From 98fce30e4997253e5b010b6ac72d66255bc77bf6 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 1 Mar 2023 10:38:19 +0100
Subject: [PATCH] Add standard collation UNICODE

---
 doc/src/sgml/charset.sgml | 30 +++++++++++++++++++++++++++---
 src/bin/initdb/initdb.c   | 10 +++++++---
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 3032392b80..13ec238a81 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -659,9 +659,33 @@ <title>Standard Collations</title>
    </para>
 
    <para>
-    Additionally, the SQL standard collation name <literal>ucs_basic</literal>
-    is available for encoding <literal>UTF8</literal>.  It is equivalent
-    to <literal>C</literal> and sorts by Unicode code point.
+    Additionally, two SQL standard collation names are available for encoding
+    <literal>UTF8</literal>:
+
+    <variablelist>
+     <varlistentry>
+      <term><literal>unicode</literal></term>
+      <listitem>
+       <para>
+        This collation sorts using the Unicode Collation Algorithm with the
+        Default Unicode Collation Element Table.  (This is the same behavior
+        as the ICU root locale; see <xref
+        linkend="collation-managing-predefined-icu-und-x-icu"/>.)  This
+        collation is only available when ICU support is configured.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>ucs_basic</literal></term>
+      <listitem>
+       <para>
+        This collation sorts by Unicode code point.  (This is the same
+        behavior as the libc locale specification <literal>C</literal>.)
+       </para>
+      </listitem>
+     </varlistentry>
+    </variablelist>
    </para>
   </sect3>
 
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 7a58c33ace..525bec4b44 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1482,10 +1482,14 @@ static void
 setup_collation(FILE *cmdfd)
 {
 	/*
-	 * Add an SQL-standard name.  We don't want to pin this, so it doesn't go
-	 * in pg_collation.h.  But add it before reading system collations, so
-	 * that it wins if libc defines a locale named ucs_basic.
+	 * Add SQL-standard names.  We don't want to pin these, so they don't go
+	 * in pg_collation.h.  But add them before reading system collations, so
+	 * that they win if libc defines a locale with the same name.
 	 */
+	PG_CMD_PRINTF("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, colliculocale)"
+				  "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'unicode', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'und');\n\n",
+				  BOOTSTRAP_SUPERUSERID, COLLPROVIDER_ICU, PG_UTF8);
+
 	PG_CMD_PRINTF("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
 				  "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				  BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
-- 
2.39.2