1<!-- doc/src/sgml/charset.sgml --> 2 3<chapter id="charset"> 4 <title>Localization</title> 5 6 <para> 7 This chapter describes the available localization features from the 8 point of view of the administrator. 9 <productname>PostgreSQL</productname> supports two localization 10 facilities: 11 12 <itemizedlist> 13 <listitem> 14 <para> 15 Using the locale features of the operating system to provide 16 locale-specific collation order, number formatting, translated 17 messages, and other aspects. 18 This is covered in <xref linkend="locale"/> and 19 <xref linkend="collation"/>. 20 </para> 21 </listitem> 22 23 <listitem> 24 <para> 25 Providing a number of different character sets to support storing text 26 in all kinds of languages, and providing character set translation 27 between client and server. 28 This is covered in <xref linkend="multibyte"/>. 29 </para> 30 </listitem> 31 </itemizedlist> 32 </para> 33 34 35 <sect1 id="locale"> 36 <title>Locale Support</title> 37 38 <indexterm zone="locale"><primary>locale</primary></indexterm> 39 40 <para> 41 <firstterm>Locale</firstterm> support refers to an application respecting 42 cultural preferences regarding alphabets, sorting, number 43 formatting, etc. <productname>PostgreSQL</productname> uses the standard ISO 44 C and <acronym>POSIX</acronym> locale facilities provided by the server operating 45 system. For additional information refer to the documentation of your 46 system. 47 </para> 48 49 <sect2> 50 <title>Overview</title> 51 52 <para> 53 Locale support is automatically initialized when a database 54 cluster is created using <command>initdb</command>. 55 <command>initdb</command> will initialize the database cluster 56 with the locale setting of its execution environment by default, 57 so if your system is already set to use the locale that you want 58 in your database cluster then there is nothing else you need to 59 do. If you want to use a different locale (or you are not sure 60 which locale your system is set to), you can instruct 61 <command>initdb</command> exactly which locale to use by 62 specifying the <option>--locale</option> option. For example: 63<screen> 64initdb --locale=sv_SE 65</screen> 66 </para> 67 68 <para> 69 This example for Unix systems sets the locale to Swedish 70 (<literal>sv</literal>) as spoken 71 in Sweden (<literal>SE</literal>). Other possibilities might include 72 <literal>en_US</literal> (U.S. English) and <literal>fr_CA</literal> (French 73 Canadian). If more than one character set can be used for a 74 locale then the specifications can take the form 75 <replaceable>language_territory.codeset</replaceable>. For example, 76 <literal>fr_BE.UTF-8</literal> represents the French language (fr) as 77 spoken in Belgium (BE), with a <acronym>UTF-8</acronym> character set 78 encoding. 79 </para> 80 81 <para> 82 What locales are available on your 83 system under what names depends on what was provided by the operating 84 system vendor and what was installed. On most Unix systems, the command 85 <literal>locale -a</literal> will provide a list of available locales. 86 Windows uses more verbose locale names, such as <literal>German_Germany</literal> 87 or <literal>Swedish_Sweden.1252</literal>, but the principles are the same. 88 </para> 89 90 <para> 91 Occasionally it is useful to mix rules from several locales, e.g., 92 use English collation rules but Spanish messages. To support that, a 93 set of locale subcategories exist that control only certain 94 aspects of the localization rules: 95 96 <informaltable> 97 <tgroup cols="2"> 98 <colspec colname="col1" colwidth="1*"/> 99 <colspec colname="col2" colwidth="3*"/> 100 <tbody> 101 <row> 102 <entry><envar>LC_COLLATE</envar></entry> 103 <entry>String sort order</entry> 104 </row> 105 <row> 106 <entry><envar>LC_CTYPE</envar></entry> 107 <entry>Character classification (What is a letter? Its upper-case equivalent?)</entry> 108 </row> 109 <row> 110 <entry><envar>LC_MESSAGES</envar></entry> 111 <entry>Language of messages</entry> 112 </row> 113 <row> 114 <entry><envar>LC_MONETARY</envar></entry> 115 <entry>Formatting of currency amounts</entry> 116 </row> 117 <row> 118 <entry><envar>LC_NUMERIC</envar></entry> 119 <entry>Formatting of numbers</entry> 120 </row> 121 <row> 122 <entry><envar>LC_TIME</envar></entry> 123 <entry>Formatting of dates and times</entry> 124 </row> 125 </tbody> 126 </tgroup> 127 </informaltable> 128 129 The category names translate into names of 130 <command>initdb</command> options to override the locale choice 131 for a specific category. For instance, to set the locale to 132 French Canadian, but use U.S. rules for formatting currency, use 133 <literal>initdb --locale=fr_CA --lc-monetary=en_US</literal>. 134 </para> 135 136 <para> 137 If you want the system to behave as if it had no locale support, 138 use the special locale name <literal>C</literal>, or equivalently 139 <literal>POSIX</literal>. 140 </para> 141 142 <para> 143 Some locale categories must have their values 144 fixed when the database is created. You can use different settings 145 for different databases, but once a database is created, you cannot 146 change them for that database anymore. <literal>LC_COLLATE</literal> 147 and <literal>LC_CTYPE</literal> are these categories. They affect 148 the sort order of indexes, so they must be kept fixed, or indexes on 149 text columns would become corrupt. 150 (But you can alleviate this restriction using collations, as discussed 151 in <xref linkend="collation"/>.) 152 The default values for these 153 categories are determined when <command>initdb</command> is run, and 154 those values are used when new databases are created, unless 155 specified otherwise in the <command>CREATE DATABASE</command> command. 156 </para> 157 158 <para> 159 The other locale categories can be changed whenever desired 160 by setting the server configuration parameters 161 that have the same name as the locale categories (see <xref 162 linkend="runtime-config-client-format"/> for details). The values 163 that are chosen by <command>initdb</command> are actually only written 164 into the configuration file <filename>postgresql.conf</filename> to 165 serve as defaults when the server is started. If you remove these 166 assignments from <filename>postgresql.conf</filename> then the 167 server will inherit the settings from its execution environment. 168 </para> 169 170 <para> 171 Note that the locale behavior of the server is determined by the 172 environment variables seen by the server, not by the environment 173 of any client. Therefore, be careful to configure the correct locale settings 174 before starting the server. A consequence of this is that if 175 client and server are set up in different locales, messages might 176 appear in different languages depending on where they originated. 177 </para> 178 179 <note> 180 <para> 181 When we speak of inheriting the locale from the execution 182 environment, this means the following on most operating systems: 183 For a given locale category, say the collation, the following 184 environment variables are consulted in this order until one is 185 found to be set: <envar>LC_ALL</envar>, <envar>LC_COLLATE</envar> 186 (or the variable corresponding to the respective category), 187 <envar>LANG</envar>. If none of these environment variables are 188 set then the locale defaults to <literal>C</literal>. 189 </para> 190 191 <para> 192 Some message localization libraries also look at the environment 193 variable <envar>LANGUAGE</envar> which overrides all other locale 194 settings for the purpose of setting the language of messages. If 195 in doubt, please refer to the documentation of your operating 196 system, in particular the documentation about 197 <application>gettext</application>. 198 </para> 199 </note> 200 201 <para> 202 To enable messages to be translated to the user's preferred language, 203 <acronym>NLS</acronym> must have been selected at build time 204 (<literal>configure --enable-nls</literal>). All other locale support is 205 built in automatically. 206 </para> 207 </sect2> 208 209 <sect2> 210 <title>Behavior</title> 211 212 <para> 213 The locale settings influence the following SQL features: 214 215 <itemizedlist> 216 <listitem> 217 <para> 218 Sort order in queries using <literal>ORDER BY</literal> or the standard 219 comparison operators on textual data 220 <indexterm><primary>ORDER BY</primary><secondary>and locales</secondary></indexterm> 221 </para> 222 </listitem> 223 224 <listitem> 225 <para> 226 The <function>upper</function>, <function>lower</function>, and <function>initcap</function> 227 functions 228 <indexterm><primary>upper</primary><secondary>and locales</secondary></indexterm> 229 <indexterm><primary>lower</primary><secondary>and locales</secondary></indexterm> 230 </para> 231 </listitem> 232 233 <listitem> 234 <para> 235 Pattern matching operators (<literal>LIKE</literal>, <literal>SIMILAR TO</literal>, 236 and POSIX-style regular expressions); locales affect both case 237 insensitive matching and the classification of characters by 238 character-class regular expressions 239 <indexterm><primary>LIKE</primary><secondary>and locales</secondary></indexterm> 240 <indexterm><primary>regular expressions</primary><secondary>and locales</secondary></indexterm> 241 </para> 242 </listitem> 243 244 <listitem> 245 <para> 246 The <function>to_char</function> family of functions 247 <indexterm><primary>to_char</primary><secondary>and locales</secondary></indexterm> 248 </para> 249 </listitem> 250 251 <listitem> 252 <para> 253 The ability to use indexes with <literal>LIKE</literal> clauses 254 </para> 255 </listitem> 256 </itemizedlist> 257 </para> 258 259 <para> 260 The drawback of using locales other than <literal>C</literal> or 261 <literal>POSIX</literal> in <productname>PostgreSQL</productname> is its performance 262 impact. It slows character handling and prevents ordinary indexes 263 from being used by <literal>LIKE</literal>. For this reason use locales 264 only if you actually need them. 265 </para> 266 267 <para> 268 As a workaround to allow <productname>PostgreSQL</productname> to use indexes 269 with <literal>LIKE</literal> clauses under a non-C locale, several custom 270 operator classes exist. These allow the creation of an index that 271 performs a strict character-by-character comparison, ignoring 272 locale comparison rules. Refer to <xref linkend="indexes-opclass"/> 273 for more information. Another approach is to create indexes using 274 the <literal>C</literal> collation, as discussed in 275 <xref linkend="collation"/>. 276 </para> 277 </sect2> 278 279 <sect2> 280 <title>Problems</title> 281 282 <para> 283 If locale support doesn't work according to the explanation above, 284 check that the locale support in your operating system is 285 correctly configured. To check what locales are installed on your 286 system, you can use the command <literal>locale -a</literal> if 287 your operating system provides it. 288 </para> 289 290 <para> 291 Check that <productname>PostgreSQL</productname> is actually using the locale 292 that you think it is. The <envar>LC_COLLATE</envar> and <envar>LC_CTYPE</envar> 293 settings are determined when a database is created, and cannot be 294 changed except by creating a new database. Other locale 295 settings including <envar>LC_MESSAGES</envar> and <envar>LC_MONETARY</envar> 296 are initially determined by the environment the server is started 297 in, but can be changed on-the-fly. You can check the active locale 298 settings using the <command>SHOW</command> command. 299 </para> 300 301 <para> 302 The directory <filename>src/test/locale</filename> in the source 303 distribution contains a test suite for 304 <productname>PostgreSQL</productname>'s locale support. 305 </para> 306 307 <para> 308 Client applications that handle server-side errors by parsing the 309 text of the error message will obviously have problems when the 310 server's messages are in a different language. Authors of such 311 applications are advised to make use of the error code scheme 312 instead. 313 </para> 314 315 <para> 316 Maintaining catalogs of message translations requires the on-going 317 efforts of many volunteers that want to see 318 <productname>PostgreSQL</productname> speak their preferred language well. 319 If messages in your language are currently not available or not fully 320 translated, your assistance would be appreciated. If you want to 321 help, refer to <xref linkend="nls"/> or write to the developers' 322 mailing list. 323 </para> 324 </sect2> 325 </sect1> 326 327 328 <sect1 id="collation"> 329 <title>Collation Support</title> 330 331 <indexterm zone="collation"><primary>collation</primary></indexterm> 332 333 <para> 334 The collation feature allows specifying the sort order and character 335 classification behavior of data per-column, or even per-operation. 336 This alleviates the restriction that the 337 <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol> settings 338 of a database cannot be changed after its creation. 339 </para> 340 341 <sect2> 342 <title>Concepts</title> 343 344 <para> 345 Conceptually, every expression of a collatable data type has a 346 collation. (The built-in collatable data types are 347 <type>text</type>, <type>varchar</type>, and <type>char</type>. 348 User-defined base types can also be marked collatable, and of course 349 a domain over a collatable data type is collatable.) If the 350 expression is a column reference, the collation of the expression is the 351 defined collation of the column. If the expression is a constant, the 352 collation is the default collation of the data type of the 353 constant. The collation of a more complex expression is derived 354 from the collations of its inputs, as described below. 355 </para> 356 357 <para> 358 The collation of an expression can be the <quote>default</quote> 359 collation, which means the locale settings defined for the 360 database. It is also possible for an expression's collation to be 361 indeterminate. In such cases, ordering operations and other 362 operations that need to know the collation will fail. 363 </para> 364 365 <para> 366 When the database system has to perform an ordering or a character 367 classification, it uses the collation of the input expression. This 368 happens, for example, with <literal>ORDER BY</literal> clauses 369 and function or operator calls such as <literal><</literal>. 370 The collation to apply for an <literal>ORDER BY</literal> clause 371 is simply the collation of the sort key. The collation to apply for a 372 function or operator call is derived from the arguments, as described 373 below. In addition to comparison operators, collations are taken into 374 account by functions that convert between lower and upper case 375 letters, such as <function>lower</function>, <function>upper</function>, and 376 <function>initcap</function>; by pattern matching operators; and by 377 <function>to_char</function> and related functions. 378 </para> 379 380 <para> 381 For a function or operator call, the collation that is derived by 382 examining the argument collations is used at run time for performing 383 the specified operation. If the result of the function or operator 384 call is of a collatable data type, the collation is also used at parse 385 time as the defined collation of the function or operator expression, 386 in case there is a surrounding expression that requires knowledge of 387 its collation. 388 </para> 389 390 <para> 391 The <firstterm>collation derivation</firstterm> of an expression can be 392 implicit or explicit. This distinction affects how collations are 393 combined when multiple different collations appear in an 394 expression. An explicit collation derivation occurs when a 395 <literal>COLLATE</literal> clause is used; all other collation 396 derivations are implicit. When multiple collations need to be 397 combined, for example in a function call, the following rules are 398 used: 399 400 <orderedlist> 401 <listitem> 402 <para> 403 If any input expression has an explicit collation derivation, then 404 all explicitly derived collations among the input expressions must be 405 the same, otherwise an error is raised. If any explicitly 406 derived collation is present, that is the result of the 407 collation combination. 408 </para> 409 </listitem> 410 411 <listitem> 412 <para> 413 Otherwise, all input expressions must have the same implicit 414 collation derivation or the default collation. If any non-default 415 collation is present, that is the result of the collation combination. 416 Otherwise, the result is the default collation. 417 </para> 418 </listitem> 419 420 <listitem> 421 <para> 422 If there are conflicting non-default implicit collations among the 423 input expressions, then the combination is deemed to have indeterminate 424 collation. This is not an error condition unless the particular 425 function being invoked requires knowledge of the collation it should 426 apply. If it does, an error will be raised at run-time. 427 </para> 428 </listitem> 429 </orderedlist> 430 431 For example, consider this table definition: 432<programlisting> 433CREATE TABLE test1 ( 434 a text COLLATE "de_DE", 435 b text COLLATE "es_ES", 436 ... 437); 438</programlisting> 439 440 Then in 441<programlisting> 442SELECT a < 'foo' FROM test1; 443</programlisting> 444 the <literal><</literal> comparison is performed according to 445 <literal>de_DE</literal> rules, because the expression combines an 446 implicitly derived collation with the default collation. But in 447<programlisting> 448SELECT a < ('foo' COLLATE "fr_FR") FROM test1; 449</programlisting> 450 the comparison is performed using <literal>fr_FR</literal> rules, 451 because the explicit collation derivation overrides the implicit one. 452 Furthermore, given 453<programlisting> 454SELECT a < b FROM test1; 455</programlisting> 456 the parser cannot determine which collation to apply, since the 457 <structfield>a</structfield> and <structfield>b</structfield> columns have conflicting 458 implicit collations. Since the <literal><</literal> operator 459 does need to know which collation to use, this will result in an 460 error. The error can be resolved by attaching an explicit collation 461 specifier to either input expression, thus: 462<programlisting> 463SELECT a < b COLLATE "de_DE" FROM test1; 464</programlisting> 465 or equivalently 466<programlisting> 467SELECT a COLLATE "de_DE" < b FROM test1; 468</programlisting> 469 On the other hand, the structurally similar case 470<programlisting> 471SELECT a || b FROM test1; 472</programlisting> 473 does not result in an error, because the <literal>||</literal> operator 474 does not care about collations: its result is the same regardless 475 of the collation. 476 </para> 477 478 <para> 479 The collation assigned to a function or operator's combined input 480 expressions is also considered to apply to the function or operator's 481 result, if the function or operator delivers a result of a collatable 482 data type. So, in 483<programlisting> 484SELECT * FROM test1 ORDER BY a || 'foo'; 485</programlisting> 486 the ordering will be done according to <literal>de_DE</literal> rules. 487 But this query: 488<programlisting> 489SELECT * FROM test1 ORDER BY a || b; 490</programlisting> 491 results in an error, because even though the <literal>||</literal> operator 492 doesn't need to know a collation, the <literal>ORDER BY</literal> clause does. 493 As before, the conflict can be resolved with an explicit collation 494 specifier: 495<programlisting> 496SELECT * FROM test1 ORDER BY a || b COLLATE "fr_FR"; 497</programlisting> 498 </para> 499 </sect2> 500 501 <sect2 id="collation-managing"> 502 <title>Managing Collations</title> 503 504 <para> 505 A collation is an SQL schema object that maps an SQL name to locales 506 provided by libraries installed in the operating system. A collation 507 definition has a <firstterm>provider</firstterm> that specifies which 508 library supplies the locale data. One standard provider name 509 is <literal>libc</literal>, which uses the locales provided by the 510 operating system C library. These are the locales that most tools 511 provided by the operating system use. Another provider 512 is <literal>icu</literal>, which uses the external 513 ICU<indexterm><primary>ICU</primary></indexterm> library. ICU locales can only be 514 used if support for ICU was configured when PostgreSQL was built. 515 </para> 516 517 <para> 518 A collation object provided by <literal>libc</literal> maps to a 519 combination of <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol> 520 settings, as accepted by the <literal>setlocale()</literal> system library call. (As 521 the name would suggest, the main purpose of a collation is to set 522 <symbol>LC_COLLATE</symbol>, which controls the sort order. But 523 it is rarely necessary in practice to have an 524 <symbol>LC_CTYPE</symbol> setting that is different from 525 <symbol>LC_COLLATE</symbol>, so it is more convenient to collect 526 these under one concept than to create another infrastructure for 527 setting <symbol>LC_CTYPE</symbol> per expression.) Also, 528 a <literal>libc</literal> collation 529 is tied to a character set encoding (see <xref linkend="multibyte"/>). 530 The same collation name may exist for different encodings. 531 </para> 532 533 <para> 534 A collation object provided by <literal>icu</literal> maps to a named 535 collator provided by the ICU library. ICU does not support 536 separate <quote>collate</quote> and <quote>ctype</quote> settings, so 537 they are always the same. Also, ICU collations are independent of the 538 encoding, so there is always only one ICU collation of a given name in 539 a database. 540 </para> 541 542 <sect3> 543 <title>Standard Collations</title> 544 545 <para> 546 On all platforms, the collations named <literal>default</literal>, 547 <literal>C</literal>, and <literal>POSIX</literal> are available. Additional 548 collations may be available depending on operating system support. 549 The <literal>default</literal> collation selects the <symbol>LC_COLLATE</symbol> 550 and <symbol>LC_CTYPE</symbol> values specified at database creation time. 551 The <literal>C</literal> and <literal>POSIX</literal> collations both specify 552 <quote>traditional C</quote> behavior, in which only the ASCII letters 553 <quote><literal>A</literal></quote> through <quote><literal>Z</literal></quote> 554 are treated as letters, and sorting is done strictly by character 555 code byte values. 556 </para> 557 558 <para> 559 Additionally, the SQL standard collation name <literal>ucs_basic</literal> 560 is available for encoding <literal>UTF8</literal>. It is equivalent 561 to <literal>C</literal> and sorts by Unicode code point. 562 </para> 563 </sect3> 564 565 <sect3> 566 <title>Predefined Collations</title> 567 568 <para> 569 If the operating system provides support for using multiple locales 570 within a single program (<function>newlocale</function> and related functions), 571 or if support for ICU is configured, 572 then when a database cluster is initialized, <command>initdb</command> 573 populates the system catalog <literal>pg_collation</literal> with 574 collations based on all the locales it finds in the operating 575 system at the time. 576 </para> 577 578 <para> 579 To inspect the currently available locales, use the query <literal>SELECT 580 * FROM pg_collation</literal>, or the command <command>\dOS+</command> 581 in <application>psql</application>. 582 </para> 583 584 <sect4> 585 <title>libc Collations</title> 586 587 <para> 588 For example, the operating system might 589 provide a locale named <literal>de_DE.utf8</literal>. 590 <command>initdb</command> would then create a collation named 591 <literal>de_DE.utf8</literal> for encoding <literal>UTF8</literal> 592 that has both <symbol>LC_COLLATE</symbol> and 593 <symbol>LC_CTYPE</symbol> set to <literal>de_DE.utf8</literal>. 594 It will also create a collation with the <literal>.utf8</literal> 595 tag stripped off the name. So you could also use the collation 596 under the name <literal>de_DE</literal>, which is less cumbersome 597 to write and makes the name less encoding-dependent. Note that, 598 nevertheless, the initial set of collation names is 599 platform-dependent. 600 </para> 601 602 <para> 603 The default set of collations provided by <literal>libc</literal> map 604 directly to the locales installed in the operating system, which can be 605 listed using the command <literal>locale -a</literal>. In case 606 a <literal>libc</literal> collation is needed that has different values 607 for <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol>, or if new 608 locales are installed in the operating system after the database system 609 was initialized, then a new collation may be created using 610 the <xref linkend="sql-createcollation"/> command. 611 New operating system locales can also be imported en masse using 612 the <link linkend="functions-admin-collation"><function>pg_import_system_collations()</function></link> function. 613 </para> 614 615 <para> 616 Within any particular database, only collations that use that 617 database's encoding are of interest. Other entries in 618 <literal>pg_collation</literal> are ignored. Thus, a stripped collation 619 name such as <literal>de_DE</literal> can be considered unique 620 within a given database even though it would not be unique globally. 621 Use of the stripped collation names is recommended, since it will 622 make one fewer thing you need to change if you decide to change to 623 another database encoding. Note however that the <literal>default</literal>, 624 <literal>C</literal>, and <literal>POSIX</literal> collations can be used regardless of 625 the database encoding. 626 </para> 627 628 <para> 629 <productname>PostgreSQL</productname> considers distinct collation 630 objects to be incompatible even when they have identical properties. 631 Thus for example, 632<programlisting> 633SELECT a COLLATE "C" < b COLLATE "POSIX" FROM test1; 634</programlisting> 635 will draw an error even though the <literal>C</literal> and <literal>POSIX</literal> 636 collations have identical behaviors. Mixing stripped and non-stripped 637 collation names is therefore not recommended. 638 </para> 639 </sect4> 640 641 <sect4> 642 <title>ICU Collations</title> 643 644 <para> 645 With ICU, it is not sensible to enumerate all possible locale names. ICU 646 uses a particular naming system for locales, but there are many more ways 647 to name a locale than there are actually distinct locales. 648 <command>initdb</command> uses the ICU APIs to extract a set of distinct 649 locales to populate the initial set of collations. Collations provided by 650 ICU are created in the SQL environment with names in BCP 47 language tag 651 format, with a <quote>private use</quote> 652 extension <literal>-x-icu</literal> appended, to distinguish them from 653 libc locales. 654 </para> 655 656 <para> 657 Here are some example collations that might be created: 658 659 <variablelist> 660 <varlistentry> 661 <term><literal>de-x-icu</literal></term> 662 <listitem> 663 <para>German collation, default variant</para> 664 </listitem> 665 </varlistentry> 666 667 <varlistentry> 668 <term><literal>de-AT-x-icu</literal></term> 669 <listitem> 670 <para>German collation for Austria, default variant</para> 671 <para> 672 (There are also, say, <literal>de-DE-x-icu</literal> 673 or <literal>de-CH-x-icu</literal>, but as of this writing, they are 674 equivalent to <literal>de-x-icu</literal>.) 675 </para> 676 </listitem> 677 </varlistentry> 678 679 <varlistentry> 680 <term><literal>und-x-icu</literal> (for <quote>undefined</quote>)</term> 681 <listitem> 682 <para> 683 ICU <quote>root</quote> collation. Use this to get a reasonable 684 language-agnostic sort order. 685 </para> 686 </listitem> 687 </varlistentry> 688 </variablelist> 689 </para> 690 691 <para> 692 Some (less frequently used) encodings are not supported by ICU. When the 693 database encoding is one of these, ICU collation entries 694 in <literal>pg_collation</literal> are ignored. Attempting to use one 695 will draw an error along the lines of <quote>collation "de-x-icu" for 696 encoding "WIN874" does not exist</quote>. 697 </para> 698 </sect4> 699 </sect3> 700 701 <sect3 id="collation-create"> 702 <title>Creating New Collation Objects</title> 703 704 <para> 705 If the standard and predefined collations are not sufficient, users can 706 create their own collation objects using the SQL 707 command <xref linkend="sql-createcollation"/>. 708 </para> 709 710 <para> 711 The standard and predefined collations are in the 712 schema <literal>pg_catalog</literal>, like all predefined objects. 713 User-defined collations should be created in user schemas. This also 714 ensures that they are saved by <command>pg_dump</command>. 715 </para> 716 717 <sect4> 718 <title>libc Collations</title> 719 720 <para> 721 New libc collations can be created like this: 722<programlisting> 723CREATE COLLATION german (provider = libc, locale = 'de_DE'); 724</programlisting> 725 The exact values that are acceptable for the <literal>locale</literal> 726 clause in this command depend on the operating system. On Unix-like 727 systems, the command <literal>locale -a</literal> will show a list. 728 </para> 729 730 <para> 731 Since the predefined libc collations already include all collations 732 defined in the operating system when the database instance is 733 initialized, it is not often necessary to manually create new ones. 734 Reasons might be if a different naming system is desired (in which case 735 see also <xref linkend="collation-copy"/>) or if the operating system has 736 been upgraded to provide new locale definitions (in which case see 737 also <link linkend="functions-admin-collation"><function>pg_import_system_collations()</function></link>). 738 </para> 739 </sect4> 740 741 <sect4> 742 <title>ICU Collations</title> 743 744 <para> 745 ICU allows collations to be customized beyond the basic language+country 746 set that is preloaded by <command>initdb</command>. Users are encouraged 747 to define their own collation objects that make use of these facilities to 748 suit the sorting behavior to their requirements. 749 See <ulink url="https://unicode-org.github.io/icu/userguide/locale/"></ulink> 750 and <ulink url="https://unicode-org.github.io/icu/userguide/collation/api.html"></ulink> for 751 information on ICU locale naming. The set of acceptable names and 752 attributes depends on the particular ICU version. 753 </para> 754 755 <para> 756 Here are some examples: 757 758 <variablelist> 759 <varlistentry> 760 <term><literal>CREATE COLLATION "de-u-co-phonebk-x-icu" (provider = icu, locale = 'de-u-co-phonebk');</literal></term> 761 <term><literal>CREATE COLLATION "de-u-co-phonebk-x-icu" (provider = icu, locale = 'de@collation=phonebook');</literal></term> 762 <listitem> 763 <para>German collation with phone book collation type</para> 764 <para> 765 The first example selects the ICU locale using a <quote>language 766 tag</quote> per BCP 47. The second example uses the traditional 767 ICU-specific locale syntax. The first style is preferred going 768 forward, but it is not supported by older ICU versions. 769 </para> 770 <para> 771 Note that you can name the collation objects in the SQL environment 772 anything you want. In this example, we follow the naming style that 773 the predefined collations use, which in turn also follow BCP 47, but 774 that is not required for user-defined collations. 775 </para> 776 </listitem> 777 </varlistentry> 778 779 <varlistentry> 780 <term><literal>CREATE COLLATION "und-u-co-emoji-x-icu" (provider = icu, locale = 'und-u-co-emoji');</literal></term> 781 <term><literal>CREATE COLLATION "und-u-co-emoji-x-icu" (provider = icu, locale = '@collation=emoji');</literal></term> 782 <listitem> 783 <para> 784 Root collation with Emoji collation type, per Unicode Technical Standard #51 785 </para> 786 <para> 787 Observe how in the traditional ICU locale naming system, the root 788 locale is selected by an empty string. 789 </para> 790 </listitem> 791 </varlistentry> 792 793 <varlistentry> 794 <term><literal>CREATE COLLATION latinlast (provider = icu, locale = 'en-u-kr-grek-latn');</literal></term> 795 <term><literal>CREATE COLLATION latinlast (provider = icu, locale = 'en@colReorder=grek-latn');</literal></term> 796 <listitem> 797 <para> 798 Sort Greek letters before Latin ones. (The default is Latin before Greek.) 799 </para> 800 </listitem> 801 </varlistentry> 802 803 <varlistentry> 804 <term><literal>CREATE COLLATION upperfirst (provider = icu, locale = 'en-u-kf-upper');</literal></term> 805 <term><literal>CREATE COLLATION upperfirst (provider = icu, locale = 'en@colCaseFirst=upper');</literal></term> 806 <listitem> 807 <para> 808 Sort upper-case letters before lower-case letters. (The default is 809 lower-case letters first.) 810 </para> 811 </listitem> 812 </varlistentry> 813 814 <varlistentry> 815 <term><literal>CREATE COLLATION special (provider = icu, locale = 'en-u-kf-upper-kr-grek-latn');</literal></term> 816 <term><literal>CREATE COLLATION special (provider = icu, locale = 'en@colCaseFirst=upper;colReorder=grek-latn');</literal></term> 817 <listitem> 818 <para> 819 Combines both of the above options. 820 </para> 821 </listitem> 822 </varlistentry> 823 824 <varlistentry> 825 <term><literal>CREATE COLLATION numeric (provider = icu, locale = 'en-u-kn-true');</literal></term> 826 <term><literal>CREATE COLLATION numeric (provider = icu, locale = 'en@colNumeric=yes');</literal></term> 827 <listitem> 828 <para> 829 Numeric ordering, sorts sequences of digits by their numeric value, 830 for example: <literal>A-21</literal> < <literal>A-123</literal> 831 (also known as natural sort). 832 </para> 833 </listitem> 834 </varlistentry> 835 </variablelist> 836 837 See <ulink url="https://www.unicode.org/reports/tr35/tr35-collation.html">Unicode 838 Technical Standard #35</ulink> 839 and <ulink url="https://tools.ietf.org/html/bcp47">BCP 47</ulink> for 840 details. The list of possible collation types (<literal>co</literal> 841 subtag) can be found in 842 the <ulink url="https://github.com/unicode-org/cldr/blob/master/common/bcp47/collation.xml">CLDR 843 repository</ulink>. 844 </para> 845 846 <para> 847 Note that while this system allows creating collations that <quote>ignore 848 case</quote> or <quote>ignore accents</quote> or similar (using the 849 <literal>ks</literal> key), in order for such collations to act in a 850 truly case- or accent-insensitive manner, they also need to be declared as not 851 <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>; 852 see <xref linkend="collation-nondeterministic"/>. 853 Otherwise, any strings that compare equal according to the collation but 854 are not byte-wise equal will be sorted according to their byte values. 855 </para> 856 857 <note> 858 <para> 859 By design, ICU will accept almost any string as a locale name and match 860 it to the closest locale it can provide, using the fallback procedure 861 described in its documentation. Thus, there will be no direct feedback 862 if a collation specification is composed using features that the given 863 ICU installation does not actually support. It is therefore recommended 864 to create application-level test cases to check that the collation 865 definitions satisfy one's requirements. 866 </para> 867 </note> 868 </sect4> 869 870 <sect4 id="collation-copy"> 871 <title>Copying Collations</title> 872 873 <para> 874 The command <xref linkend="sql-createcollation"/> can also be used to 875 create a new collation from an existing collation, which can be useful to 876 be able to use operating-system-independent collation names in 877 applications, create compatibility names, or use an ICU-provided collation 878 under a more readable name. For example: 879<programlisting> 880CREATE COLLATION german FROM "de_DE"; 881CREATE COLLATION french FROM "fr-x-icu"; 882</programlisting> 883 </para> 884 </sect4> 885 </sect3> 886 887 <sect3 id="collation-nondeterministic"> 888 <title>Nondeterministic Collations</title> 889 890 <para> 891 A collation is either <firstterm>deterministic</firstterm> or 892 <firstterm>nondeterministic</firstterm>. A deterministic collation uses 893 deterministic comparisons, which means that it considers strings to be 894 equal only if they consist of the same byte sequence. Nondeterministic 895 comparison may determine strings to be equal even if they consist of 896 different bytes. Typical situations include case-insensitive comparison, 897 accent-insensitive comparison, as well as comparison of strings in 898 different Unicode normal forms. It is up to the collation provider to 899 actually implement such insensitive comparisons; the deterministic flag 900 only determines whether ties are to be broken using bytewise comparison. 901 See also <ulink url="https://www.unicode.org/reports/tr10">Unicode Technical 902 Standard 10</ulink> for more information on the terminology. 903 </para> 904 905 <para> 906 To create a nondeterministic collation, specify the property 907 <literal>deterministic = false</literal> to <command>CREATE 908 COLLATION</command>, for example: 909<programlisting> 910CREATE COLLATION ndcoll (provider = icu, locale = 'und', deterministic = false); 911</programlisting> 912 This example would use the standard Unicode collation in a 913 nondeterministic way. In particular, this would allow strings in 914 different normal forms to be compared correctly. More interesting 915 examples make use of the ICU customization facilities explained above. 916 For example: 917<programlisting> 918CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false); 919CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false); 920</programlisting> 921 </para> 922 923 <para> 924 All standard and predefined collations are deterministic, all 925 user-defined collations are deterministic by default. While 926 nondeterministic collations give a more <quote>correct</quote> behavior, 927 especially when considering the full power of Unicode and its many 928 special cases, they also have some drawbacks. Foremost, their use leads 929 to a performance penalty. Note, in particular, that B-tree cannot use 930 deduplication with indexes that use a nondeterministic collation. Also, 931 certain operations are not possible with nondeterministic collations, 932 such as pattern matching operations. Therefore, they should be used 933 only in cases where they are specifically wanted. 934 </para> 935 936 <tip> 937 <para> 938 To deal with text in different Unicode normalization forms, it is also 939 an option to use the functions/expressions 940 <function>normalize</function> and <literal>is normalized</literal> to 941 preprocess or check the strings, instead of using nondeterministic 942 collations. There are different trade-offs for each approach. 943 </para> 944 </tip> 945 </sect3> 946 </sect2> 947 </sect1> 948 949 <sect1 id="multibyte"> 950 <title>Character Set Support</title> 951 952 <indexterm zone="multibyte"><primary>character set</primary></indexterm> 953 954 <para> 955 The character set support in <productname>PostgreSQL</productname> 956 allows you to store text in a variety of character sets (also called 957 encodings), including 958 single-byte character sets such as the ISO 8859 series and 959 multiple-byte character sets such as <acronym>EUC</acronym> (Extended Unix 960 Code), UTF-8, and Mule internal code. All supported character sets 961 can be used transparently by clients, but a few are not supported 962 for use within the server (that is, as a server-side encoding). 963 The default character set is selected while 964 initializing your <productname>PostgreSQL</productname> database 965 cluster using <command>initdb</command>. It can be overridden when you 966 create a database, so you can have multiple 967 databases each with a different character set. 968 </para> 969 970 <para> 971 An important restriction, however, is that each database's character set 972 must be compatible with the database's <envar>LC_CTYPE</envar> (character 973 classification) and <envar>LC_COLLATE</envar> (string sort order) locale 974 settings. For <literal>C</literal> or 975 <literal>POSIX</literal> locale, any character set is allowed, but for other 976 libc-provided locales there is only one character set that will work 977 correctly. 978 (On Windows, however, UTF-8 encoding can be used with any locale.) 979 If you have ICU support configured, ICU-provided locales can be used 980 with most but not all server-side encodings. 981 </para> 982 983 <sect2 id="multibyte-charset-supported"> 984 <title>Supported Character Sets</title> 985 986 <para> 987 <xref linkend="charset-table"/> shows the character sets available 988 for use in <productname>PostgreSQL</productname>. 989 </para> 990 991 <table id="charset-table"> 992 <title><productname>PostgreSQL</productname> Character Sets</title> 993 <tgroup cols="7"> 994 <colspec colname="col1" colwidth="3*"/> 995 <colspec colname="col2" colwidth="2*"/> 996 <colspec colname="col3" colwidth="2*"/> 997 <colspec colname="col4" colwidth="1.25*"/> 998 <colspec colname="col5" colwidth="1*"/> 999 <colspec colname="col6" colwidth="1*"/> 1000 <colspec colname="col7" colwidth="2*"/> 1001 <thead> 1002 <row> 1003 <entry>Name</entry> 1004 <entry>Description</entry> 1005 <entry>Language</entry> 1006 <entry>Server?</entry> 1007 <entry>ICU?</entry> 1008 <!-- 1009 The Bytes/Char field is populated by looking at the values returned 1010 by pg_wchar_table.mblen function for each encoding. 1011 --> 1012 <entry>Bytes/&zwsp;Char</entry> 1013 <entry>Aliases</entry> 1014 </row> 1015 </thead> 1016 <tbody> 1017 <row> 1018 <entry><literal>BIG5</literal></entry> 1019 <entry>Big Five</entry> 1020 <entry>Traditional Chinese</entry> 1021 <entry>No</entry> 1022 <entry>No</entry> 1023 <entry>1–2</entry> 1024 <entry><literal>WIN950</literal>, <literal>Windows950</literal></entry> 1025 </row> 1026 <row> 1027 <entry><literal>EUC_CN</literal></entry> 1028 <entry>Extended UNIX Code-CN</entry> 1029 <entry>Simplified Chinese</entry> 1030 <entry>Yes</entry> 1031 <entry>Yes</entry> 1032 <entry>1–3</entry> 1033 <entry></entry> 1034 </row> 1035 <row> 1036 <entry><literal>EUC_JP</literal></entry> 1037 <entry>Extended UNIX Code-JP</entry> 1038 <entry>Japanese</entry> 1039 <entry>Yes</entry> 1040 <entry>Yes</entry> 1041 <entry>1–3</entry> 1042 <entry></entry> 1043 </row> 1044 <row> 1045 <entry><literal>EUC_JIS_2004</literal></entry> 1046 <entry>Extended UNIX Code-JP, JIS X 0213</entry> 1047 <entry>Japanese</entry> 1048 <entry>Yes</entry> 1049 <entry>No</entry> 1050 <entry>1–3</entry> 1051 <entry></entry> 1052 </row> 1053 <row> 1054 <entry><literal>EUC_KR</literal></entry> 1055 <entry>Extended UNIX Code-KR</entry> 1056 <entry>Korean</entry> 1057 <entry>Yes</entry> 1058 <entry>Yes</entry> 1059 <entry>1–3</entry> 1060 <entry></entry> 1061 </row> 1062 <row> 1063 <entry><literal>EUC_TW</literal></entry> 1064 <entry>Extended UNIX Code-TW</entry> 1065 <entry>Traditional Chinese, Taiwanese</entry> 1066 <entry>Yes</entry> 1067 <entry>Yes</entry> 1068 <entry>1–3</entry> 1069 <entry></entry> 1070 </row> 1071 <row> 1072 <entry><literal>GB18030</literal></entry> 1073 <entry>National Standard</entry> 1074 <entry>Chinese</entry> 1075 <entry>No</entry> 1076 <entry>No</entry> 1077 <entry>1–4</entry> 1078 <entry></entry> 1079 </row> 1080 <row> 1081 <entry><literal>GBK</literal></entry> 1082 <entry>Extended National Standard</entry> 1083 <entry>Simplified Chinese</entry> 1084 <entry>No</entry> 1085 <entry>No</entry> 1086 <entry>1–2</entry> 1087 <entry><literal>WIN936</literal>, <literal>Windows936</literal></entry> 1088 </row> 1089 <row> 1090 <entry><literal>ISO_8859_5</literal></entry> 1091 <entry>ISO 8859-5, <acronym>ECMA</acronym> 113</entry> 1092 <entry>Latin/Cyrillic</entry> 1093 <entry>Yes</entry> 1094 <entry>Yes</entry> 1095 <entry>1</entry> 1096 <entry></entry> 1097 </row> 1098 <row> 1099 <entry><literal>ISO_8859_6</literal></entry> 1100 <entry>ISO 8859-6, <acronym>ECMA</acronym> 114</entry> 1101 <entry>Latin/Arabic</entry> 1102 <entry>Yes</entry> 1103 <entry>Yes</entry> 1104 <entry>1</entry> 1105 <entry></entry> 1106 </row> 1107 <row> 1108 <entry><literal>ISO_8859_7</literal></entry> 1109 <entry>ISO 8859-7, <acronym>ECMA</acronym> 118</entry> 1110 <entry>Latin/Greek</entry> 1111 <entry>Yes</entry> 1112 <entry>Yes</entry> 1113 <entry>1</entry> 1114 <entry></entry> 1115 </row> 1116 <row> 1117 <entry><literal>ISO_8859_8</literal></entry> 1118 <entry>ISO 8859-8, <acronym>ECMA</acronym> 121</entry> 1119 <entry>Latin/Hebrew</entry> 1120 <entry>Yes</entry> 1121 <entry>Yes</entry> 1122 <entry>1</entry> 1123 <entry></entry> 1124 </row> 1125 <row> 1126 <entry><literal>JOHAB</literal></entry> 1127 <entry><acronym>JOHAB</acronym></entry> 1128 <entry>Korean (Hangul)</entry> 1129 <entry>No</entry> 1130 <entry>No</entry> 1131 <entry>1–3</entry> 1132 <entry></entry> 1133 </row> 1134 <row> 1135 <entry><literal>KOI8R</literal></entry> 1136 <entry><acronym>KOI</acronym>8-R</entry> 1137 <entry>Cyrillic (Russian)</entry> 1138 <entry>Yes</entry> 1139 <entry>Yes</entry> 1140 <entry>1</entry> 1141 <entry><literal>KOI8</literal></entry> 1142 </row> 1143 <row> 1144 <entry><literal>KOI8U</literal></entry> 1145 <entry><acronym>KOI</acronym>8-U</entry> 1146 <entry>Cyrillic (Ukrainian)</entry> 1147 <entry>Yes</entry> 1148 <entry>Yes</entry> 1149 <entry>1</entry> 1150 <entry></entry> 1151 </row> 1152 <row> 1153 <entry><literal>LATIN1</literal></entry> 1154 <entry>ISO 8859-1, <acronym>ECMA</acronym> 94</entry> 1155 <entry>Western European</entry> 1156 <entry>Yes</entry> 1157 <entry>Yes</entry> 1158 <entry>1</entry> 1159 <entry><literal>ISO88591</literal></entry> 1160 </row> 1161 <row> 1162 <entry><literal>LATIN2</literal></entry> 1163 <entry>ISO 8859-2, <acronym>ECMA</acronym> 94</entry> 1164 <entry>Central European</entry> 1165 <entry>Yes</entry> 1166 <entry>Yes</entry> 1167 <entry>1</entry> 1168 <entry><literal>ISO88592</literal></entry> 1169 </row> 1170 <row> 1171 <entry><literal>LATIN3</literal></entry> 1172 <entry>ISO 8859-3, <acronym>ECMA</acronym> 94</entry> 1173 <entry>South European</entry> 1174 <entry>Yes</entry> 1175 <entry>Yes</entry> 1176 <entry>1</entry> 1177 <entry><literal>ISO88593</literal></entry> 1178 </row> 1179 <row> 1180 <entry><literal>LATIN4</literal></entry> 1181 <entry>ISO 8859-4, <acronym>ECMA</acronym> 94</entry> 1182 <entry>North European</entry> 1183 <entry>Yes</entry> 1184 <entry>Yes</entry> 1185 <entry>1</entry> 1186 <entry><literal>ISO88594</literal></entry> 1187 </row> 1188 <row> 1189 <entry><literal>LATIN5</literal></entry> 1190 <entry>ISO 8859-9, <acronym>ECMA</acronym> 128</entry> 1191 <entry>Turkish</entry> 1192 <entry>Yes</entry> 1193 <entry>Yes</entry> 1194 <entry>1</entry> 1195 <entry><literal>ISO88599</literal></entry> 1196 </row> 1197 <row> 1198 <entry><literal>LATIN6</literal></entry> 1199 <entry>ISO 8859-10, <acronym>ECMA</acronym> 144</entry> 1200 <entry>Nordic</entry> 1201 <entry>Yes</entry> 1202 <entry>Yes</entry> 1203 <entry>1</entry> 1204 <entry><literal>ISO885910</literal></entry> 1205 </row> 1206 <row> 1207 <entry><literal>LATIN7</literal></entry> 1208 <entry>ISO 8859-13</entry> 1209 <entry>Baltic</entry> 1210 <entry>Yes</entry> 1211 <entry>Yes</entry> 1212 <entry>1</entry> 1213 <entry><literal>ISO885913</literal></entry> 1214 </row> 1215 <row> 1216 <entry><literal>LATIN8</literal></entry> 1217 <entry>ISO 8859-14</entry> 1218 <entry>Celtic</entry> 1219 <entry>Yes</entry> 1220 <entry>Yes</entry> 1221 <entry>1</entry> 1222 <entry><literal>ISO885914</literal></entry> 1223 </row> 1224 <row> 1225 <entry><literal>LATIN9</literal></entry> 1226 <entry>ISO 8859-15</entry> 1227 <entry>LATIN1 with Euro and accents</entry> 1228 <entry>Yes</entry> 1229 <entry>Yes</entry> 1230 <entry>1</entry> 1231 <entry><literal>ISO885915</literal></entry> 1232 </row> 1233 <row> 1234 <entry><literal>LATIN10</literal></entry> 1235 <entry>ISO 8859-16, <acronym>ASRO</acronym> SR 14111</entry> 1236 <entry>Romanian</entry> 1237 <entry>Yes</entry> 1238 <entry>No</entry> 1239 <entry>1</entry> 1240 <entry><literal>ISO885916</literal></entry> 1241 </row> 1242 <row> 1243 <entry><literal>MULE_INTERNAL</literal></entry> 1244 <entry>Mule internal code</entry> 1245 <entry>Multilingual Emacs</entry> 1246 <entry>Yes</entry> 1247 <entry>No</entry> 1248 <entry>1–4</entry> 1249 <entry></entry> 1250 </row> 1251 <row> 1252 <entry><literal>SJIS</literal></entry> 1253 <entry>Shift JIS</entry> 1254 <entry>Japanese</entry> 1255 <entry>No</entry> 1256 <entry>No</entry> 1257 <entry>1–2</entry> 1258 <entry><literal>Mskanji</literal>, <literal>ShiftJIS</literal>, <literal>WIN932</literal>, <literal>Windows932</literal></entry> 1259 </row> 1260 <row> 1261 <entry><literal>SHIFT_JIS_2004</literal></entry> 1262 <entry>Shift JIS, JIS X 0213</entry> 1263 <entry>Japanese</entry> 1264 <entry>No</entry> 1265 <entry>No</entry> 1266 <entry>1–2</entry> 1267 <entry></entry> 1268 </row> 1269 <row> 1270 <entry><literal>SQL_ASCII</literal></entry> 1271 <entry>unspecified (see text)</entry> 1272 <entry><emphasis>any</emphasis></entry> 1273 <entry>Yes</entry> 1274 <entry>No</entry> 1275 <entry>1</entry> 1276 <entry></entry> 1277 </row> 1278 <row> 1279 <entry><literal>UHC</literal></entry> 1280 <entry>Unified Hangul Code</entry> 1281 <entry>Korean</entry> 1282 <entry>No</entry> 1283 <entry>No</entry> 1284 <entry>1–2</entry> 1285 <entry><literal>WIN949</literal>, <literal>Windows949</literal></entry> 1286 </row> 1287 <row> 1288 <entry><literal>UTF8</literal></entry> 1289 <entry>Unicode, 8-bit</entry> 1290 <entry><emphasis>all</emphasis></entry> 1291 <entry>Yes</entry> 1292 <entry>Yes</entry> 1293 <entry>1–4</entry> 1294 <entry><literal>Unicode</literal></entry> 1295 </row> 1296 <row> 1297 <entry><literal>WIN866</literal></entry> 1298 <entry>Windows CP866</entry> 1299 <entry>Cyrillic</entry> 1300 <entry>Yes</entry> 1301 <entry>Yes</entry> 1302 <entry>1</entry> 1303 <entry><literal>ALT</literal></entry> 1304 </row> 1305 <row> 1306 <entry><literal>WIN874</literal></entry> 1307 <entry>Windows CP874</entry> 1308 <entry>Thai</entry> 1309 <entry>Yes</entry> 1310 <entry>No</entry> 1311 <entry>1</entry> 1312 <entry></entry> 1313 </row> 1314 <row> 1315 <entry><literal>WIN1250</literal></entry> 1316 <entry>Windows CP1250</entry> 1317 <entry>Central European</entry> 1318 <entry>Yes</entry> 1319 <entry>Yes</entry> 1320 <entry>1</entry> 1321 <entry></entry> 1322 </row> 1323 <row> 1324 <entry><literal>WIN1251</literal></entry> 1325 <entry>Windows CP1251</entry> 1326 <entry>Cyrillic</entry> 1327 <entry>Yes</entry> 1328 <entry>Yes</entry> 1329 <entry>1</entry> 1330 <entry><literal>WIN</literal></entry> 1331 </row> 1332 <row> 1333 <entry><literal>WIN1252</literal></entry> 1334 <entry>Windows CP1252</entry> 1335 <entry>Western European</entry> 1336 <entry>Yes</entry> 1337 <entry>Yes</entry> 1338 <entry>1</entry> 1339 <entry></entry> 1340 </row> 1341 <row> 1342 <entry><literal>WIN1253</literal></entry> 1343 <entry>Windows CP1253</entry> 1344 <entry>Greek</entry> 1345 <entry>Yes</entry> 1346 <entry>Yes</entry> 1347 <entry>1</entry> 1348 <entry></entry> 1349 </row> 1350 <row> 1351 <entry><literal>WIN1254</literal></entry> 1352 <entry>Windows CP1254</entry> 1353 <entry>Turkish</entry> 1354 <entry>Yes</entry> 1355 <entry>Yes</entry> 1356 <entry>1</entry> 1357 <entry></entry> 1358 </row> 1359 <row> 1360 <entry><literal>WIN1255</literal></entry> 1361 <entry>Windows CP1255</entry> 1362 <entry>Hebrew</entry> 1363 <entry>Yes</entry> 1364 <entry>Yes</entry> 1365 <entry>1</entry> 1366 <entry></entry> 1367 </row> 1368 <row> 1369 <entry><literal>WIN1256</literal></entry> 1370 <entry>Windows CP1256</entry> 1371 <entry>Arabic</entry> 1372 <entry>Yes</entry> 1373 <entry>Yes</entry> 1374 <entry>1</entry> 1375 <entry></entry> 1376 </row> 1377 <row> 1378 <entry><literal>WIN1257</literal></entry> 1379 <entry>Windows CP1257</entry> 1380 <entry>Baltic</entry> 1381 <entry>Yes</entry> 1382 <entry>Yes</entry> 1383 <entry>1</entry> 1384 <entry></entry> 1385 </row> 1386 <row> 1387 <entry><literal>WIN1258</literal></entry> 1388 <entry>Windows CP1258</entry> 1389 <entry>Vietnamese</entry> 1390 <entry>Yes</entry> 1391 <entry>Yes</entry> 1392 <entry>1</entry> 1393 <entry><literal>ABC</literal>, <literal>TCVN</literal>, <literal>TCVN5712</literal>, <literal>VSCII</literal></entry> 1394 </row> 1395 </tbody> 1396 </tgroup> 1397 </table> 1398 1399 <para> 1400 Not all client <acronym>API</acronym>s support all the listed character sets. For example, the 1401 <productname>PostgreSQL</productname> 1402 JDBC driver does not support <literal>MULE_INTERNAL</literal>, <literal>LATIN6</literal>, 1403 <literal>LATIN8</literal>, and <literal>LATIN10</literal>. 1404 </para> 1405 1406 <para> 1407 The <literal>SQL_ASCII</literal> setting behaves considerably differently 1408 from the other settings. When the server character set is 1409 <literal>SQL_ASCII</literal>, the server interprets byte values 0–127 1410 according to the ASCII standard, while byte values 128–255 are taken 1411 as uninterpreted characters. No encoding conversion will be done when 1412 the setting is <literal>SQL_ASCII</literal>. Thus, this setting is not so 1413 much a declaration that a specific encoding is in use, as a declaration 1414 of ignorance about the encoding. In most cases, if you are 1415 working with any non-ASCII data, it is unwise to use the 1416 <literal>SQL_ASCII</literal> setting because 1417 <productname>PostgreSQL</productname> will be unable to help you by 1418 converting or validating non-ASCII characters. 1419 </para> 1420 </sect2> 1421 1422 <sect2> 1423 <title>Setting the Character Set</title> 1424 1425 <para> 1426 <command>initdb</command> defines the default character set (encoding) 1427 for a <productname>PostgreSQL</productname> cluster. For example, 1428 1429<screen> 1430initdb -E EUC_JP 1431</screen> 1432 1433 sets the default character set to 1434 <literal>EUC_JP</literal> (Extended Unix Code for Japanese). You 1435 can use <option>--encoding</option> instead of 1436 <option>-E</option> if you prefer longer option strings. 1437 If no <option>-E</option> or <option>--encoding</option> option is 1438 given, <command>initdb</command> attempts to determine the appropriate 1439 encoding to use based on the specified or default locale. 1440 </para> 1441 1442 <para> 1443 You can specify a non-default encoding at database creation time, 1444 provided that the encoding is compatible with the selected locale: 1445 1446<screen> 1447createdb -E EUC_KR -T template0 --lc-collate=ko_KR.euckr --lc-ctype=ko_KR.euckr korean 1448</screen> 1449 1450 This will create a database named <literal>korean</literal> that 1451 uses the character set <literal>EUC_KR</literal>, and locale <literal>ko_KR</literal>. 1452 Another way to accomplish this is to use this SQL command: 1453 1454<programlisting> 1455CREATE DATABASE korean WITH ENCODING 'EUC_KR' LC_COLLATE='ko_KR.euckr' LC_CTYPE='ko_KR.euckr' TEMPLATE=template0; 1456</programlisting> 1457 1458 Notice that the above commands specify copying the <literal>template0</literal> 1459 database. When copying any other database, the encoding and locale 1460 settings cannot be changed from those of the source database, because 1461 that might result in corrupt data. For more information see 1462 <xref linkend="manage-ag-templatedbs"/>. 1463 </para> 1464 1465 <para> 1466 The encoding for a database is stored in the system catalog 1467 <literal>pg_database</literal>. You can see it by using the 1468 <command>psql</command> <option>-l</option> option or the 1469 <command>\l</command> command. 1470 1471<screen> 1472$ <userinput>psql -l</userinput> 1473 List of databases 1474 Name | Owner | Encoding | Collation | Ctype | Access Privileges 1475-----------+----------+-----------+-------------+-------------+------------------------------------- 1476 clocaledb | hlinnaka | SQL_ASCII | C | C | 1477 englishdb | hlinnaka | UTF8 | en_GB.UTF8 | en_GB.UTF8 | 1478 japanese | hlinnaka | UTF8 | ja_JP.UTF8 | ja_JP.UTF8 | 1479 korean | hlinnaka | EUC_KR | ko_KR.euckr | ko_KR.euckr | 1480 postgres | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 | 1481 template0 | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 | {=c/hlinnaka,hlinnaka=CTc/hlinnaka} 1482 template1 | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 | {=c/hlinnaka,hlinnaka=CTc/hlinnaka} 1483(7 rows) 1484</screen> 1485 </para> 1486 1487 <important> 1488 <para> 1489 On most modern operating systems, <productname>PostgreSQL</productname> 1490 can determine which character set is implied by the <envar>LC_CTYPE</envar> 1491 setting, and it will enforce that only the matching database encoding is 1492 used. On older systems it is your responsibility to ensure that you use 1493 the encoding expected by the locale you have selected. A mistake in 1494 this area is likely to lead to strange behavior of locale-dependent 1495 operations such as sorting. 1496 </para> 1497 1498 <para> 1499 <productname>PostgreSQL</productname> will allow superusers to create 1500 databases with <literal>SQL_ASCII</literal> encoding even when 1501 <envar>LC_CTYPE</envar> is not <literal>C</literal> or <literal>POSIX</literal>. As noted 1502 above, <literal>SQL_ASCII</literal> does not enforce that the data stored in 1503 the database has any particular encoding, and so this choice poses risks 1504 of locale-dependent misbehavior. Using this combination of settings is 1505 deprecated and may someday be forbidden altogether. 1506 </para> 1507 </important> 1508 </sect2> 1509 1510 <sect2> 1511 <title>Automatic Character Set Conversion Between Server and Client</title> 1512 1513 <para> 1514 <productname>PostgreSQL</productname> supports automatic character 1515 set conversion between server and client for many combinations of 1516 character sets (<xref linkend="multibyte-conversions-supported"/> 1517 shows which ones). 1518 </para> 1519 1520 <para> 1521 To enable automatic character set conversion, you have to 1522 tell <productname>PostgreSQL</productname> the character set 1523 (encoding) you would like to use in the client. There are several 1524 ways to accomplish this: 1525 1526 <itemizedlist> 1527 <listitem> 1528 <para> 1529 Using the <command>\encoding</command> command in 1530 <application>psql</application>. 1531 <command>\encoding</command> allows you to change client 1532 encoding on the fly. For 1533 example, to change the encoding to <literal>SJIS</literal>, type: 1534 1535<programlisting> 1536\encoding SJIS 1537</programlisting> 1538 </para> 1539 </listitem> 1540 1541 <listitem> 1542 <para> 1543 <application>libpq</application> (<xref linkend="libpq-control"/>) has functions to control the client encoding. 1544 </para> 1545 </listitem> 1546 1547 <listitem> 1548 <para> 1549 Using <command>SET client_encoding TO</command>. 1550 1551 Setting the client encoding can be done with this SQL command: 1552 1553<programlisting> 1554SET CLIENT_ENCODING TO '<replaceable>value</replaceable>'; 1555</programlisting> 1556 1557 Also you can use the standard SQL syntax <literal>SET NAMES</literal> 1558 for this purpose: 1559 1560<programlisting> 1561SET NAMES '<replaceable>value</replaceable>'; 1562</programlisting> 1563 1564 To query the current client encoding: 1565 1566<programlisting> 1567SHOW client_encoding; 1568</programlisting> 1569 1570 To return to the default encoding: 1571 1572<programlisting> 1573RESET client_encoding; 1574</programlisting> 1575 </para> 1576 </listitem> 1577 1578 <listitem> 1579 <para> 1580 Using <envar>PGCLIENTENCODING</envar>. If the environment variable 1581 <envar>PGCLIENTENCODING</envar> is defined in the client's 1582 environment, that client encoding is automatically selected 1583 when a connection to the server is made. (This can 1584 subsequently be overridden using any of the other methods 1585 mentioned above.) 1586 </para> 1587 </listitem> 1588 1589 <listitem> 1590 <para> 1591 Using the configuration variable <xref 1592 linkend="guc-client-encoding"/>. If the 1593 <varname>client_encoding</varname> variable is set, that client 1594 encoding is automatically selected when a connection to the 1595 server is made. (This can subsequently be overridden using any 1596 of the other methods mentioned above.) 1597 </para> 1598 </listitem> 1599 1600 </itemizedlist> 1601 </para> 1602 1603 <para> 1604 If the conversion of a particular character is not possible 1605 — suppose you chose <literal>EUC_JP</literal> for the 1606 server and <literal>LATIN1</literal> for the client, and some 1607 Japanese characters are returned that do not have a representation in 1608 <literal>LATIN1</literal> — an error is reported. 1609 </para> 1610 1611 <para> 1612 If the client character set is defined as <literal>SQL_ASCII</literal>, 1613 encoding conversion is disabled, regardless of the server's character 1614 set. (However, if the server's character set is 1615 not <literal>SQL_ASCII</literal>, the server will still check that 1616 incoming data is valid for that encoding; so the net effect is as 1617 though the client character set were the same as the server's.) 1618 Just as for the server, use of <literal>SQL_ASCII</literal> is unwise 1619 unless you are working with all-ASCII data. 1620 </para> 1621 </sect2> 1622 1623 <sect2 id="multibyte-conversions-supported"> 1624 <title>Available Character Set Conversions</title> 1625 1626 <para> 1627 <productname>PostgreSQL</productname> allows conversion between any 1628 two character sets for which a conversion function is listed in the 1629 <link linkend="catalog-pg-conversion"><structname>pg_conversion</structname></link> 1630 system catalog. <productname>PostgreSQL</productname> comes with 1631 some predefined conversions, as summarized in 1632 <xref linkend="multibyte-translation-table"/> and shown in more 1633 detail in <xref linkend="builtin-conversions-table"/>. You can 1634 create a new conversion using the SQL command 1635 <xref linkend="sql-createconversion"/>. (To be used for automatic 1636 client/server conversions, a conversion must be marked 1637 as <quote>default</quote> for its character set pair.) 1638 </para> 1639 1640 <table id="multibyte-translation-table"> 1641 <title>Built-in Client/Server Character Set Conversions</title> 1642 <tgroup cols="2"> 1643 <colspec colname="col1" colwidth="1*"/> 1644 <colspec colname="col2" colwidth="3*"/> 1645 <thead> 1646 <row> 1647 <entry>Server Character Set</entry> 1648 <entry>Available Client Character Sets</entry> 1649 </row> 1650 </thead> 1651 <tbody> 1652 <row> 1653 <entry><literal>BIG5</literal></entry> 1654 <entry><emphasis>not supported as a server encoding</emphasis> 1655 </entry> 1656 </row> 1657 <row> 1658 <entry><literal>EUC_CN</literal></entry> 1659 <entry><emphasis>EUC_CN</emphasis>, 1660 <literal>MULE_INTERNAL</literal>, 1661 <literal>UTF8</literal> 1662 </entry> 1663 </row> 1664 <row> 1665 <entry><literal>EUC_JP</literal></entry> 1666 <entry><emphasis>EUC_JP</emphasis>, 1667 <literal>MULE_INTERNAL</literal>, 1668 <literal>SJIS</literal>, 1669 <literal>UTF8</literal> 1670 </entry> 1671 </row> 1672 <row> 1673 <entry><literal>EUC_JIS_2004</literal></entry> 1674 <entry><emphasis>EUC_JIS_2004</emphasis>, 1675 <literal>SHIFT_JIS_2004</literal>, 1676 <literal>UTF8</literal> 1677 </entry> 1678 </row> 1679 <row> 1680 <entry><literal>EUC_KR</literal></entry> 1681 <entry><emphasis>EUC_KR</emphasis>, 1682 <literal>MULE_INTERNAL</literal>, 1683 <literal>UTF8</literal> 1684 </entry> 1685 </row> 1686 <row> 1687 <entry><literal>EUC_TW</literal></entry> 1688 <entry><emphasis>EUC_TW</emphasis>, 1689 <literal>BIG5</literal>, 1690 <literal>MULE_INTERNAL</literal>, 1691 <literal>UTF8</literal> 1692 </entry> 1693 </row> 1694 <row> 1695 <entry><literal>GB18030</literal></entry> 1696 <entry><emphasis>not supported as a server encoding</emphasis> 1697 </entry> 1698 </row> 1699 <row> 1700 <entry><literal>GBK</literal></entry> 1701 <entry><emphasis>not supported as a server encoding</emphasis> 1702 </entry> 1703 </row> 1704 <row> 1705 <entry><literal>ISO_8859_5</literal></entry> 1706 <entry><emphasis>ISO_8859_5</emphasis>, 1707 <literal>KOI8R</literal>, 1708 <literal>MULE_INTERNAL</literal>, 1709 <literal>UTF8</literal>, 1710 <literal>WIN866</literal>, 1711 <literal>WIN1251</literal> 1712 </entry> 1713 </row> 1714 <row> 1715 <entry><literal>ISO_8859_6</literal></entry> 1716 <entry><emphasis>ISO_8859_6</emphasis>, 1717 <literal>UTF8</literal> 1718 </entry> 1719 </row> 1720 <row> 1721 <entry><literal>ISO_8859_7</literal></entry> 1722 <entry><emphasis>ISO_8859_7</emphasis>, 1723 <literal>UTF8</literal> 1724 </entry> 1725 </row> 1726 <row> 1727 <entry><literal>ISO_8859_8</literal></entry> 1728 <entry><emphasis>ISO_8859_8</emphasis>, 1729 <literal>UTF8</literal> 1730 </entry> 1731 </row> 1732 <row> 1733 <entry><literal>JOHAB</literal></entry> 1734 <entry><emphasis>not supported as a server encoding</emphasis> 1735 </entry> 1736 </row> 1737 <row> 1738 <entry><literal>KOI8R</literal></entry> 1739 <entry><emphasis>KOI8R</emphasis>, 1740 <literal>ISO_8859_5</literal>, 1741 <literal>MULE_INTERNAL</literal>, 1742 <literal>UTF8</literal>, 1743 <literal>WIN866</literal>, 1744 <literal>WIN1251</literal> 1745 </entry> 1746 </row> 1747 <row> 1748 <entry><literal>KOI8U</literal></entry> 1749 <entry><emphasis>KOI8U</emphasis>, 1750 <literal>UTF8</literal> 1751 </entry> 1752 </row> 1753 <row> 1754 <entry><literal>LATIN1</literal></entry> 1755 <entry><emphasis>LATIN1</emphasis>, 1756 <literal>MULE_INTERNAL</literal>, 1757 <literal>UTF8</literal> 1758 </entry> 1759 </row> 1760 <row> 1761 <entry><literal>LATIN2</literal></entry> 1762 <entry><emphasis>LATIN2</emphasis>, 1763 <literal>MULE_INTERNAL</literal>, 1764 <literal>UTF8</literal>, 1765 <literal>WIN1250</literal> 1766 </entry> 1767 </row> 1768 <row> 1769 <entry><literal>LATIN3</literal></entry> 1770 <entry><emphasis>LATIN3</emphasis>, 1771 <literal>MULE_INTERNAL</literal>, 1772 <literal>UTF8</literal> 1773 </entry> 1774 </row> 1775 <row> 1776 <entry><literal>LATIN4</literal></entry> 1777 <entry><emphasis>LATIN4</emphasis>, 1778 <literal>MULE_INTERNAL</literal>, 1779 <literal>UTF8</literal> 1780 </entry> 1781 </row> 1782 <row> 1783 <entry><literal>LATIN5</literal></entry> 1784 <entry><emphasis>LATIN5</emphasis>, 1785 <literal>UTF8</literal> 1786 </entry> 1787 </row> 1788 <row> 1789 <entry><literal>LATIN6</literal></entry> 1790 <entry><emphasis>LATIN6</emphasis>, 1791 <literal>UTF8</literal> 1792 </entry> 1793 </row> 1794 <row> 1795 <entry><literal>LATIN7</literal></entry> 1796 <entry><emphasis>LATIN7</emphasis>, 1797 <literal>UTF8</literal> 1798 </entry> 1799 </row> 1800 <row> 1801 <entry><literal>LATIN8</literal></entry> 1802 <entry><emphasis>LATIN8</emphasis>, 1803 <literal>UTF8</literal> 1804 </entry> 1805 </row> 1806 <row> 1807 <entry><literal>LATIN9</literal></entry> 1808 <entry><emphasis>LATIN9</emphasis>, 1809 <literal>UTF8</literal> 1810 </entry> 1811 </row> 1812 <row> 1813 <entry><literal>LATIN10</literal></entry> 1814 <entry><emphasis>LATIN10</emphasis>, 1815 <literal>UTF8</literal> 1816 </entry> 1817 </row> 1818 <row> 1819 <entry><literal>MULE_INTERNAL</literal></entry> 1820 <entry><emphasis>MULE_INTERNAL</emphasis>, 1821 <literal>BIG5</literal>, 1822 <literal>EUC_CN</literal>, 1823 <literal>EUC_JP</literal>, 1824 <literal>EUC_KR</literal>, 1825 <literal>EUC_TW</literal>, 1826 <literal>ISO_8859_5</literal>, 1827 <literal>KOI8R</literal>, 1828 <literal>LATIN1</literal> to <literal>LATIN4</literal>, 1829 <literal>SJIS</literal>, 1830 <literal>WIN866</literal>, 1831 <literal>WIN1250</literal>, 1832 <literal>WIN1251</literal> 1833 </entry> 1834 </row> 1835 <row> 1836 <entry><literal>SJIS</literal></entry> 1837 <entry><emphasis>not supported as a server encoding</emphasis> 1838 </entry> 1839 </row> 1840 <row> 1841 <entry><literal>SHIFT_JIS_2004</literal></entry> 1842 <entry><emphasis>not supported as a server encoding</emphasis> 1843 </entry> 1844 </row> 1845 <row> 1846 <entry><literal>SQL_ASCII</literal></entry> 1847 <entry><emphasis>any (no conversion will be performed)</emphasis> 1848 </entry> 1849 </row> 1850 <row> 1851 <entry><literal>UHC</literal></entry> 1852 <entry><emphasis>not supported as a server encoding</emphasis> 1853 </entry> 1854 </row> 1855 <row> 1856 <entry><literal>UTF8</literal></entry> 1857 <entry><emphasis>all supported encodings</emphasis> 1858 </entry> 1859 </row> 1860 <row> 1861 <entry><literal>WIN866</literal></entry> 1862 <entry><emphasis>WIN866</emphasis>, 1863 <literal>ISO_8859_5</literal>, 1864 <literal>KOI8R</literal>, 1865 <literal>MULE_INTERNAL</literal>, 1866 <literal>UTF8</literal>, 1867 <literal>WIN1251</literal> 1868 </entry> 1869 </row> 1870 <row> 1871 <entry><literal>WIN874</literal></entry> 1872 <entry><emphasis>WIN874</emphasis>, 1873 <literal>UTF8</literal> 1874 </entry> 1875 </row> 1876 <row> 1877 <entry><literal>WIN1250</literal></entry> 1878 <entry><emphasis>WIN1250</emphasis>, 1879 <literal>LATIN2</literal>, 1880 <literal>MULE_INTERNAL</literal>, 1881 <literal>UTF8</literal> 1882 </entry> 1883 </row> 1884 <row> 1885 <entry><literal>WIN1251</literal></entry> 1886 <entry><emphasis>WIN1251</emphasis>, 1887 <literal>ISO_8859_5</literal>, 1888 <literal>KOI8R</literal>, 1889 <literal>MULE_INTERNAL</literal>, 1890 <literal>UTF8</literal>, 1891 <literal>WIN866</literal> 1892 </entry> 1893 </row> 1894 <row> 1895 <entry><literal>WIN1252</literal></entry> 1896 <entry><emphasis>WIN1252</emphasis>, 1897 <literal>UTF8</literal> 1898 </entry> 1899 </row> 1900 <row> 1901 <entry><literal>WIN1253</literal></entry> 1902 <entry><emphasis>WIN1253</emphasis>, 1903 <literal>UTF8</literal> 1904 </entry> 1905 </row> 1906 <row> 1907 <entry><literal>WIN1254</literal></entry> 1908 <entry><emphasis>WIN1254</emphasis>, 1909 <literal>UTF8</literal> 1910 </entry> 1911 </row> 1912 <row> 1913 <entry><literal>WIN1255</literal></entry> 1914 <entry><emphasis>WIN1255</emphasis>, 1915 <literal>UTF8</literal> 1916 </entry> 1917 </row> 1918 <row> 1919 <entry><literal>WIN1256</literal></entry> 1920 <entry><emphasis>WIN1256</emphasis>, 1921 <literal>UTF8</literal> 1922 </entry> 1923 </row> 1924 <row> 1925 <entry><literal>WIN1257</literal></entry> 1926 <entry><emphasis>WIN1257</emphasis>, 1927 <literal>UTF8</literal> 1928 </entry> 1929 </row> 1930 <row> 1931 <entry><literal>WIN1258</literal></entry> 1932 <entry><emphasis>WIN1258</emphasis>, 1933 <literal>UTF8</literal> 1934 </entry> 1935 </row> 1936 </tbody> 1937 </tgroup> 1938 </table> 1939 1940 <table id="builtin-conversions-table"> 1941 <title>All Built-in Character Set Conversions</title> 1942 <tgroup cols="3"> 1943 <colspec colname="col1" colwidth="2*"/> 1944 <colspec colname="col2" colwidth="1*"/> 1945 <colspec colname="col3" colwidth="1*"/> 1946 <thead> 1947 <row> 1948 <entry>Conversion Name 1949 <footnote> 1950 <para> 1951 The conversion names follow a standard naming scheme: The 1952 official name of the source encoding with all 1953 non-alphanumeric characters replaced by underscores, followed 1954 by <literal>_to_</literal>, followed by the similarly processed 1955 destination encoding name. Therefore, these names sometimes 1956 deviate from the customary encoding names shown in 1957 <xref linkend="charset-table"/>. 1958 </para> 1959 </footnote> 1960 </entry> 1961 <entry>Source Encoding</entry> 1962 <entry>Destination Encoding</entry> 1963 </row> 1964 </thead> 1965 1966 <tbody> 1967 <row> 1968 <entry><literal>big5_to_euc_tw</literal></entry> 1969 <entry><literal>BIG5</literal></entry> 1970 <entry><literal>EUC_TW</literal></entry> 1971 </row> 1972 <row> 1973 <entry><literal>big5_to_mic</literal></entry> 1974 <entry><literal>BIG5</literal></entry> 1975 <entry><literal>MULE_INTERNAL</literal></entry> 1976 </row> 1977 <row> 1978 <entry><literal>big5_to_utf8</literal></entry> 1979 <entry><literal>BIG5</literal></entry> 1980 <entry><literal>UTF8</literal></entry> 1981 </row> 1982 <row> 1983 <entry><literal>euc_cn_to_mic</literal></entry> 1984 <entry><literal>EUC_CN</literal></entry> 1985 <entry><literal>MULE_INTERNAL</literal></entry> 1986 </row> 1987 <row> 1988 <entry><literal>euc_cn_to_utf8</literal></entry> 1989 <entry><literal>EUC_CN</literal></entry> 1990 <entry><literal>UTF8</literal></entry> 1991 </row> 1992 <row> 1993 <entry><literal>euc_jp_to_mic</literal></entry> 1994 <entry><literal>EUC_JP</literal></entry> 1995 <entry><literal>MULE_INTERNAL</literal></entry> 1996 </row> 1997 <row> 1998 <entry><literal>euc_jp_to_sjis</literal></entry> 1999 <entry><literal>EUC_JP</literal></entry> 2000 <entry><literal>SJIS</literal></entry> 2001 </row> 2002 <row> 2003 <entry><literal>euc_jp_to_utf8</literal></entry> 2004 <entry><literal>EUC_JP</literal></entry> 2005 <entry><literal>UTF8</literal></entry> 2006 </row> 2007 <row> 2008 <entry><literal>euc_kr_to_mic</literal></entry> 2009 <entry><literal>EUC_KR</literal></entry> 2010 <entry><literal>MULE_INTERNAL</literal></entry> 2011 </row> 2012 <row> 2013 <entry><literal>euc_kr_to_utf8</literal></entry> 2014 <entry><literal>EUC_KR</literal></entry> 2015 <entry><literal>UTF8</literal></entry> 2016 </row> 2017 <row> 2018 <entry><literal>euc_tw_to_big5</literal></entry> 2019 <entry><literal>EUC_TW</literal></entry> 2020 <entry><literal>BIG5</literal></entry> 2021 </row> 2022 <row> 2023 <entry><literal>euc_tw_to_mic</literal></entry> 2024 <entry><literal>EUC_TW</literal></entry> 2025 <entry><literal>MULE_INTERNAL</literal></entry> 2026 </row> 2027 <row> 2028 <entry><literal>euc_tw_to_utf8</literal></entry> 2029 <entry><literal>EUC_TW</literal></entry> 2030 <entry><literal>UTF8</literal></entry> 2031 </row> 2032 <row> 2033 <entry><literal>gb18030_to_utf8</literal></entry> 2034 <entry><literal>GB18030</literal></entry> 2035 <entry><literal>UTF8</literal></entry> 2036 </row> 2037 <row> 2038 <entry><literal>gbk_to_utf8</literal></entry> 2039 <entry><literal>GBK</literal></entry> 2040 <entry><literal>UTF8</literal></entry> 2041 </row> 2042 <row> 2043 <entry><literal>iso_8859_10_to_utf8</literal></entry> 2044 <entry><literal>LATIN6</literal></entry> 2045 <entry><literal>UTF8</literal></entry> 2046 </row> 2047 <row> 2048 <entry><literal>iso_8859_13_to_utf8</literal></entry> 2049 <entry><literal>LATIN7</literal></entry> 2050 <entry><literal>UTF8</literal></entry> 2051 </row> 2052 <row> 2053 <entry><literal>iso_8859_14_to_utf8</literal></entry> 2054 <entry><literal>LATIN8</literal></entry> 2055 <entry><literal>UTF8</literal></entry> 2056 </row> 2057 <row> 2058 <entry><literal>iso_8859_15_to_utf8</literal></entry> 2059 <entry><literal>LATIN9</literal></entry> 2060 <entry><literal>UTF8</literal></entry> 2061 </row> 2062 <row> 2063 <entry><literal>iso_8859_16_to_utf8</literal></entry> 2064 <entry><literal>LATIN10</literal></entry> 2065 <entry><literal>UTF8</literal></entry> 2066 </row> 2067 <row> 2068 <entry><literal>iso_8859_1_to_mic</literal></entry> 2069 <entry><literal>LATIN1</literal></entry> 2070 <entry><literal>MULE_INTERNAL</literal></entry> 2071 </row> 2072 <row> 2073 <entry><literal>iso_8859_1_to_utf8</literal></entry> 2074 <entry><literal>LATIN1</literal></entry> 2075 <entry><literal>UTF8</literal></entry> 2076 </row> 2077 <row> 2078 <entry><literal>iso_8859_2_to_mic</literal></entry> 2079 <entry><literal>LATIN2</literal></entry> 2080 <entry><literal>MULE_INTERNAL</literal></entry> 2081 </row> 2082 <row> 2083 <entry><literal>iso_8859_2_to_utf8</literal></entry> 2084 <entry><literal>LATIN2</literal></entry> 2085 <entry><literal>UTF8</literal></entry> 2086 </row> 2087 <row> 2088 <entry><literal>iso_8859_2_to_windows_1250</literal></entry> 2089 <entry><literal>LATIN2</literal></entry> 2090 <entry><literal>WIN1250</literal></entry> 2091 </row> 2092 <row> 2093 <entry><literal>iso_8859_3_to_mic</literal></entry> 2094 <entry><literal>LATIN3</literal></entry> 2095 <entry><literal>MULE_INTERNAL</literal></entry> 2096 </row> 2097 <row> 2098 <entry><literal>iso_8859_3_to_utf8</literal></entry> 2099 <entry><literal>LATIN3</literal></entry> 2100 <entry><literal>UTF8</literal></entry> 2101 </row> 2102 <row> 2103 <entry><literal>iso_8859_4_to_mic</literal></entry> 2104 <entry><literal>LATIN4</literal></entry> 2105 <entry><literal>MULE_INTERNAL</literal></entry> 2106 </row> 2107 <row> 2108 <entry><literal>iso_8859_4_to_utf8</literal></entry> 2109 <entry><literal>LATIN4</literal></entry> 2110 <entry><literal>UTF8</literal></entry> 2111 </row> 2112 <row> 2113 <entry><literal>iso_8859_5_to_koi8_r</literal></entry> 2114 <entry><literal>ISO_8859_5</literal></entry> 2115 <entry><literal>KOI8R</literal></entry> 2116 </row> 2117 <row> 2118 <entry><literal>iso_8859_5_to_mic</literal></entry> 2119 <entry><literal>ISO_8859_5</literal></entry> 2120 <entry><literal>MULE_INTERNAL</literal></entry> 2121 </row> 2122 <row> 2123 <entry><literal>iso_8859_5_to_utf8</literal></entry> 2124 <entry><literal>ISO_8859_5</literal></entry> 2125 <entry><literal>UTF8</literal></entry> 2126 </row> 2127 <row> 2128 <entry><literal>iso_8859_5_to_windows_1251</literal></entry> 2129 <entry><literal>ISO_8859_5</literal></entry> 2130 <entry><literal>WIN1251</literal></entry> 2131 </row> 2132 <row> 2133 <entry><literal>iso_8859_5_to_windows_866</literal></entry> 2134 <entry><literal>ISO_8859_5</literal></entry> 2135 <entry><literal>WIN866</literal></entry> 2136 </row> 2137 <row> 2138 <entry><literal>iso_8859_6_to_utf8</literal></entry> 2139 <entry><literal>ISO_8859_6</literal></entry> 2140 <entry><literal>UTF8</literal></entry> 2141 </row> 2142 <row> 2143 <entry><literal>iso_8859_7_to_utf8</literal></entry> 2144 <entry><literal>ISO_8859_7</literal></entry> 2145 <entry><literal>UTF8</literal></entry> 2146 </row> 2147 <row> 2148 <entry><literal>iso_8859_8_to_utf8</literal></entry> 2149 <entry><literal>ISO_8859_8</literal></entry> 2150 <entry><literal>UTF8</literal></entry> 2151 </row> 2152 <row> 2153 <entry><literal>iso_8859_9_to_utf8</literal></entry> 2154 <entry><literal>LATIN5</literal></entry> 2155 <entry><literal>UTF8</literal></entry> 2156 </row> 2157 <row> 2158 <entry><literal>johab_to_utf8</literal></entry> 2159 <entry><literal>JOHAB</literal></entry> 2160 <entry><literal>UTF8</literal></entry> 2161 </row> 2162 <row> 2163 <entry><literal>koi8_r_to_iso_8859_5</literal></entry> 2164 <entry><literal>KOI8R</literal></entry> 2165 <entry><literal>ISO_8859_5</literal></entry> 2166 </row> 2167 <row> 2168 <entry><literal>koi8_r_to_mic</literal></entry> 2169 <entry><literal>KOI8R</literal></entry> 2170 <entry><literal>MULE_INTERNAL</literal></entry> 2171 </row> 2172 <row> 2173 <entry><literal>koi8_r_to_utf8</literal></entry> 2174 <entry><literal>KOI8R</literal></entry> 2175 <entry><literal>UTF8</literal></entry> 2176 </row> 2177 <row> 2178 <entry><literal>koi8_r_to_windows_1251</literal></entry> 2179 <entry><literal>KOI8R</literal></entry> 2180 <entry><literal>WIN1251</literal></entry> 2181 </row> 2182 <row> 2183 <entry><literal>koi8_r_to_windows_866</literal></entry> 2184 <entry><literal>KOI8R</literal></entry> 2185 <entry><literal>WIN866</literal></entry> 2186 </row> 2187 <row> 2188 <entry><literal>koi8_u_to_utf8</literal></entry> 2189 <entry><literal>KOI8U</literal></entry> 2190 <entry><literal>UTF8</literal></entry> 2191 </row> 2192 <row> 2193 <entry><literal>mic_to_big5</literal></entry> 2194 <entry><literal>MULE_INTERNAL</literal></entry> 2195 <entry><literal>BIG5</literal></entry> 2196 </row> 2197 <row> 2198 <entry><literal>mic_to_euc_cn</literal></entry> 2199 <entry><literal>MULE_INTERNAL</literal></entry> 2200 <entry><literal>EUC_CN</literal></entry> 2201 </row> 2202 <row> 2203 <entry><literal>mic_to_euc_jp</literal></entry> 2204 <entry><literal>MULE_INTERNAL</literal></entry> 2205 <entry><literal>EUC_JP</literal></entry> 2206 </row> 2207 <row> 2208 <entry><literal>mic_to_euc_kr</literal></entry> 2209 <entry><literal>MULE_INTERNAL</literal></entry> 2210 <entry><literal>EUC_KR</literal></entry> 2211 </row> 2212 <row> 2213 <entry><literal>mic_to_euc_tw</literal></entry> 2214 <entry><literal>MULE_INTERNAL</literal></entry> 2215 <entry><literal>EUC_TW</literal></entry> 2216 </row> 2217 <row> 2218 <entry><literal>mic_to_iso_8859_1</literal></entry> 2219 <entry><literal>MULE_INTERNAL</literal></entry> 2220 <entry><literal>LATIN1</literal></entry> 2221 </row> 2222 <row> 2223 <entry><literal>mic_to_iso_8859_2</literal></entry> 2224 <entry><literal>MULE_INTERNAL</literal></entry> 2225 <entry><literal>LATIN2</literal></entry> 2226 </row> 2227 <row> 2228 <entry><literal>mic_to_iso_8859_3</literal></entry> 2229 <entry><literal>MULE_INTERNAL</literal></entry> 2230 <entry><literal>LATIN3</literal></entry> 2231 </row> 2232 <row> 2233 <entry><literal>mic_to_iso_8859_4</literal></entry> 2234 <entry><literal>MULE_INTERNAL</literal></entry> 2235 <entry><literal>LATIN4</literal></entry> 2236 </row> 2237 <row> 2238 <entry><literal>mic_to_iso_8859_5</literal></entry> 2239 <entry><literal>MULE_INTERNAL</literal></entry> 2240 <entry><literal>ISO_8859_5</literal></entry> 2241 </row> 2242 <row> 2243 <entry><literal>mic_to_koi8_r</literal></entry> 2244 <entry><literal>MULE_INTERNAL</literal></entry> 2245 <entry><literal>KOI8R</literal></entry> 2246 </row> 2247 <row> 2248 <entry><literal>mic_to_sjis</literal></entry> 2249 <entry><literal>MULE_INTERNAL</literal></entry> 2250 <entry><literal>SJIS</literal></entry> 2251 </row> 2252 <row> 2253 <entry><literal>mic_to_windows_1250</literal></entry> 2254 <entry><literal>MULE_INTERNAL</literal></entry> 2255 <entry><literal>WIN1250</literal></entry> 2256 </row> 2257 <row> 2258 <entry><literal>mic_to_windows_1251</literal></entry> 2259 <entry><literal>MULE_INTERNAL</literal></entry> 2260 <entry><literal>WIN1251</literal></entry> 2261 </row> 2262 <row> 2263 <entry><literal>mic_to_windows_866</literal></entry> 2264 <entry><literal>MULE_INTERNAL</literal></entry> 2265 <entry><literal>WIN866</literal></entry> 2266 </row> 2267 <row> 2268 <entry><literal>sjis_to_euc_jp</literal></entry> 2269 <entry><literal>SJIS</literal></entry> 2270 <entry><literal>EUC_JP</literal></entry> 2271 </row> 2272 <row> 2273 <entry><literal>sjis_to_mic</literal></entry> 2274 <entry><literal>SJIS</literal></entry> 2275 <entry><literal>MULE_INTERNAL</literal></entry> 2276 </row> 2277 <row> 2278 <entry><literal>sjis_to_utf8</literal></entry> 2279 <entry><literal>SJIS</literal></entry> 2280 <entry><literal>UTF8</literal></entry> 2281 </row> 2282 <row> 2283 <entry><literal>windows_1258_to_utf8</literal></entry> 2284 <entry><literal>WIN1258</literal></entry> 2285 <entry><literal>UTF8</literal></entry> 2286 </row> 2287 <row> 2288 <entry><literal>uhc_to_utf8</literal></entry> 2289 <entry><literal>UHC</literal></entry> 2290 <entry><literal>UTF8</literal></entry> 2291 </row> 2292 <row> 2293 <entry><literal>utf8_to_big5</literal></entry> 2294 <entry><literal>UTF8</literal></entry> 2295 <entry><literal>BIG5</literal></entry> 2296 </row> 2297 <row> 2298 <entry><literal>utf8_to_euc_cn</literal></entry> 2299 <entry><literal>UTF8</literal></entry> 2300 <entry><literal>EUC_CN</literal></entry> 2301 </row> 2302 <row> 2303 <entry><literal>utf8_to_euc_jp</literal></entry> 2304 <entry><literal>UTF8</literal></entry> 2305 <entry><literal>EUC_JP</literal></entry> 2306 </row> 2307 <row> 2308 <entry><literal>utf8_to_euc_kr</literal></entry> 2309 <entry><literal>UTF8</literal></entry> 2310 <entry><literal>EUC_KR</literal></entry> 2311 </row> 2312 <row> 2313 <entry><literal>utf8_to_euc_tw</literal></entry> 2314 <entry><literal>UTF8</literal></entry> 2315 <entry><literal>EUC_TW</literal></entry> 2316 </row> 2317 <row> 2318 <entry><literal>utf8_to_gb18030</literal></entry> 2319 <entry><literal>UTF8</literal></entry> 2320 <entry><literal>GB18030</literal></entry> 2321 </row> 2322 <row> 2323 <entry><literal>utf8_to_gbk</literal></entry> 2324 <entry><literal>UTF8</literal></entry> 2325 <entry><literal>GBK</literal></entry> 2326 </row> 2327 <row> 2328 <entry><literal>utf8_to_iso_8859_1</literal></entry> 2329 <entry><literal>UTF8</literal></entry> 2330 <entry><literal>LATIN1</literal></entry> 2331 </row> 2332 <row> 2333 <entry><literal>utf8_to_iso_8859_10</literal></entry> 2334 <entry><literal>UTF8</literal></entry> 2335 <entry><literal>LATIN6</literal></entry> 2336 </row> 2337 <row> 2338 <entry><literal>utf8_to_iso_8859_13</literal></entry> 2339 <entry><literal>UTF8</literal></entry> 2340 <entry><literal>LATIN7</literal></entry> 2341 </row> 2342 <row> 2343 <entry><literal>utf8_to_iso_8859_14</literal></entry> 2344 <entry><literal>UTF8</literal></entry> 2345 <entry><literal>LATIN8</literal></entry> 2346 </row> 2347 <row> 2348 <entry><literal>utf8_to_iso_8859_15</literal></entry> 2349 <entry><literal>UTF8</literal></entry> 2350 <entry><literal>LATIN9</literal></entry> 2351 </row> 2352 <row> 2353 <entry><literal>utf8_to_iso_8859_16</literal></entry> 2354 <entry><literal>UTF8</literal></entry> 2355 <entry><literal>LATIN10</literal></entry> 2356 </row> 2357 <row> 2358 <entry><literal>utf8_to_iso_8859_2</literal></entry> 2359 <entry><literal>UTF8</literal></entry> 2360 <entry><literal>LATIN2</literal></entry> 2361 </row> 2362 <row> 2363 <entry><literal>utf8_to_iso_8859_3</literal></entry> 2364 <entry><literal>UTF8</literal></entry> 2365 <entry><literal>LATIN3</literal></entry> 2366 </row> 2367 <row> 2368 <entry><literal>utf8_to_iso_8859_4</literal></entry> 2369 <entry><literal>UTF8</literal></entry> 2370 <entry><literal>LATIN4</literal></entry> 2371 </row> 2372 <row> 2373 <entry><literal>utf8_to_iso_8859_5</literal></entry> 2374 <entry><literal>UTF8</literal></entry> 2375 <entry><literal>ISO_8859_5</literal></entry> 2376 </row> 2377 <row> 2378 <entry><literal>utf8_to_iso_8859_6</literal></entry> 2379 <entry><literal>UTF8</literal></entry> 2380 <entry><literal>ISO_8859_6</literal></entry> 2381 </row> 2382 <row> 2383 <entry><literal>utf8_to_iso_8859_7</literal></entry> 2384 <entry><literal>UTF8</literal></entry> 2385 <entry><literal>ISO_8859_7</literal></entry> 2386 </row> 2387 <row> 2388 <entry><literal>utf8_to_iso_8859_8</literal></entry> 2389 <entry><literal>UTF8</literal></entry> 2390 <entry><literal>ISO_8859_8</literal></entry> 2391 </row> 2392 <row> 2393 <entry><literal>utf8_to_iso_8859_9</literal></entry> 2394 <entry><literal>UTF8</literal></entry> 2395 <entry><literal>LATIN5</literal></entry> 2396 </row> 2397 <row> 2398 <entry><literal>utf8_to_johab</literal></entry> 2399 <entry><literal>UTF8</literal></entry> 2400 <entry><literal>JOHAB</literal></entry> 2401 </row> 2402 <row> 2403 <entry><literal>utf8_to_koi8_r</literal></entry> 2404 <entry><literal>UTF8</literal></entry> 2405 <entry><literal>KOI8R</literal></entry> 2406 </row> 2407 <row> 2408 <entry><literal>utf8_to_koi8_u</literal></entry> 2409 <entry><literal>UTF8</literal></entry> 2410 <entry><literal>KOI8U</literal></entry> 2411 </row> 2412 <row> 2413 <entry><literal>utf8_to_sjis</literal></entry> 2414 <entry><literal>UTF8</literal></entry> 2415 <entry><literal>SJIS</literal></entry> 2416 </row> 2417 <row> 2418 <entry><literal>utf8_to_windows_1258</literal></entry> 2419 <entry><literal>UTF8</literal></entry> 2420 <entry><literal>WIN1258</literal></entry> 2421 </row> 2422 <row> 2423 <entry><literal>utf8_to_uhc</literal></entry> 2424 <entry><literal>UTF8</literal></entry> 2425 <entry><literal>UHC</literal></entry> 2426 </row> 2427 <row> 2428 <entry><literal>utf8_to_windows_1250</literal></entry> 2429 <entry><literal>UTF8</literal></entry> 2430 <entry><literal>WIN1250</literal></entry> 2431 </row> 2432 <row> 2433 <entry><literal>utf8_to_windows_1251</literal></entry> 2434 <entry><literal>UTF8</literal></entry> 2435 <entry><literal>WIN1251</literal></entry> 2436 </row> 2437 <row> 2438 <entry><literal>utf8_to_windows_1252</literal></entry> 2439 <entry><literal>UTF8</literal></entry> 2440 <entry><literal>WIN1252</literal></entry> 2441 </row> 2442 <row> 2443 <entry><literal>utf8_to_windows_1253</literal></entry> 2444 <entry><literal>UTF8</literal></entry> 2445 <entry><literal>WIN1253</literal></entry> 2446 </row> 2447 <row> 2448 <entry><literal>utf8_to_windows_1254</literal></entry> 2449 <entry><literal>UTF8</literal></entry> 2450 <entry><literal>WIN1254</literal></entry> 2451 </row> 2452 <row> 2453 <entry><literal>utf8_to_windows_1255</literal></entry> 2454 <entry><literal>UTF8</literal></entry> 2455 <entry><literal>WIN1255</literal></entry> 2456 </row> 2457 <row> 2458 <entry><literal>utf8_to_windows_1256</literal></entry> 2459 <entry><literal>UTF8</literal></entry> 2460 <entry><literal>WIN1256</literal></entry> 2461 </row> 2462 <row> 2463 <entry><literal>utf8_to_windows_1257</literal></entry> 2464 <entry><literal>UTF8</literal></entry> 2465 <entry><literal>WIN1257</literal></entry> 2466 </row> 2467 <row> 2468 <entry><literal>utf8_to_windows_866</literal></entry> 2469 <entry><literal>UTF8</literal></entry> 2470 <entry><literal>WIN866</literal></entry> 2471 </row> 2472 <row> 2473 <entry><literal>utf8_to_windows_874</literal></entry> 2474 <entry><literal>UTF8</literal></entry> 2475 <entry><literal>WIN874</literal></entry> 2476 </row> 2477 <row> 2478 <entry><literal>windows_1250_to_iso_8859_2</literal></entry> 2479 <entry><literal>WIN1250</literal></entry> 2480 <entry><literal>LATIN2</literal></entry> 2481 </row> 2482 <row> 2483 <entry><literal>windows_1250_to_mic</literal></entry> 2484 <entry><literal>WIN1250</literal></entry> 2485 <entry><literal>MULE_INTERNAL</literal></entry> 2486 </row> 2487 <row> 2488 <entry><literal>windows_1250_to_utf8</literal></entry> 2489 <entry><literal>WIN1250</literal></entry> 2490 <entry><literal>UTF8</literal></entry> 2491 </row> 2492 <row> 2493 <entry><literal>windows_1251_to_iso_8859_5</literal></entry> 2494 <entry><literal>WIN1251</literal></entry> 2495 <entry><literal>ISO_8859_5</literal></entry> 2496 </row> 2497 <row> 2498 <entry><literal>windows_1251_to_koi8_r</literal></entry> 2499 <entry><literal>WIN1251</literal></entry> 2500 <entry><literal>KOI8R</literal></entry> 2501 </row> 2502 <row> 2503 <entry><literal>windows_1251_to_mic</literal></entry> 2504 <entry><literal>WIN1251</literal></entry> 2505 <entry><literal>MULE_INTERNAL</literal></entry> 2506 </row> 2507 <row> 2508 <entry><literal>windows_1251_to_utf8</literal></entry> 2509 <entry><literal>WIN1251</literal></entry> 2510 <entry><literal>UTF8</literal></entry> 2511 </row> 2512 <row> 2513 <entry><literal>windows_1251_to_windows_866</literal></entry> 2514 <entry><literal>WIN1251</literal></entry> 2515 <entry><literal>WIN866</literal></entry> 2516 </row> 2517 <row> 2518 <entry><literal>windows_1252_to_utf8</literal></entry> 2519 <entry><literal>WIN1252</literal></entry> 2520 <entry><literal>UTF8</literal></entry> 2521 </row> 2522 <row> 2523 <entry><literal>windows_1256_to_utf8</literal></entry> 2524 <entry><literal>WIN1256</literal></entry> 2525 <entry><literal>UTF8</literal></entry> 2526 </row> 2527 <row> 2528 <entry><literal>windows_866_to_iso_8859_5</literal></entry> 2529 <entry><literal>WIN866</literal></entry> 2530 <entry><literal>ISO_8859_5</literal></entry> 2531 </row> 2532 <row> 2533 <entry><literal>windows_866_to_koi8_r</literal></entry> 2534 <entry><literal>WIN866</literal></entry> 2535 <entry><literal>KOI8R</literal></entry> 2536 </row> 2537 <row> 2538 <entry><literal>windows_866_to_mic</literal></entry> 2539 <entry><literal>WIN866</literal></entry> 2540 <entry><literal>MULE_INTERNAL</literal></entry> 2541 </row> 2542 <row> 2543 <entry><literal>windows_866_to_utf8</literal></entry> 2544 <entry><literal>WIN866</literal></entry> 2545 <entry><literal>UTF8</literal></entry> 2546 </row> 2547 <row> 2548 <entry><literal>windows_866_to_windows_1251</literal></entry> 2549 <entry><literal>WIN866</literal></entry> 2550 <entry><literal>WIN</literal></entry> 2551 </row> 2552 <row> 2553 <entry><literal>windows_874_to_utf8</literal></entry> 2554 <entry><literal>WIN874</literal></entry> 2555 <entry><literal>UTF8</literal></entry> 2556 </row> 2557 <row> 2558 <entry><literal>euc_jis_2004_to_utf8</literal></entry> 2559 <entry><literal>EUC_JIS_2004</literal></entry> 2560 <entry><literal>UTF8</literal></entry> 2561 </row> 2562 <row> 2563 <entry><literal>utf8_to_euc_jis_2004</literal></entry> 2564 <entry><literal>UTF8</literal></entry> 2565 <entry><literal>EUC_JIS_2004</literal></entry> 2566 </row> 2567 <row> 2568 <entry><literal>shift_jis_2004_to_utf8</literal></entry> 2569 <entry><literal>SHIFT_JIS_2004</literal></entry> 2570 <entry><literal>UTF8</literal></entry> 2571 </row> 2572 <row> 2573 <entry><literal>utf8_to_shift_jis_2004</literal></entry> 2574 <entry><literal>UTF8</literal></entry> 2575 <entry><literal>SHIFT_JIS_2004</literal></entry> 2576 </row> 2577 <row> 2578 <entry><literal>euc_jis_2004_to_shift_jis_2004</literal></entry> 2579 <entry><literal>EUC_JIS_2004</literal></entry> 2580 <entry><literal>SHIFT_JIS_2004</literal></entry> 2581 </row> 2582 <row> 2583 <entry><literal>shift_jis_2004_to_euc_jis_2004</literal></entry> 2584 <entry><literal>SHIFT_JIS_2004</literal></entry> 2585 <entry><literal>EUC_JIS_2004</literal></entry> 2586 </row> 2587 </tbody> 2588 </tgroup> 2589 </table> 2590 </sect2> 2591 2592 <sect2> 2593 <title>Further Reading</title> 2594 2595 <para> 2596 These are good sources to start learning about various kinds of encoding 2597 systems. 2598 2599 <variablelist> 2600 <varlistentry> 2601 <term><citetitle>CJKV Information Processing: Chinese, Japanese, Korean & Vietnamese Computing</citetitle></term> 2602 2603 <listitem> 2604 <para> 2605 Contains detailed explanations of <literal>EUC_JP</literal>, 2606 <literal>EUC_CN</literal>, <literal>EUC_KR</literal>, 2607 <literal>EUC_TW</literal>. 2608 </para> 2609 </listitem> 2610 </varlistentry> 2611 2612 <varlistentry> 2613 <term><ulink url="https://www.unicode.org/"></ulink></term> 2614 2615 <listitem> 2616 <para> 2617 The web site of the Unicode Consortium. 2618 </para> 2619 </listitem> 2620 </varlistentry> 2621 2622 <varlistentry> 2623 <term>RFC 3629</term> 2624 2625 <listitem> 2626 <para> 2627 <acronym>UTF</acronym>-8 (8-bit UCS/Unicode Transformation 2628 Format) is defined here. 2629 </para> 2630 </listitem> 2631 </varlistentry> 2632 </variablelist> 2633 </para> 2634 </sect2> 2635 2636 </sect1> 2637 2638</chapter> 2639