLATION.7 b/doc/src/sgml/man7/CREATE_COLLATION.7 new file mode 100644 index 0000000..4ac6130 --- /dev/null +++ b/doc/src/sgml/man7/CREATE_COLLATION.7 @@ -0,0 +1,197 @@ +'\" t +.\" Title: CREATE COLLATION +.\" Author: The PostgreSQL Global Development Group +.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/> +.\" Date: 2021 +.\" Manual: PostgreSQL 13.4 Documentation +.\" Source: PostgreSQL 13.4 +.\" Language: English +.\" +.TH "CREATE COLLATION" "7" "2021" "PostgreSQL 13.4" "PostgreSQL 13.4 Documentation" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +CREATE_COLLATION \- define a new collation +.SH "SYNOPSIS" +.sp +.nf +CREATE COLLATION [ IF NOT EXISTS ] \fIname\fR ( + [ LOCALE = \fIlocale\fR, ] + [ LC_COLLATE = \fIlc_collate\fR, ] + [ LC_CTYPE = \fIlc_ctype\fR, ] + [ PROVIDER = \fIprovider\fR, ] + [ DETERMINISTIC = \fIboolean\fR, ] + [ VERSION = \fIversion\fR ] +) +CREATE COLLATION [ IF NOT EXISTS ] \fIname\fR FROM \fIexisting_collation\fR +.fi +.SH "DESCRIPTION" +.PP +\fBCREATE COLLATION\fR +defines a new collation using the specified operating system locale settings, or by copying an existing collation\&. +.PP +To be able to create a collation, you must have +CREATE +privilege on the destination schema\&. +.SH "PARAMETERS" +.PP +IF NOT EXISTS +.RS 4 +Do not throw an error if a collation with the same name already exists\&. A notice is issued in this case\&. Note that there is no guarantee that the existing collation is anything like the one that would have been created\&. +.RE +.PP +\fIname\fR +.RS 4 +The name of the collation\&. The collation name can be schema\-qualified\&. If it is not, the collation is defined in the current schema\&. The collation name must be unique within that schema\&. (The system catalogs can contain collations with the same name for other encodings, but these are ignored if the database encoding does not match\&.) +.RE +.PP +\fIlocale\fR +.RS 4 +This is a shortcut for setting +LC_COLLATE +and +LC_CTYPE +at once\&. If you specify this, you cannot specify either of those parameters\&. +.RE +.PP +\fIlc_collate\fR +.RS 4 +Use the specified operating system locale for the +LC_COLLATE +locale category\&. +.RE +.PP +\fIlc_ctype\fR +.RS 4 +Use the specified operating system locale for the +LC_CTYPE +locale category\&. +.RE +.PP +\fIprovider\fR +.RS 4 +Specifies the provider to use for locale services associated with this collation\&. Possible values are: +icu, +libc\&. +libc +is the default\&. The available choices depend on the operating system and build options\&. +.RE +.PP +DETERMINISTIC +.RS 4 +Specifies whether the collation should use deterministic comparisons\&. The default is true\&. A deterministic comparison considers strings that are not byte\-wise equal to be unequal even if they are considered logically equal by the comparison\&. PostgreSQL breaks ties using a byte\-wise comparison\&. Comparison that is not deterministic can make the collation be, say, case\- or accent\-insensitive\&. For that, you need to choose an appropriate +LC_COLLATE +setting +\fIand\fR +set the collation to not deterministic here\&. +.sp +Nondeterministic collations are only supported with the ICU provider\&. +.RE +.PP +\fIversion\fR +.RS 4 +Specifies the version string to store with the collation\&. Normally, this should be omitted, which will cause the version to be computed from the actual version of the collation as provided by the operating system\&. This option is intended to be used by +\fBpg_upgrade\fR +for copying the version from an existing installation\&. +.sp +See also +ALTER COLLATION (\fBALTER_COLLATION\fR(7)) +for how to handle collation version mismatches\&. +.RE +.PP +\fIexisting_collation\fR +.RS 4 +The name of an existing collation to copy\&. The new collation will have the same properties as the existing one, but it will be an independent object\&. +.RE +.SH "NOTES" +.PP +\fBCREATE COLLATION\fR +takes a +SHARE ROW EXCLUSIVE +lock, which is self\-conflicting, on the +pg_collation +system catalog, so only one +\fBCREATE COLLATION\fR +command can run at a time\&. +.PP +Use +\fBDROP COLLATION\fR +to remove user\-defined collations\&. +.PP +See +Section\ \&23.2.2.3 +for more information on how to create collations\&. +.PP +When using the +libc +collation provider, the locale must be applicable to the current database encoding\&. See +CREATE DATABASE (\fBCREATE_DATABASE\fR(7)) +for the precise rules\&. +.SH "EXAMPLES" +.PP +To create a collation from the operating system locale +fr_FR\&.utf8 +(assuming the current database encoding is +UTF8): +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE COLLATION french (locale = \*(Aqfr_FR\&.utf8\*(Aq); +.fi +.if n \{\ +.RE +.\} +.PP +To create a collation using the ICU provider using German phone book sort order: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE COLLATION german_phonebook (provider = icu, locale = \*(Aqde\-u\-co\-phonebk\*(Aq); +.fi +.if n \{\ +.RE +.\} +.PP +To create a collation from an existing collation: +.sp +.if n \{\ +.RS 4 +.\} +.nf +CREATE COLLATION german FROM "de_DE"; +.fi +.if n \{\ +.RE +.\} +.sp +This can be convenient to be able to use operating\-system\-independent collation names in applications\&. +.SH "COMPATIBILITY" +.PP +There is a +\fBCREATE COLLATION\fR +statement in the SQL standard, but it is limited to copying an existing collation\&. The syntax to create a new collation is a +PostgreSQL +extension\&. +.SH "SEE ALSO" +ALTER COLLATION (\fBALTER_COLLATION\fR(7)), DROP COLLATION (\fBDROP_COLLATION\fR(7)) |