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Further hacking on ICU collation creation and usage.

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pg_import_system_collations() refused to create any ICU collations if
the current database's encoding didn't support ICU.  This is wrongheaded:
initdb must initialize pg_collation in an encoding-independent way
since it might be used in other databases with different encodings.
The reason for the restriction seems to be that get_icu_locale_comment()
used icu_from_uchar() to convert the UChar-format display name, and that
unsurprisingly doesn't know what to do in unsupported encodings.
But by the same token that the initial catalog contents must be
encoding-independent, we can't allow non-ASCII characters in the comment
strings.  So we don't really need icu_from_uchar() here: just check for
Unicode codes outside the ASCII range, and if there are none, the format
conversion is trivial.  If there are some, we can simply not install the
comment.  (In my testing, this affects only Norwegian Bokmål, which has
given us trouble before.)

For paranoia's sake, also check for non-ASCII characters in ICU locale
names, and skip such locales, as we do for libc locales.  I don't
currently have a reason to believe that this will ever reject anything,
but then again the libc maintainers should have known better too.

With just the import changes, ICU collations can be found in pg_collation
in databases with unsupported encodings.  This resulted in more or less
clean failures at runtime, but that's not how things act for unsupported
encodings with libc collations.  Make it work the same as our traditional
behavior for libc collations by having collation lookup take into account
whether is_encoding_supported_by_icu().

Adjust documentation to match.  Also, expand Table 23.1 to show which
encodings are supported by ICU.

catversion bump because of likely change in pg_collation/pg_description
initial contents in ICU-enabled builds.

Discussion: https://postgr.es/m/20c74bc3-d6ca-243d-1bbc-12f17fa4fe9a@gmail.com
This commit is contained in:
Tom Lane
2017-06-24 13:54:15 -04:00
parent a15b47df35
commit ddb5fdc068
4 changed files with 194 additions and 87 deletions
Download Patch File Download Diff File Expand all files Collapse all files

92
doc/src/sgml/charset.sgml
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@ -508,8 +508,8 @@ SELECT * FROM test1 ORDER BY a || b COLLATE "fr_FR";
operating system C library. These are the locales that most tools
provided by the operating system use. Another provider
is <literal>icu</literal>, which uses the external
ICU<indexterm><primary>ICU</></> library. Support for ICU has to be
configured when PostgreSQL is built.
ICU<indexterm><primary>ICU</></> library. ICU locales can only be
used if support for ICU was configured when PostgreSQL was built.
</para>
<para>
@ -529,12 +529,12 @@ SELECT * FROM test1 ORDER BY a || b COLLATE "fr_FR";
</para>
<para>
A collation provided by <literal>icu</literal> maps to a named collator
provided by the ICU library. ICU does not support
separate <quote>collate</quote> and <quote>ctype</quote> settings, so they
are always the same. Also, ICU collations are independent of the
encoding, so there is always only one ICU collation for a given name in a
database.
A collation object provided by <literal>icu</literal> maps to a named
collator provided by the ICU library. ICU does not support
separate <quote>collate</quote> and <quote>ctype</quote> settings, so
they are always the same. Also, ICU collations are independent of the
encoding, so there is always only one ICU collation of a given name in
a database.
</para>
<sect3>
@ -566,10 +566,10 @@ SELECT * FROM test1 ORDER BY a || b COLLATE "fr_FR";
<para>
If the operating system provides support for using multiple locales
within a single program (<function>newlocale</> and related functions),
or support for ICU is configured,
or if support for ICU is configured,
then when a database cluster is initialized, <command>initdb</command>
populates the system catalog <literal>pg_collation</literal> with
collations based on all the locales it finds on the operating
collations based on all the locales it finds in the operating
system at the time.
</para>
@ -602,10 +602,12 @@ SELECT * FROM test1 ORDER BY a || b COLLATE "fr_FR";
directly to the locales installed in the operating system, which can be
listed using the command <literal>locale -a</literal>. In case
a <literal>libc</literal> collation is needed that has different values
for <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol>, or new
for <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol>, or if new
locales are installed in the operating system after the database system
was initialized, then a new collation may be created using
the <xref linkend="sql-createcollation"> command.
New operating system locales can also be imported en masse using
the <link linkend="functions-admin-collation"><function>pg_import_system_collations()</function></link> function.
</para>
<para>
@ -617,8 +619,8 @@ SELECT * FROM test1 ORDER BY a || b COLLATE "fr_FR";
Use of the stripped collation names is recommended, since it will
make one less thing you need to change if you decide to change to
another database encoding. Note however that the <literal>default</>,
<literal>C</>, and <literal>POSIX</> collations, as well as all collations
provided by ICU can be used regardless of the database encoding.
<literal>C</>, and <literal>POSIX</> collations can be used regardless of
the database encoding.
</para>
<para>
@ -641,7 +643,7 @@ SELECT a COLLATE "C" &lt; b COLLATE "POSIX" FROM test1;
Collations provided by ICU are created with names in BCP 47 language tag
format, with a <quote>private use</quote>
extension <literal>-x-icu</literal> appended, to distinguish them from
libc locales. So <literal>de-x-icu</literal> would be an example.
libc locales. So <literal>de-x-icu</literal> would be an example name.
</para>
<para>
@ -652,7 +654,7 @@ SELECT a COLLATE "C" &lt; b COLLATE "POSIX" FROM test1;
See <ulink url="http://userguide.icu-project.org/locale"></ulink> for
information on ICU locale naming. <command>initdb</command> uses the ICU
APIs to extract a set of locales with distinct collation rules to populate
the initial set of collations. Here are some examples collations that
the initial set of collations. Here are some example collations that
might be created:
<variablelist>
@ -675,7 +677,7 @@ SELECT a COLLATE "C" &lt; b COLLATE "POSIX" FROM test1;
<listitem>
<para>German collation for Austria, default variant</para>
<para>
(Note that as of this writing, there is no,
(As of this writing, there is no,
say, <literal>de-DE-x-icu</literal> or <literal>de-CH-x-icu</literal>,
because those are equivalent to <literal>de-x-icu</literal>.)
</para>
@ -701,9 +703,11 @@ SELECT a COLLATE "C" &lt; b COLLATE "POSIX" FROM test1;
</para>
<para>
Some (less frequently used) encodings are not supported by ICU. If the
database cluster was initialized with such an encoding, no ICU collations
will be predefined.
Some (less frequently used) encodings are not supported by ICU. When the
database encoding is one of these, ICU collation entries
in <literal>pg_collation</literal> are ignored. Attempting to use one
will draw an error along the lines of <quote>collation "de-x-icu" for
encoding "WIN874" does not exist</>.
</para>
</sect4>
</sect3>
@ -761,8 +765,11 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
classification) and <envar>LC_COLLATE</> (string sort order) locale
settings. For <literal>C</> or
<literal>POSIX</> locale, any character set is allowed, but for other
locales there is only one character set that will work correctly.
libc-provided locales there is only one character set that will work
correctly.
(On Windows, however, UTF-8 encoding can be used with any locale.)
If you have ICU support configured, ICU-provided locales can be used
with most but not all server-side encodings.
</para>
<sect2 id="multibyte-charset-supported">
@ -775,13 +782,14 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<table id="charset-table">
<title><productname>PostgreSQL</productname> Character Sets</title>
<tgroup cols="6">
<tgroup cols="7">
<thead>
<row>
<entry>Name</entry>
<entry>Description</entry>
<entry>Language</entry>
<entry>Server?</entry>
<entry>ICU?</entry>
<!--
The Bytes/Char field is populated by looking at the values returned
by pg_wchar_table.mblen function for each encoding.
@ -796,6 +804,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Big Five</entry>
<entry>Traditional Chinese</entry>
<entry>No</entry>
<entry>No</entry>
<entry>1-2</entry>
<entry><literal>WIN950</>, <literal>Windows950</></entry>
</row>
@ -804,6 +813,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Extended UNIX Code-CN</entry>
<entry>Simplified Chinese</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1-3</entry>
<entry></entry>
</row>
@ -812,6 +822,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Extended UNIX Code-JP</entry>
<entry>Japanese</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1-3</entry>
<entry></entry>
</row>
@ -820,6 +831,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Extended UNIX Code-JP, JIS X 0213</entry>
<entry>Japanese</entry>
<entry>Yes</entry>
<entry>No</entry>
<entry>1-3</entry>
<entry></entry>
</row>
@ -828,6 +840,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Extended UNIX Code-KR</entry>
<entry>Korean</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1-3</entry>
<entry></entry>
</row>
@ -836,6 +849,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Extended UNIX Code-TW</entry>
<entry>Traditional Chinese, Taiwanese</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1-3</entry>
<entry></entry>
</row>
@ -844,6 +858,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>National Standard</entry>
<entry>Chinese</entry>
<entry>No</entry>
<entry>No</entry>
<entry>1-4</entry>
<entry></entry>
</row>
@ -852,6 +867,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Extended National Standard</entry>
<entry>Simplified Chinese</entry>
<entry>No</entry>
<entry>No</entry>
<entry>1-2</entry>
<entry><literal>WIN936</>, <literal>Windows936</></entry>
</row>
@ -860,6 +876,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-5, <acronym>ECMA</> 113</entry>
<entry>Latin/Cyrillic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -868,6 +885,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-6, <acronym>ECMA</> 114</entry>
<entry>Latin/Arabic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -876,6 +894,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-7, <acronym>ECMA</> 118</entry>
<entry>Latin/Greek</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -884,6 +903,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-8, <acronym>ECMA</> 121</entry>
<entry>Latin/Hebrew</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -892,6 +912,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry><acronym>JOHAB</></entry>
<entry>Korean (Hangul)</entry>
<entry>No</entry>
<entry>No</entry>
<entry>1-3</entry>
<entry></entry>
</row>
@ -900,6 +921,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry><acronym>KOI</acronym>8-R</entry>
<entry>Cyrillic (Russian)</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>KOI8</></entry>
</row>
@ -908,6 +930,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry><acronym>KOI</acronym>8-U</entry>
<entry>Cyrillic (Ukrainian)</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -916,6 +939,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-1, <acronym>ECMA</> 94</entry>
<entry>Western European</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO88591</></entry>
</row>
@ -924,6 +948,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-2, <acronym>ECMA</> 94</entry>
<entry>Central European</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO88592</></entry>
</row>
@ -932,6 +957,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-3, <acronym>ECMA</> 94</entry>
<entry>South European</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO88593</></entry>
</row>
@ -940,6 +966,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-4, <acronym>ECMA</> 94</entry>
<entry>North European</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO88594</></entry>
</row>
@ -948,6 +975,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-9, <acronym>ECMA</> 128</entry>
<entry>Turkish</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO88599</></entry>
</row>
@ -956,6 +984,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-10, <acronym>ECMA</> 144</entry>
<entry>Nordic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO885910</></entry>
</row>
@ -964,6 +993,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-13</entry>
<entry>Baltic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO885913</></entry>
</row>
@ -972,6 +1002,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-14</entry>
<entry>Celtic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO885914</></entry>
</row>
@ -980,6 +1011,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-15</entry>
<entry>LATIN1 with Euro and accents</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ISO885915</></entry>
</row>
@ -988,6 +1020,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>ISO 8859-16, <acronym>ASRO</> SR 14111</entry>
<entry>Romanian</entry>
<entry>Yes</entry>
<entry>No</entry>
<entry>1</entry>
<entry><literal>ISO885916</></entry>
</row>
@ -996,6 +1029,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Mule internal code</entry>
<entry>Multilingual Emacs</entry>
<entry>Yes</entry>
<entry>No</entry>
<entry>1-4</entry>
<entry></entry>
</row>
@ -1004,6 +1038,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Shift JIS</entry>
<entry>Japanese</entry>
<entry>No</entry>
<entry>No</entry>
<entry>1-2</entry>
<entry><literal>Mskanji</>, <literal>ShiftJIS</>, <literal>WIN932</>, <literal>Windows932</></entry>
</row>
@ -1012,6 +1047,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Shift JIS, JIS X 0213</entry>
<entry>Japanese</entry>
<entry>No</entry>
<entry>No</entry>
<entry>1-2</entry>
<entry></entry>
</row>
@ -1020,6 +1056,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>unspecified (see text)</entry>
<entry><emphasis>any</></entry>
<entry>Yes</entry>
<entry>No</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1028,6 +1065,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Unified Hangul Code</entry>
<entry>Korean</entry>
<entry>No</entry>
<entry>No</entry>
<entry>1-2</entry>
<entry><literal>WIN949</>, <literal>Windows949</></entry>
</row>
@ -1036,6 +1074,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Unicode, 8-bit</entry>
<entry><emphasis>all</></entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1-4</entry>
<entry><literal>Unicode</></entry>
</row>
@ -1044,6 +1083,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP866</entry>
<entry>Cyrillic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ALT</></entry>
</row>
@ -1052,6 +1092,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP874</entry>
<entry>Thai</entry>
<entry>Yes</entry>
<entry>No</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1060,6 +1101,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1250</entry>
<entry>Central European</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1068,6 +1110,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1251</entry>
<entry>Cyrillic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>WIN</></entry>
</row>
@ -1076,6 +1119,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1252</entry>
<entry>Western European</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1084,6 +1128,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1253</entry>
<entry>Greek</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1092,6 +1137,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1254</entry>
<entry>Turkish</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1100,6 +1146,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1255</entry>
<entry>Hebrew</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1108,6 +1155,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1256</entry>
<entry>Arabic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1116,6 +1164,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1257</entry>
<entry>Baltic</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry></entry>
</row>
@ -1124,6 +1173,7 @@ CREATE COLLATION "de-DE-x-icu" FROM "de-x-icu";
<entry>Windows CP1258</entry>
<entry>Vietnamese</entry>
<entry>Yes</entry>
<entry>Yes</entry>
<entry>1</entry>
<entry><literal>ABC</>, <literal>TCVN</>, <literal>TCVN5712</>, <literal>VSCII</></entry>
</row>