Don't install ICU collation keyword variants

Users can still create them themselves.  Instead, document Unicode TR 35
collation options for ICU, so users can create all this themselves.

Reviewed-by: Peter Geoghegan <pg@bowt.ie>

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index f2a4acc11502bfd34faca05b5f3fd50f810aed15..44e43503a619733e31d55b75e8d542333300758f 100644 (file)
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -664,13 +664,6 @@ SELECT a COLLATE "C" < b COLLATE "POSIX" FROM test1;
       </listitem>
      </varlistentry>
 
-     <varlistentry>
-      <term><literal>de-u-co-phonebk-x-icu</literal></term>
-      <listitem>
-       <para>German collation, phone book variant</para>
-      </listitem>
-     </varlistentry>
-
      <varlistentry>
       <term><literal>de-AT-x-icu</literal></term>
       <listitem>
@@ -683,13 +676,6 @@ SELECT a COLLATE "C" &lt; b COLLATE "POSIX" FROM test1;
       </listitem>
      </varlistentry>
 
-     <varlistentry>
-      <term><literal>de-AT-u-co-phonebk-x-icu</literal></term>
-      <listitem>
-       <para>German collation for Austria, phone book variant</para>
-      </listitem>
-     </varlistentry>
-
      <varlistentry>
       <term><literal>und-x-icu</literal> (for <quote>undefined</quote>)</term>
       <listitem>
@@ -709,6 +695,90 @@ SELECT a COLLATE "C" &lt; b COLLATE "POSIX" FROM test1;
     will draw an error along the lines of <quote>collation "de-x-icu" for
     encoding "WIN874" does not exist</>.
    </para>
+
+   <para>
+    ICU allows collations to be customized beyond the basic language+country
+    set that is preloaded by <command>initdb</command>.  Users are encouraged
+    to define their own collation objects that make use of these facilities to
+    suit the sorting behavior to their requirements.  Here are some examples:
+
+    <variablelist>
+     <varlistentry>
+      <term><literal>CREATE COLLATION "de-u-co-phonebk-x-icu" (provider = icu, locale = 'de-u-co-phonebk')</literal></term>
+      <listitem>
+       <para>German collation with phone book collation type</para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>CREATE COLLATION "und-u-co-emoji-x-icu" (provider = icu, locale = 'und-u-co-emoji')</literal></term>
+      <listitem>
+       <para>
+        Root collation with Emoji collation type, per Unicode Technical Standard #51
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>CREATE COLLATION digitslast (provider = icu, locale = 'en-u-kr-latn-digit')</literal></term>
+      <listitem>
+       <para>
+        Sort digits after Latin letters.  (The default is digits before letters.)
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>CREATE COLLATION upperfirst (provider = icu, locale = 'en-u-kf-upper')</literal></term>
+      <listitem>
+       <para>
+        Sort upper-case letters before lower-case letters.  (The default is
+        lower-case letters first.)
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>CREATE COLLATION special (provider = icu, locale = 'en-u-kf-upper-kr-latn-digit')</literal></term>
+      <listitem>
+       <para>
+        Combines both of the above options.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>CREATE COLLATION numeric (provider = icu, locale = 'en-u-kn-true')</literal></term>
+      <listitem>
+       <para>
+        Numeric ordering, sorts sequences of digits by their numeric value,
+        for example: <literal>A-21</literal> &lt; <literal>A-123</literal>
+        (also known as natural sort).
+       </para>
+      </listitem>
+     </varlistentry>
+    </variablelist>
+
+    See <ulink url="http://unicode.org/reports/tr35/tr35-collation.html">Unicode
+    Technical Standard #35</ulink>
+    and <ulink url="https://tools.ietf.org/html/bcp47">BCP 47</ulink> for
+    details.  The list of possible collation types (<literal>co</literal>
+    subtag) can be found in
+    the <ulink url="http://www.unicode.org/repos/cldr/trunk/common/bcp47/collation.xml">CLDR
+    repository</ulink>.
+    The <ulink url="https://ssl.icu-project.org/icu-bin/locexp">ICU Locale
+    Explorer</ulink> can be used to check the details of a particular locale
+    definition.
+   </para>
+
+   <para>
+    Note that while this system allows creating collations that <quote>ignore
+    case</quote> or <quote>ignore accents</quote> or similar (using
+    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
+    such collations to act in a truly case- or accent-insensitive manner.  Any
+    strings that compare equal according to the collation but are not
+    byte-wise equal will be sorted according to their byte values.
+   </para>
    </sect4>
    </sect3>
 

diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index d36ce5356047c9c45a7bf553f78508b68ed09e50..9437731276f67ed49f525ce768ff630d6871bf35 100644 (file)
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -687,30 +687,11 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
                 */
                for (i = -1; i < uloc_countAvailable(); i++)
                {
-                       /*
-                        * In ICU 4.2, ucol_getKeywordValuesForLocale() sometimes returns
-                        * values that will not be accepted by uloc_toLanguageTag().  Skip
-                        * loading keyword variants in that version.  (Both
-                        * ucol_getKeywordValuesForLocale() and uloc_toLanguageTag() are
-                        * new in ICU 4.2, so older versions are not supported at all.)
-                        *
-                        * XXX We have no information about ICU 4.3 through 4.7, but we
-                        * know the code below works with 4.8.
-                        */
-#if U_ICU_VERSION_MAJOR_NUM > 4 || (U_ICU_VERSION_MAJOR_NUM == 4 && U_ICU_VERSION_MINOR_NUM > 2)
-#define LOAD_ICU_KEYWORD_VARIANTS
-#endif
-
                        const char *name;
                        char       *langtag;
                        char       *icucomment;
                        const char *collcollate;
                        Oid                     collid;
-#ifdef LOAD_ICU_KEYWORD_VARIANTS
-                       UEnumeration *en;
-                       UErrorCode      status;
-                       const char *val;
-#endif
 
                        if (i == -1)
                                name = "";              /* ICU root locale */
@@ -744,58 +725,6 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
                                        CreateComments(collid, CollationRelationId, 0,
                                                                   icucomment);
                        }
-
-                       /*
-                        * Add keyword variants, if enabled.
-                        */
-#ifdef LOAD_ICU_KEYWORD_VARIANTS
-                       status = U_ZERO_ERROR;
-                       en = ucol_getKeywordValuesForLocale("collation", name, TRUE, &status);
-                       if (U_FAILURE(status))
-                               ereport(ERROR,
-                                               (errmsg("could not get keyword values for locale \"%s\": %s",
-                                                               name, u_errorName(status))));
-
-                       status = U_ZERO_ERROR;
-                       uenum_reset(en, &status);
-                       while ((val = uenum_next(en, NULL, &status)))
-                       {
-                               char       *localeid = psprintf("%s@collation=%s", name, val);
-
-                               langtag = get_icu_language_tag(localeid);
-                               collcollate = U_ICU_VERSION_MAJOR_NUM >= 54 ? langtag : localeid;
-
-                               /*
-                                * Be paranoid about not allowing any non-ASCII strings into
-                                * pg_collation
-                                */
-                               if (!is_all_ascii(langtag) || !is_all_ascii(collcollate))
-                                       continue;
-
-                               collid = CollationCreate(psprintf("%s-x-icu", langtag),
-                                                                                nspid, GetUserId(),
-                                                                                COLLPROVIDER_ICU, -1,
-                                                                                collcollate, collcollate,
-                                                                                get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
-                                                                                true, true);
-                               if (OidIsValid(collid))
-                               {
-                                       ncreated++;
-
-                                       CommandCounterIncrement();
-
-                                       icucomment = get_icu_locale_comment(localeid);
-                                       if (icucomment)
-                                               CreateComments(collid, CollationRelationId, 0,
-                                                                          icucomment);
-                               }
-                       }
-                       if (U_FAILURE(status))
-                               ereport(ERROR,
-                                               (errmsg("could not get keyword values for locale \"%s\": %s",
-                                                               name, u_errorName(status))));
-                       uenum_close(en);
-#endif                                                 /* LOAD_ICU_KEYWORD_VARIANTS */
                }
        }
 #endif                                                 /* USE_ICU */