v5-0004-Introduce-collation-provider-none.patch

From a13a15988ab2e991e42569b8b1e0cd1d6e940baf Mon Sep 17 00:00:00 2001
From: Jeff Davis <jeff@j-davis.com>
Date: Mon, 1 May 2023 15:38:29 -0700
Subject: [PATCH v5 4/7] Introduce collation provider "none".

Provides locale-unaware semantics that are implemented as fast byte
operations in Postgres, independent of the operating system or any
provider libraries.

Equivalent (in semantics and implementation) to the libc provider with
locale "C", except that LC_COLLATE and LC_CTYPE can be set
independently.

Use provider "none" for built-in collation "ucs_basic" instead of
libc.
---
 doc/src/sgml/charset.sgml              | 87 +++++++++++++++++++++-----
 doc/src/sgml/ref/create_collation.sgml |  2 +-
 doc/src/sgml/ref/create_database.sgml  |  2 +-
 doc/src/sgml/ref/createdb.sgml         |  2 +-
 doc/src/sgml/ref/initdb.sgml           |  2 +-
 src/backend/catalog/pg_collation.c     |  7 ++-
 src/backend/commands/collationcmds.c   | 84 ++++++++++++++++++++-----
 src/backend/commands/dbcommands.c      | 69 +++++++++++++++++---
 src/backend/utils/adt/pg_locale.c      | 27 +++++++-
 src/backend/utils/init/postinit.c      | 10 ++-
 src/bin/initdb/initdb.c                | 33 +++++++++-
 src/bin/initdb/t/001_initdb.pl         | 29 +++++++++
 src/bin/pg_dump/pg_dump.c              |  8 ++-
 src/bin/pg_upgrade/t/002_pg_upgrade.pl | 18 +++++-
 src/bin/psql/describe.c                |  2 +-
 src/bin/scripts/createdb.c             |  2 +-
 src/bin/scripts/t/020_createdb.pl      | 29 +++++++++
 src/include/catalog/pg_collation.dat   |  3 +-
 src/include/catalog/pg_collation.h     |  3 +
 src/test/regress/expected/collate.out  | 10 ++-
 src/test/regress/sql/collate.sql       |  6 ++
 21 files changed, 372 insertions(+), 63 deletions(-)

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 6dd95b8966..de7c65ae35 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -342,22 +342,14 @@ initdb --locale=sv_SE
    <title>Locale Providers</title>
 
    <para>
-    <productname>PostgreSQL</productname> supports multiple <firstterm>locale
-    providers</firstterm>.  This specifies which library supplies the locale
-    data.  One standard provider name is <literal>libc</literal>, which uses
-    the locales provided by the operating system C library.  These are the
-    locales used by most tools provided by the operating system.  Another
-    provider is <literal>icu</literal>, which uses the external
-    ICU<indexterm><primary>ICU</primary></indexterm> library.  ICU locales can
-    only be used if support for ICU was configured when PostgreSQL was built.
+    A locale provider specifies which library defines the locale behavior for
+    collations and character classifications.
    </para>
 
    <para>
     The commands and tools that select the locale settings, as described
-    above, each have an option to select the locale provider.  The examples
-    shown earlier all use the <literal>libc</literal> provider, which is the
-    default.  Here is an example to initialize a database cluster using the
-    ICU provider:
+    above, each have an option to select the locale provider. Here is an
+    example to initialize a database cluster using the ICU provider:
 <programlisting>
 initdb --locale-provider=icu --icu-locale=en
 </programlisting>
@@ -370,12 +362,73 @@ initdb --locale-provider=icu --icu-locale=en
    </para>
 
    <para>
-    Which locale provider to use depends on individual requirements.  For most
-    basic uses, either provider will give adequate results.  For the libc
-    provider, it depends on what the operating system offers; some operating
-    systems are better than others.  For advanced uses, ICU offers more locale
-    variants and customization options.
+    Regardless of the locale provider, the operating system is still used to
+    provide some locale-aware behavior, such as messages (see <xref
+    linkend="guc-lc-messages"/>).
    </para>
+
+   <para>
+    The available locale providers are listed below.
+   </para>
+
+   <sect3 id="locale-provider-none">
+    <title>None</title>
+    <para>
+     The <literal>none</literal> provider uses simple built-in operations
+     which are not locale-aware.
+    </para>
+    <para>
+     The collation and character classification behavior is equivalent to
+     using the <literal>libc</literal> provider with locale
+     <literal>C</literal>, except that <literal>LC_COLLATE</literal> and
+     <literal>LC_CTYPE</literal> can be set independently.
+    </para>
+    <note>
+     <para>
+      When using the <literal>none</literal> locale provider, behavior may
+      depend on the database encoding.
+     </para>
+    </note>
+   </sect3>
+   <sect3 id="locale-provider-icu">
+    <title>ICU</title>
+    <para>
+     The <literal>icu</literal> provider uses the external
+     ICU<indexterm><primary>ICU</primary></indexterm>
+     library. <productname>PostgreSQL</productname> must have been configured
+     with support.
+    </para>
+    <para>
+     ICU provides collation and character classification behavior that is
+     independent of the operating system and database encoding, which is
+     preferable if you expect to transition to other platforms without any
+     change in results. <literal>LC_COLLATE</literal> and
+     <literal>LC_CTYPE</literal> can be set independently of the ICU locale.
+    </para>
+    <note>
+     <para>
+      For the ICU provider, results may depend on the version of the ICU
+      library used, as it is updated to reflect changes in natural language
+      over time.
+     </para>
+    </note>
+   </sect3>
+   <sect3 id="locale-provider-libc">
+    <title>libc</title>
+    <para>
+     The <literal>libc</literal> provider uses the operating system's C
+     library. The collation and character classification behavior is
+     controlled by the settings <literal>LC_COLLATE</literal> and
+     <literal>LC_CTYPE</literal>, so they cannot be set independently.
+    </para>
+    <note>
+     <para>
+      The same locale name may have different behavior on different platforms
+      when using the libc provider.
+     </para>
+    </note>
+   </sect3>
+
   </sect2>
 
   <sect2 id="locale-problems">
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index f6353da5c1..5489ae7413 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -120,7 +120,7 @@ CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replace
      <listitem>
       <para>
        Specifies the provider to use for locale services associated with this
-       collation.  Possible values are
+       collation.  Possible values are <literal>none</literal>,
        <literal>icu</literal><indexterm><primary>ICU</primary></indexterm>
        (if the server was built with ICU support) or <literal>libc</literal>.
        <literal>libc</literal> is the default.  See <xref
diff --git a/doc/src/sgml/ref/create_database.sgml b/doc/src/sgml/ref/create_database.sgml
index 13793bb6b7..60b9da0952 100644
--- a/doc/src/sgml/ref/create_database.sgml
+++ b/doc/src/sgml/ref/create_database.sgml
@@ -212,7 +212,7 @@ CREATE DATABASE <replaceable class="parameter">name</replaceable>
       <listitem>
        <para>
         Specifies the provider to use for the default collation in this
-        database.  Possible values are
+        database.  Possible values are <literal>none</literal>,
         <literal>icu</literal><indexterm><primary>ICU</primary></indexterm>
         (if the server was built with ICU support) or <literal>libc</literal>.
         By default, the provider is the same as that of the <xref
diff --git a/doc/src/sgml/ref/createdb.sgml b/doc/src/sgml/ref/createdb.sgml
index e23419ba6c..326a371d34 100644
--- a/doc/src/sgml/ref/createdb.sgml
+++ b/doc/src/sgml/ref/createdb.sgml
@@ -168,7 +168,7 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
-      <term><option>--locale-provider={<literal>libc</literal>|<literal>icu</literal>}</option></term>
+      <term><option>--locale-provider={<literal>none</literal>|<literal>libc</literal>|<literal>icu</literal>}</option></term>
       <listitem>
        <para>
         Specifies the locale provider for the database's default collation.
diff --git a/doc/src/sgml/ref/initdb.sgml b/doc/src/sgml/ref/initdb.sgml
index 87945b4b62..e604ab48b7 100644
--- a/doc/src/sgml/ref/initdb.sgml
+++ b/doc/src/sgml/ref/initdb.sgml
@@ -323,7 +323,7 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry id="app-initdb-option-locale-provider">
-      <term><option>--locale-provider={<literal>libc</literal>|<literal>icu</literal>}</option></term>
+      <term><option>--locale-provider={<literal>none</literal>|<literal>libc</literal>|<literal>icu</literal>}</option></term>
       <listitem>
        <para>
         This option sets the locale provider for databases created in the new
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index fd022e6fc2..86b6ba2375 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -68,7 +68,12 @@ CollationCreate(const char *collname, Oid collnamespace,
 	Assert(collname);
 	Assert(collnamespace);
 	Assert(collowner);
-	Assert((collcollate && collctype) || colliculocale);
+	Assert((collprovider == COLLPROVIDER_NONE &&
+			!collcollate && !collctype && !colliculocale) ||
+		   (collprovider == COLLPROVIDER_LIBC &&
+			 collcollate &&  collctype && !colliculocale) ||
+		   (collprovider == COLLPROVIDER_ICU &&
+			!collcollate && !collctype &&  colliculocale));
 
 	/*
 	 * Make sure there is no existing collation of same name & encoding.
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index a53700256b..267a551818 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -215,7 +215,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 
 		if (collproviderstr)
 		{
-			if (pg_strcasecmp(collproviderstr, "icu") == 0)
+			if (pg_strcasecmp(collproviderstr, "none") == 0)
+				collprovider = COLLPROVIDER_NONE;
+			else if (pg_strcasecmp(collproviderstr, "icu") == 0)
 				collprovider = COLLPROVIDER_ICU;
 			else if (pg_strcasecmp(collproviderstr, "libc") == 0)
 				collprovider = COLLPROVIDER_LIBC;
@@ -228,6 +230,13 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		else
 			collprovider = COLLPROVIDER_LIBC;
 
+		if (collprovider == COLLPROVIDER_NONE
+			&& (localeEl || lccollateEl || lcctypeEl))
+		{
+			ereport(ERROR,
+					(errmsg("collation provider \"none\" does not support LOCALE, LC_COLLATE, or LC_CTYPE")));
+		}
+
 		if (localeEl)
 		{
 			if (collprovider == COLLPROVIDER_LIBC)
@@ -317,7 +326,15 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		 */
 		collencoding = GetDatabaseEncoding();
 
-		if (collprovider == COLLPROVIDER_ICU)
+		if (collprovider == COLLPROVIDER_NONE)
+		{
+			/*
+			 * The "none" provider works with all encodings, so no checking is
+			 * required. NB: the behavior may be different for different
+			 * encodings, though.
+			 */
+		}
+		else if (collprovider == COLLPROVIDER_ICU)
 		{
 #ifdef USE_ICU
 			/*
@@ -343,7 +360,18 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	}
 
 	if (!collversion)
-		collversion = get_collation_actual_version(collprovider, collprovider == COLLPROVIDER_ICU ? colliculocale : collcollate);
+	{
+		char *locale;
+
+		if (collprovider == COLLPROVIDER_ICU)
+			locale = colliculocale;
+		else if (collprovider == COLLPROVIDER_LIBC)
+			locale = collcollate;
+		else
+			locale = NULL; /* COLLPROVIDER_NONE */
+
+		collversion = get_collation_actual_version(collprovider, locale);
+	}
 
 	newoid = CollationCreate(collName,
 							 collNamespace,
@@ -418,6 +446,7 @@ AlterCollation(AlterCollationStmt *stmt)
 	Form_pg_collation collForm;
 	Datum		datum;
 	bool		isnull;
+	char	   *locale;
 	char	   *oldversion;
 	char	   *newversion;
 	ObjectAddress address;
@@ -442,8 +471,20 @@ AlterCollation(AlterCollationStmt *stmt)
 	datum = SysCacheGetAttr(COLLOID, tup, Anum_pg_collation_collversion, &isnull);
 	oldversion = isnull ? NULL : TextDatumGetCString(datum);
 
-	datum = SysCacheGetAttrNotNull(COLLOID, tup, collForm->collprovider == COLLPROVIDER_ICU ? Anum_pg_collation_colliculocale : Anum_pg_collation_collcollate);
-	newversion = get_collation_actual_version(collForm->collprovider, TextDatumGetCString(datum));
+	if (collForm->collprovider == COLLPROVIDER_ICU)
+	{
+		datum = SysCacheGetAttrNotNull(COLLOID, tup, Anum_pg_collation_colliculocale);
+		locale = TextDatumGetCString(datum);
+	}
+	else if (collForm->collprovider == COLLPROVIDER_LIBC)
+	{
+		datum = SysCacheGetAttrNotNull(COLLOID, tup, Anum_pg_collation_collcollate);
+		locale = TextDatumGetCString(datum);
+	}
+	else
+		locale = NULL; /* COLLPROVIDER_NONE */
+
+	newversion = get_collation_actual_version(collForm->collprovider, locale);
 
 	/* cannot change from NULL to non-NULL or vice versa */
 	if ((!oldversion && newversion) || (oldversion && !newversion))
@@ -506,11 +547,18 @@ pg_collation_actual_version(PG_FUNCTION_ARGS)
 
 		provider = ((Form_pg_database) GETSTRUCT(dbtup))->datlocprovider;
 
-		datum = SysCacheGetAttrNotNull(DATABASEOID, dbtup,
-									   provider == COLLPROVIDER_ICU ?
-									   Anum_pg_database_daticulocale : Anum_pg_database_datcollate);
-
-		locale = TextDatumGetCString(datum);
+		if (provider == COLLPROVIDER_ICU)
+		{
+			datum = SysCacheGetAttrNotNull(DATABASEOID, dbtup, Anum_pg_database_daticulocale);
+			locale = TextDatumGetCString(datum);
+		}
+		else if (provider == COLLPROVIDER_LIBC)
+		{
+			datum = SysCacheGetAttrNotNull(DATABASEOID, dbtup, Anum_pg_database_datcollate);
+			locale = TextDatumGetCString(datum);
+		}
+		else
+			locale = NULL; /* COLLPROVIDER_NONE */
 
 		ReleaseSysCache(dbtup);
 	}
@@ -526,11 +574,19 @@ pg_collation_actual_version(PG_FUNCTION_ARGS)
 
 		provider = ((Form_pg_collation) GETSTRUCT(colltp))->collprovider;
 		Assert(provider != COLLPROVIDER_DEFAULT);
-		datum = SysCacheGetAttrNotNull(COLLOID, colltp,
-									   provider == COLLPROVIDER_ICU ?
-									   Anum_pg_collation_colliculocale : Anum_pg_collation_collcollate);
 
-		locale = TextDatumGetCString(datum);
+		if (provider == COLLPROVIDER_ICU)
+		{
+			datum = SysCacheGetAttrNotNull(COLLOID, colltp, Anum_pg_collation_colliculocale);
+			locale = TextDatumGetCString(datum);
+		}
+		else if (provider == COLLPROVIDER_LIBC)
+		{
+			datum = SysCacheGetAttrNotNull(COLLOID, colltp, Anum_pg_collation_collcollate);
+			locale = TextDatumGetCString(datum);
+		}
+		else
+			locale = NULL; /* COLLPROVIDER_NONE */
 
 		ReleaseSysCache(colltp);
 	}
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 2e242eeff2..9e73f54803 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -909,7 +909,9 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 	{
 		char	   *locproviderstr = defGetString(dlocprovider);
 
-		if (pg_strcasecmp(locproviderstr, "icu") == 0)
+		if (pg_strcasecmp(locproviderstr, "none") == 0)
+			dblocprovider = COLLPROVIDER_NONE;
+		else if (pg_strcasecmp(locproviderstr, "icu") == 0)
 			dblocprovider = COLLPROVIDER_ICU;
 		else if (pg_strcasecmp(locproviderstr, "libc") == 0)
 			dblocprovider = COLLPROVIDER_LIBC;
@@ -1177,9 +1179,17 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 	 */
 	if (src_collversion && !dcollversion)
 	{
-		char	   *actual_versionstr;
+		char	*actual_versionstr;
+		char	*locale;
 
-		actual_versionstr = get_collation_actual_version(dblocprovider, dblocprovider == COLLPROVIDER_ICU ? dbiculocale : dbcollate);
+		if (dblocprovider == COLLPROVIDER_ICU)
+			locale = dbiculocale;
+		else if (dblocprovider == COLLPROVIDER_LIBC)
+			locale = dbcollate;
+		else
+			locale = NULL; /* COLLPROVIDER_NONE */
+
+		actual_versionstr = get_collation_actual_version(dblocprovider, locale);
 		if (!actual_versionstr)
 			ereport(ERROR,
 					(errmsg("template database \"%s\" has a collation version, but no actual collation version could be determined",
@@ -1207,7 +1217,18 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 	 * collation version, which is normally only the case for template0.
 	 */
 	if (dbcollversion == NULL)
-		dbcollversion = get_collation_actual_version(dblocprovider, dblocprovider == COLLPROVIDER_ICU ? dbiculocale : dbcollate);
+	{
+		char *locale;
+
+		if (dblocprovider == COLLPROVIDER_ICU)
+			locale = dbiculocale;
+		else if (dblocprovider == COLLPROVIDER_LIBC)
+			locale = dbcollate;
+		else
+			locale = NULL; /* COLLPROVIDER_NONE */
+
+		dbcollversion = get_collation_actual_version(dblocprovider, locale);
+	}
 
 	/* Resolve default tablespace for new database */
 	if (dtablespacename && dtablespacename->arg)
@@ -2403,6 +2424,7 @@ AlterDatabaseRefreshColl(AlterDatabaseRefreshCollStmt *stmt)
 	ObjectAddress address;
 	Datum		datum;
 	bool		isnull;
+	char	   *locale;
 	char	   *oldversion;
 	char	   *newversion;
 
@@ -2429,10 +2451,24 @@ AlterDatabaseRefreshColl(AlterDatabaseRefreshCollStmt *stmt)
 	datum = heap_getattr(tuple, Anum_pg_database_datcollversion, RelationGetDescr(rel), &isnull);
 	oldversion = isnull ? NULL : TextDatumGetCString(datum);
 
-	datum = heap_getattr(tuple, datForm->datlocprovider == COLLPROVIDER_ICU ? Anum_pg_database_daticulocale : Anum_pg_database_datcollate, RelationGetDescr(rel), &isnull);
-	if (isnull)
-		elog(ERROR, "unexpected null in pg_database");
-	newversion = get_collation_actual_version(datForm->datlocprovider, TextDatumGetCString(datum));
+	if (datForm->datlocprovider == COLLPROVIDER_ICU)
+	{
+		datum = heap_getattr(tuple, Anum_pg_database_daticulocale, RelationGetDescr(rel), &isnull);
+		if (isnull)
+			elog(ERROR, "unexpected null in pg_database");
+		locale = TextDatumGetCString(datum);
+	}
+	else if (datForm->datlocprovider == COLLPROVIDER_LIBC)
+	{
+		datum = heap_getattr(tuple, Anum_pg_database_datcollate, RelationGetDescr(rel), &isnull);
+		if (isnull)
+			elog(ERROR, "unexpected null in pg_database");
+		locale = TextDatumGetCString(datum);
+	}
+	else
+		locale = NULL; /* COLLPROVIDER_NONE */
+
+	newversion = get_collation_actual_version(datForm->datlocprovider, locale);
 
 	/* cannot change from NULL to non-NULL or vice versa */
 	if ((!oldversion && newversion) || (oldversion && !newversion))
@@ -2617,6 +2653,7 @@ pg_database_collation_actual_version(PG_FUNCTION_ARGS)
 	HeapTuple	tp;
 	char		datlocprovider;
 	Datum		datum;
+	char	   *locale;
 	char	   *version;
 
 	tp = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(dbid));
@@ -2627,8 +2664,20 @@ pg_database_collation_actual_version(PG_FUNCTION_ARGS)
 
 	datlocprovider = ((Form_pg_database) GETSTRUCT(tp))->datlocprovider;
 
-	datum = SysCacheGetAttrNotNull(DATABASEOID, tp, datlocprovider == COLLPROVIDER_ICU ? Anum_pg_database_daticulocale : Anum_pg_database_datcollate);
-	version = get_collation_actual_version(datlocprovider, TextDatumGetCString(datum));
+	if (datlocprovider == COLLPROVIDER_ICU)
+	{
+		datum = SysCacheGetAttrNotNull(DATABASEOID, tp, Anum_pg_database_daticulocale);
+		locale = TextDatumGetCString(datum);
+	}
+	else if (datlocprovider == COLLPROVIDER_LIBC)
+	{
+		datum = SysCacheGetAttrNotNull(DATABASEOID, tp, Anum_pg_database_datcollate);
+		locale = TextDatumGetCString(datum);
+	}
+	else
+		locale = NULL; /* COLLPROVIDER_NONE */
+
+	version = get_collation_actual_version(datlocprovider, locale);
 
 	ReleaseSysCache(tp);
 
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index bb4a8d84f6..5ac5036f05 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1228,7 +1228,12 @@ lookup_collation_cache(Oid collation, bool set_flags)
 			elog(ERROR, "cache lookup failed for collation %u", collation);
 		collform = (Form_pg_collation) GETSTRUCT(tp);
 
-		if (collform->collprovider == COLLPROVIDER_LIBC)
+		if (collform->collprovider == COLLPROVIDER_NONE)
+		{
+			cache_entry->collate_is_c = true;
+			cache_entry->ctype_is_c = true;
+		}
+		else if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
 			Datum		datum;
 			const char *collcollate;
@@ -1281,6 +1286,9 @@ lc_collate_is_c(Oid collation)
 		static int	result = -1;
 		char	   *localeptr;
 
+		if (default_locale.provider == COLLPROVIDER_NONE)
+			return true;
+
 		if (default_locale.provider == COLLPROVIDER_ICU)
 			return false;
 
@@ -1334,6 +1342,9 @@ lc_ctype_is_c(Oid collation)
 		static int	result = -1;
 		char	   *localeptr;
 
+		if (default_locale.provider == COLLPROVIDER_NONE)
+			return true;
+
 		if (default_locale.provider == COLLPROVIDER_ICU)
 			return false;
 
@@ -1487,8 +1498,10 @@ pg_newlocale_from_collation(Oid collid)
 	{
 		if (default_locale.provider == COLLPROVIDER_ICU)
 			return &default_locale;
-		else
+		else if (default_locale.provider == COLLPROVIDER_LIBC)
 			return (pg_locale_t) 0;
+		else
+			elog(ERROR, "cannot open collation with provider \"none\"");
 	}
 
 	cache_entry = lookup_collation_cache(collid, false);
@@ -1513,7 +1526,11 @@ pg_newlocale_from_collation(Oid collid)
 		result.provider = collform->collprovider;
 		result.deterministic = collform->collisdeterministic;
 
-		if (collform->collprovider == COLLPROVIDER_LIBC)
+		if (collform->collprovider == COLLPROVIDER_NONE)
+		{
+			elog(ERROR, "cannot open collation with provider \"none\"");
+		}
+		else if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
 #ifdef HAVE_LOCALE_T
 			const char *collcollate;
@@ -1599,6 +1616,7 @@ pg_newlocale_from_collation(Oid collid)
 
 			collversionstr = TextDatumGetCString(datum);
 
+			Assert(collform->collprovider != COLLPROVIDER_NONE);
 			datum = SysCacheGetAttrNotNull(COLLOID, tp, collform->collprovider == COLLPROVIDER_ICU ? Anum_pg_collation_colliculocale : Anum_pg_collation_collcollate);
 
 			actual_versionstr = get_collation_actual_version(collform->collprovider,
@@ -1650,6 +1668,9 @@ get_collation_actual_version(char collprovider, const char *collcollate)
 {
 	char	   *collversion = NULL;
 
+	if (collprovider == COLLPROVIDER_NONE)
+		return NULL;
+
 #ifdef USE_ICU
 	if (collprovider == COLLPROVIDER_ICU)
 	{
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 53420f4974..8053642fd3 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -461,10 +461,18 @@ CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connect
 	{
 		char	   *actual_versionstr;
 		char	   *collversionstr;
+		char	   *locale;
 
 		collversionstr = TextDatumGetCString(datum);
 
-		actual_versionstr = get_collation_actual_version(dbform->datlocprovider, dbform->datlocprovider == COLLPROVIDER_ICU ? iculocale : collate);
+		if (dbform->datlocprovider == COLLPROVIDER_ICU)
+			locale = iculocale;
+		else if (dbform->datlocprovider == COLLPROVIDER_LIBC)
+			locale = collate;
+		else
+			locale = NULL; /* COLLPROVIDER_NONE */
+
+		actual_versionstr = get_collation_actual_version(dbform->datlocprovider, locale);
 		if (!actual_versionstr)
 			/* should not happen */
 			elog(WARNING,
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 2b5cc30955..4cf6892bee 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -2469,6 +2469,22 @@ setlocales(void)
 
 	/* set empty lc_* values to locale config if set */
 
+	if (locale_provider == COLLPROVIDER_NONE)
+	{
+		if (!lc_ctype)
+			lc_ctype = "C";
+		if (!lc_collate)
+			lc_collate = "C";
+		if (!lc_numeric)
+			lc_numeric = "C";
+		if (!lc_time)
+			lc_time = "C";
+		if (!lc_monetary)
+			lc_monetary = "C";
+		if (!lc_messages)
+			lc_messages = "C";
+	}
+
 	if (locale)
 	{
 		if (!lc_ctype)
@@ -2563,7 +2579,7 @@ usage(const char *progname)
 			 "                            set default locale in the respective category for\n"
 			 "                            new databases (default taken from environment)\n"));
 	printf(_("      --no-locale           equivalent to --locale=C\n"));
-	printf(_("      --locale-provider={libc|icu}\n"
+	printf(_("      --locale-provider={none|libc|icu}\n"
 			 "                            set default locale provider for new databases\n"));
 	printf(_("      --pwfile=FILE         read password for the new superuser from file\n"));
 	printf(_("  -T, --text-search-config=CFG\n"
@@ -2713,7 +2729,15 @@ setup_locale_encoding(void)
 {
 	setlocales();
 
-	if (locale_provider == COLLPROVIDER_LIBC &&
+	if (locale_provider == COLLPROVIDER_NONE &&
+		strcmp(lc_ctype, "C") == 0 &&
+		strcmp(lc_collate, "C") == 0 &&
+		strcmp(lc_time, "C") == 0 &&
+		strcmp(lc_numeric, "C") == 0 &&
+		strcmp(lc_monetary, "C") == 0 &&
+		strcmp(lc_messages, "C") == 0)
+		printf(_("The database cluster will be initialized with no locale.\n"));
+	else if (locale_provider == COLLPROVIDER_LIBC &&
 		strcmp(lc_ctype, lc_collate) == 0 &&
 		strcmp(lc_ctype, lc_time) == 0 &&
 		strcmp(lc_ctype, lc_numeric) == 0 &&
@@ -3387,7 +3411,9 @@ main(int argc, char *argv[])
 										 "-c debug_discard_caches=1");
 				break;
 			case 15:
-				if (strcmp(optarg, "icu") == 0)
+				if (strcmp(optarg, "none") == 0)
+					locale_provider = COLLPROVIDER_NONE;
+				else if (strcmp(optarg, "icu") == 0)
 					locale_provider = COLLPROVIDER_ICU;
 				else if (strcmp(optarg, "libc") == 0)
 					locale_provider = COLLPROVIDER_LIBC;
@@ -3426,6 +3452,7 @@ main(int argc, char *argv[])
 		exit(1);
 	}
 
+
 	if (icu_locale && locale_provider != COLLPROVIDER_ICU)
 		pg_fatal("%s cannot be specified unless locale provider \"%s\" is chosen",
 				 "--icu-locale", "icu");
diff --git a/src/bin/initdb/t/001_initdb.pl b/src/bin/initdb/t/001_initdb.pl
index 17a444d80c..fe6d224e5b 100644
--- a/src/bin/initdb/t/001_initdb.pl
+++ b/src/bin/initdb/t/001_initdb.pl
@@ -154,6 +154,35 @@ else
 		'locale provider ICU fails since no ICU support');
 }
 
+command_ok(
+	[ 'initdb', '--no-sync', '--locale-provider=none', "$tempdir/data6" ],
+	'locale provider none');
+
+command_ok(
+	[ 'initdb', '--no-sync', '--locale-provider=none', '--locale=C',
+	  "$tempdir/data7" ],
+	'locale provider none with --locale');
+
+command_ok(
+	[ 'initdb', '--no-sync', '--locale-provider=none', '--lc-collate=C',
+	  "$tempdir/data8" ],
+	'locale provider none with --lc-collate');
+
+command_ok(
+	[ 'initdb', '--no-sync', '--locale-provider=none', '--lc-ctype=C',
+	  "$tempdir/data9" ],
+	'locale provider none with --lc-ctype');
+
+command_fails(
+	[ 'initdb', '--no-sync', '--locale-provider=none', '--icu-locale=en',
+	  "$tempdir/dataX" ],
+	'fails for locale provider none with ICU locale');
+
+command_fails(
+	[ 'initdb', '--no-sync', '--locale-provider=none', '--icu-rules=""',
+	  "$tempdir/dataX" ],
+	'fails for locale provider none with ICU rules');
+
 command_fails(
 	[ 'initdb', '--no-sync', '--locale-provider=xyz', "$tempdir/dataX" ],
 	'fails for invalid locale provider');
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 41a51ec5cd..be6580ab3c 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -3070,7 +3070,9 @@ dumpDatabase(Archive *fout)
 	}
 
 	appendPQExpBufferStr(creaQry, " LOCALE_PROVIDER = ");
-	if (datlocprovider[0] == 'c')
+	if (datlocprovider[0] == 'n')
+		appendPQExpBufferStr(creaQry, "none");
+	else if (datlocprovider[0] == 'c')
 		appendPQExpBufferStr(creaQry, "libc");
 	else if (datlocprovider[0] == 'i')
 		appendPQExpBufferStr(creaQry, "icu");
@@ -13446,7 +13448,9 @@ dumpCollation(Archive *fout, const CollInfo *collinfo)
 					  fmtQualifiedDumpable(collinfo));
 
 	appendPQExpBufferStr(q, "provider = ");
-	if (collprovider[0] == 'c')
+	if (collprovider[0] == 'n')
+		appendPQExpBufferStr(q, "none");
+	else if (collprovider[0] == 'c')
 		appendPQExpBufferStr(q, "libc");
 	else if (collprovider[0] == 'i')
 		appendPQExpBufferStr(q, "icu");
diff --git a/src/bin/pg_upgrade/t/002_pg_upgrade.pl b/src/bin/pg_upgrade/t/002_pg_upgrade.pl
index 4a7895a756..6d58f6103e 100644
--- a/src/bin/pg_upgrade/t/002_pg_upgrade.pl
+++ b/src/bin/pg_upgrade/t/002_pg_upgrade.pl
@@ -114,12 +114,20 @@ my $original_locale = "C";
 my $original_iculocale = "";
 my $provider_field = "'c' AS datlocprovider";
 my $iculocale_field = "NULL AS daticulocale";
-if ($oldnode->pg_version >= 15 && $ENV{with_icu} eq 'yes')
+if ($oldnode->pg_version >= 15)
 {
 	$provider_field = "datlocprovider";
 	$iculocale_field = "daticulocale";
-	$original_provider = "i";
-	$original_iculocale = "fr-CA";
+
+	if ($ENV{with_icu} eq 'yes')
+	{
+		$original_provider = "i";
+		$original_iculocale = "fr-CA";
+	}
+	else
+	{
+		$original_provider = "n";
+	}
 }
 
 my @initdb_params = @custom_opts;
@@ -131,6 +139,10 @@ if ($original_provider eq "i")
 	push @initdb_params, ('--locale-provider', 'icu');
 	push @initdb_params, ('--icu-locale', 'fr-CA');
 }
+elsif ($original_provider eq "n")
+{
+	push @initdb_params, ('--locale-provider', 'none');
+}
 
 $node_params{extra} = \@initdb_params;
 $oldnode->init(%node_params);
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 058e41e749..16e726b784 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -932,7 +932,7 @@ listAllDbs(const char *pattern, bool verbose)
 					  gettext_noop("Encoding"));
 	if (pset.sversion >= 150000)
 		appendPQExpBuffer(&buf,
-						  "  CASE d.datlocprovider WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\",\n",
+						  "  CASE d.datlocprovider WHEN 'n' THEN 'none' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\",\n",
 						  gettext_noop("Locale Provider"));
 	else
 		appendPQExpBuffer(&buf,
diff --git a/src/bin/scripts/createdb.c b/src/bin/scripts/createdb.c
index b4205c4fa5..79367d933b 100644
--- a/src/bin/scripts/createdb.c
+++ b/src/bin/scripts/createdb.c
@@ -299,7 +299,7 @@ help(const char *progname)
 	printf(_("      --lc-ctype=LOCALE        LC_CTYPE setting for the database\n"));
 	printf(_("      --icu-locale=LOCALE      ICU locale setting for the database\n"));
 	printf(_("      --icu-rules=RULES        ICU rules setting for the database\n"));
-	printf(_("      --locale-provider={libc|icu}\n"
+	printf(_("      --locale-provider={none|libc|icu}\n"
 			 "                               locale provider for the database's default collation\n"));
 	printf(_("  -O, --owner=OWNER            database user to own the new database\n"));
 	printf(_("  -S, --strategy=STRATEGY      database creation strategy wal_log or file_copy\n"));
diff --git a/src/bin/scripts/t/020_createdb.pl b/src/bin/scripts/t/020_createdb.pl
index af3b1492e3..5aa658b671 100644
--- a/src/bin/scripts/t/020_createdb.pl
+++ b/src/bin/scripts/t/020_createdb.pl
@@ -83,6 +83,35 @@ else
 		'create database with ICU fails since no ICU support');
 }
 
+$node->command_ok(
+	[ 'createdb', '-T', 'template0', '--locale-provider=none', 'testnone1' ],
+	'create database with provider "none"');
+
+$node->command_ok(
+	[ 'createdb', '-T', 'template0', '--locale-provider=none', '--locale=C',
+	  'testnone2' ],
+	'create database with provider "none" and locale "C"');
+
+$node->command_ok(
+	[ 'createdb', '-T', 'template0', '--locale-provider=none', '--lc-collate=C',
+	  'testnone3' ],
+	'create database with provider "none" and LC_COLLATE=C');
+
+$node->command_ok(
+	[ 'createdb', '-T', 'template0', '--locale-provider=none', '--lc-ctype=C',
+	  'testnone4' ],
+	'create database with provider "none" and LC_CTYPE=C');
+
+$node->command_fails(
+	[ 'createdb', '-T', 'template0', '--locale-provider=none', '--icu-locale=en',
+	  'testnone5' ],
+	'create database with provider "none" and ICU_LOCALE="en"');
+
+$node->command_fails(
+	[ 'createdb', '-T', 'template0', '--locale-provider=none', '--icu-rules=""',
+	  'testnone6' ],
+	'create database with provider "none" and ICU_RULES=""');
+
 $node->command_fails([ 'createdb', 'foobar1' ],
 	'fails if database already exists');
 
diff --git a/src/include/catalog/pg_collation.dat b/src/include/catalog/pg_collation.dat
index b6a69d1d42..40d62416ea 100644
--- a/src/include/catalog/pg_collation.dat
+++ b/src/include/catalog/pg_collation.dat
@@ -24,8 +24,7 @@
   collname => 'POSIX', collprovider => 'c', collencoding => '-1',
   collcollate => 'POSIX', collctype => 'POSIX' },
 { oid => '962', descr => 'sorts by Unicode code point',
-  collname => 'ucs_basic', collprovider => 'c', collencoding => '6',
-  collcollate => 'C', collctype => 'C' },
+  collname => 'ucs_basic', collprovider => 'n', collencoding => '6' },
 { oid => '963',
   descr => 'sorts using the Unicode Collation Algorithm with default settings',
   collname => 'unicode', collprovider => 'i', collencoding => '-1',
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index bfa3568451..29be3f8d94 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -64,6 +64,7 @@ DECLARE_UNIQUE_INDEX_PKEY(pg_collation_oid_index, 3085, CollationOidIndexId, on
 
 #ifdef EXPOSE_TO_CLIENT_CODE
 
+#define COLLPROVIDER_NONE		'n'
 #define COLLPROVIDER_DEFAULT	'd'
 #define COLLPROVIDER_ICU		'i'
 #define COLLPROVIDER_LIBC		'c'
@@ -73,6 +74,8 @@ collprovider_name(char c)
 {
 	switch (c)
 	{
+		case COLLPROVIDER_NONE:
+			return "none";
 		case COLLPROVIDER_ICU:
 			return "icu";
 		case COLLPROVIDER_LIBC:
diff --git a/src/test/regress/expected/collate.out b/src/test/regress/expected/collate.out
index 0649564485..b7603c9f6c 100644
--- a/src/test/regress/expected/collate.out
+++ b/src/test/regress/expected/collate.out
@@ -650,6 +650,13 @@ EXPLAIN (COSTS OFF)
 (3 rows)
 
 -- CREATE/DROP COLLATION
+CREATE COLLATION none ( PROVIDER = none );
+CREATE COLLATION none2 ( PROVIDER = none, LOCALE="POSIX" ); -- fails
+ERROR:  collation provider "none" does not support LOCALE, LC_COLLATE, or LC_CTYPE
+CREATE COLLATION none2 ( PROVIDER = none, LC_CTYPE="POSIX" ); -- fails
+ERROR:  collation provider "none" does not support LOCALE, LC_COLLATE, or LC_CTYPE
+CREATE COLLATION none2 ( PROVIDER = none, LC_COLLATE="POSIX" ); -- fails
+ERROR:  collation provider "none" does not support LOCALE, LC_COLLATE, or LC_CTYPE
 CREATE COLLATION mycoll1 FROM "C";
 CREATE COLLATION mycoll2 ( LC_COLLATE = "POSIX", LC_CTYPE = "POSIX" );
 CREATE COLLATION mycoll3 FROM "default";  -- intentionally unsupported
@@ -754,7 +761,7 @@ DETAIL:  FROM cannot be specified together with any other options.
 -- must get rid of them.
 --
 DROP SCHEMA collate_tests CASCADE;
-NOTICE:  drop cascades to 19 other objects
+NOTICE:  drop cascades to 20 other objects
 DETAIL:  drop cascades to table collate_test1
 drop cascades to table collate_test_like
 drop cascades to table collate_test2
@@ -771,6 +778,7 @@ drop cascades to function dup(anyelement)
 drop cascades to table collate_test20
 drop cascades to table collate_test21
 drop cascades to table collate_test22
+drop cascades to collation "none"
 drop cascades to collation mycoll2
 drop cascades to table collate_test23
 drop cascades to view collate_on_int
diff --git a/src/test/regress/sql/collate.sql b/src/test/regress/sql/collate.sql
index c3d40fc195..e2dceb8dff 100644
--- a/src/test/regress/sql/collate.sql
+++ b/src/test/regress/sql/collate.sql
@@ -244,6 +244,12 @@ EXPLAIN (COSTS OFF)
 
 -- CREATE/DROP COLLATION
 
+CREATE COLLATION none ( PROVIDER = none );
+
+CREATE COLLATION none2 ( PROVIDER = none, LOCALE="POSIX" ); -- fails
+CREATE COLLATION none2 ( PROVIDER = none, LC_CTYPE="POSIX" ); -- fails
+CREATE COLLATION none2 ( PROVIDER = none, LC_COLLATE="POSIX" ); -- fails
+
 CREATE COLLATION mycoll1 FROM "C";
 CREATE COLLATION mycoll2 ( LC_COLLATE = "POSIX", LC_CTYPE = "POSIX" );
 CREATE COLLATION mycoll3 FROM "default";  -- intentionally unsupported
-- 
2.34.1