> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/server-administration/charset/multibyte.md). # 23.3. Character Set Support \# [23.3.1. Supported Character Sets](#MULTIBYTE-CHARSET-SUPPORTED) [23.3.2. Setting the Character Set](#MULTIBYTE-SETTING) [23.3.3. Automatic Character Set Conversion Between Server and Client](#MULTIBYTE-AUTOMATIC-CONVERSION) [23.3.4. Available Character Set Conversions](#MULTIBYTE-CONVERSIONS-SUPPORTED) [23.3.5. Further Reading](#MULTIBYTE-FURTHER-READING) The character set support in PostgreSQL allows you to store text in a variety of character sets (also called encodings), including single-byte character sets such as the ISO 8859 series and multiple-byte character sets such as EUC (Extended Unix Code), UTF-8, and Mule internal code. All supported character sets can be used transparently by clients, but a few are not supported for use within the server (that is, as a server-side encoding). The default character set is selected while initializing your PostgreSQL database cluster using `initdb`. It can be overridden when you create a database, so you can have multiple databases each with a different character set. An important restriction, however, is that each database's character set must be compatible with the database's `LC_CTYPE` (character classification) and `LC_COLLATE` (string sort order) locale settings. For `C` or `POSIX` locale, any character set is allowed, but for other libc-provided locales there is only one character set that will work correctly. (On Windows, however, UTF-8 encoding can be used with any locale.) If you have ICU support configured, ICU-provided locales can be used with most but not all server-side encodings. ## 23.3.1. Supported Character Sets [#](#MULTIBYTE-CHARSET-SUPPORTED) [Table 23.3](#CHARSET-TABLE) shows the character sets available for use in PostgreSQL. **Table 23.3. PostgreSQL Character Sets** | Name | Description | Language | Server? | ICU? | Bytes/​Char | Aliases | | ---------------- | --------------------------------- | ------------------------------ | ------- | ---- | ----------- | --------------------------------------------- | | `BIG5` | Big Five | Traditional Chinese | No | No | 1–2 | `WIN950`, `Windows950` | | `EUC_CN` | Extended UNIX Code-CN | Simplified Chinese | Yes | Yes | 1–3 | | | `EUC_JP` | Extended UNIX Code-JP | Japanese | Yes | Yes | 1–3 | | | `EUC_JIS_2004` | Extended UNIX Code-JP, JIS X 0213 | Japanese | Yes | No | 1–3 | | | `EUC_KR` | Extended UNIX Code-KR | Korean | Yes | Yes | 1–3 | | | `EUC_TW` | Extended UNIX Code-TW | Traditional Chinese, Taiwanese | Yes | Yes | 1–4 | | | `GB18030` | National Standard | Chinese | No | No | 1–4 | | | `GBK` | Extended National Standard | Simplified Chinese | No | No | 1–2 | `WIN936`, `Windows936` | | `ISO_8859_5` | ISO 8859-5, ECMA 113 | Latin/Cyrillic | Yes | Yes | 1 | | | `ISO_8859_6` | ISO 8859-6, ECMA 114 | Latin/Arabic | Yes | Yes | 1 | | | `ISO_8859_7` | ISO 8859-7, ECMA 118 | Latin/Greek | Yes | Yes | 1 | | | `ISO_8859_8` | ISO 8859-8, ECMA 121 | Latin/Hebrew | Yes | Yes | 1 | | | `JOHAB` | JOHAB | Korean (Hangul) | No | No | 1–3 | | | `KOI8R` | KOI8-R | Cyrillic (Russian) | Yes | Yes | 1 | `KOI8` | | `KOI8U` | KOI8-U | Cyrillic (Ukrainian) | Yes | Yes | 1 | | | `LATIN1` | ISO 8859-1, ECMA 94 | Western European | Yes | Yes | 1 | `ISO88591` | | `LATIN2` | ISO 8859-2, ECMA 94 | Central European | Yes | Yes | 1 | `ISO88592` | | `LATIN3` | ISO 8859-3, ECMA 94 | South European | Yes | Yes | 1 | `ISO88593` | | `LATIN4` | ISO 8859-4, ECMA 94 | North European | Yes | Yes | 1 | `ISO88594` | | `LATIN5` | ISO 8859-9, ECMA 128 | Turkish | Yes | Yes | 1 | `ISO88599` | | `LATIN6` | ISO 8859-10, ECMA 144 | Nordic | Yes | Yes | 1 | `ISO885910` | | `LATIN7` | ISO 8859-13 | Baltic | Yes | Yes | 1 | `ISO885913` | | `LATIN8` | ISO 8859-14 | Celtic | Yes | Yes | 1 | `ISO885914` | | `LATIN9` | ISO 8859-15 | LATIN1 with Euro and accents | Yes | Yes | 1 | `ISO885915` | | `LATIN10` | ISO 8859-16, ASRO SR 14111 | Romanian | Yes | No | 1 | `ISO885916` | | `MULE_INTERNAL` | Mule internal code | Multilingual Emacs | Yes | No | 1–4 | | | `SJIS` | Shift JIS | Japanese | No | No | 1–2 | `Mskanji`, `ShiftJIS`, `WIN932`, `Windows932` | | `SHIFT_JIS_2004` | Shift JIS, JIS X 0213 | Japanese | No | No | 1–2 | | | `SQL_ASCII` | unspecified (see text) | *any* | Yes | No | 1 | | | `UHC` | Unified Hangul Code | Korean | No | No | 1–2 | `WIN949`, `Windows949` | | `UTF8` | Unicode, 8-bit | *all* | Yes | Yes | 1–4 | `Unicode` | | `WIN866` | Windows CP866 | Cyrillic | Yes | Yes | 1 | `ALT` | | `WIN874` | Windows CP874 | Thai | Yes | No | 1 | | | `WIN1250` | Windows CP1250 | Central European | Yes | Yes | 1 | | | `WIN1251` | Windows CP1251 | Cyrillic | Yes | Yes | 1 | `WIN` | | `WIN1252` | Windows CP1252 | Western European | Yes | Yes | 1 | | | `WIN1253` | Windows CP1253 | Greek | Yes | Yes | 1 | | | `WIN1254` | Windows CP1254 | Turkish | Yes | Yes | 1 | | | `WIN1255` | Windows CP1255 | Hebrew | Yes | Yes | 1 | | | `WIN1256` | Windows CP1256 | Arabic | Yes | Yes | 1 | | | `WIN1257` | Windows CP1257 | Baltic | Yes | Yes | 1 | | | `WIN1258` | Windows CP1258 | Vietnamese | Yes | Yes | 1 | `ABC`, `TCVN`, `TCVN5712`, `VSCII` |
Not all client APIs support all the listed character sets. For example, the PostgreSQL JDBC driver does not support `MULE_INTERNAL`, `LATIN6`, `LATIN8`, and `LATIN10`. The `SQL_ASCII` setting behaves considerably differently from the other settings. When the server character set is `SQL_ASCII`, the server interprets byte values 0–127 according to the ASCII standard, while byte values 128–255 are taken as uninterpreted characters. No encoding conversion will be done when the setting is `SQL_ASCII`. Thus, this setting is not so much a declaration that a specific encoding is in use, as a declaration of ignorance about the encoding. In most cases, if you are working with any non-ASCII data, it is unwise to use the `SQL_ASCII` setting because PostgreSQL will be unable to help you by converting or validating non-ASCII characters. ## 23.3.2. Setting the Character Set [#](#MULTIBYTE-SETTING) `initdb` defines the default character set (encoding) for a PostgreSQL cluster. For example, ``` initdb -E EUC_JP ``` sets the default character set to `EUC_JP` (Extended Unix Code for Japanese). You can use `--encoding` instead of `-E` if you prefer longer option strings. If no `-E` or `--encoding` option is given, `initdb` attempts to determine the appropriate encoding to use based on the specified or default locale. You can specify a non-default encoding at database creation time, provided that the encoding is compatible with the selected locale: ``` createdb -E EUC_KR -T template0 --lc-collate=ko_KR.euckr --lc-ctype=ko_KR.euckr korean ``` This will create a database named `korean` that uses the character set `EUC_KR`, and locale `ko_KR`. Another way to accomplish this is to use this SQL command: ``` CREATE DATABASE korean WITH ENCODING 'EUC_KR' LC_COLLATE='ko_KR.euckr' LC_CTYPE='ko_KR.euckr' TEMPLATE=template0; ``` Notice that the above commands specify copying the `template0` database. When copying any other database, the encoding and locale settings cannot be changed from those of the source database, because that might result in corrupt data. For more information see [Section 22.3](/server-administration/managing-databases/manage-ag-templatedbs.md). The encoding for a database is stored in the system catalog `pg_database`. You can see it by using the `psql` `-l` option or the `\l` command. ``` $ psql -l List of databases Name | Owner | Encoding | Collation | Ctype | Access Privileges -----------+----------+-----------+-------------+-------------+------------------------------------- clocaledb | hlinnaka | SQL_ASCII | C | C | englishdb | hlinnaka | UTF8 | en_GB.UTF8 | en_GB.UTF8 | japanese | hlinnaka | UTF8 | ja_JP.UTF8 | ja_JP.UTF8 | korean | hlinnaka | EUC_KR | ko_KR.euckr | ko_KR.euckr | postgres | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 | template0 | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 | {=c/hlinnaka,hlinnaka=CTc/hlinnaka} template1 | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 | {=c/hlinnaka,hlinnaka=CTc/hlinnaka} (7 rows) ``` ## Important On most modern operating systems, PostgreSQL can determine which character set is implied by the `LC_CTYPE` setting, and it will enforce that only the matching database encoding is used. On older systems it is your responsibility to ensure that you use the encoding expected by the locale you have selected. A mistake in this area is likely to lead to strange behavior of locale-dependent operations such as sorting. PostgreSQL will allow superusers to create databases with `SQL_ASCII` encoding even when `LC_CTYPE` is not `C` or `POSIX`. As noted above, `SQL_ASCII` does not enforce that the data stored in the database has any particular encoding, and so this choice poses risks of locale-dependent misbehavior. Using this combination of settings is deprecated and may someday be forbidden altogether. ## 23.3.3. Automatic Character Set Conversion Between Server and Client [#](#MULTIBYTE-AUTOMATIC-CONVERSION) PostgreSQL supports automatic character set conversion between server and client for many combinations of character sets ([Section 23.3.4](#MULTIBYTE-CONVERSIONS-SUPPORTED) shows which ones). To enable automatic character set conversion, you have to tell PostgreSQL the character set (encoding) you would like to use in the client. There are several ways to accomplish this: * Using the `\encoding` command in psql. `\encoding` allows you to change client encoding on the fly. For example, to change the encoding to `SJIS`, type: ``` \encoding SJIS ``` * libpq ([Section 32.11](/client-interfaces/libpq/libpq-control.md)) has functions to control the client encoding. * Using `SET client_encoding TO`. Setting the client encoding can be done with this SQL command: ``` SET CLIENT_ENCODING TO 'value'; ``` Also you can use the standard SQL syntax `SET NAMES` for this purpose: ``` SET NAMES 'value'; ``` To query the current client encoding: ``` SHOW client_encoding; ``` To return to the default encoding: ``` RESET client_encoding; ``` * Using `PGCLIENTENCODING`. If the environment variable `PGCLIENTENCODING` is defined in the client's environment, that client encoding is automatically selected when a connection to the server is made. (This can subsequently be overridden using any of the other methods mentioned above.) * Using the configuration variable [client\_encoding](/server-administration/runtime-config/runtime-config-client.md#GUC-CLIENT-ENCODING). If the `client_encoding` variable is set, that client encoding is automatically selected when a connection to the server is made. (This can subsequently be overridden using any of the other methods mentioned above.) If the conversion of a particular character is not possible — suppose you chose `EUC_JP` for the server and `LATIN1` for the client, and some Japanese characters are returned that do not have a representation in `LATIN1` — an error is reported. If the client character set is defined as `SQL_ASCII`, encoding conversion is disabled, regardless of the server's character set. (However, if the server's character set is not `SQL_ASCII`, the server will still check that incoming data is valid for that encoding; so the net effect is as though the client character set were the same as the server's.) Just as for the server, use of `SQL_ASCII` is unwise unless you are working with all-ASCII data. ## 23.3.4. Available Character Set Conversions [#](#MULTIBYTE-CONVERSIONS-SUPPORTED) PostgreSQL allows conversion between any two character sets for which a conversion function is listed in the [`pg_conversion`](/internals/catalogs/catalog-pg-conversion.md) system catalog. PostgreSQL comes with some predefined conversions, as summarized in [Table 23.4](#MULTIBYTE-TRANSLATION-TABLE) and shown in more detail in [Table 23.5](#BUILTIN-CONVERSIONS-TABLE). You can create a new conversion using the SQL command [CREATE CONVERSION](/reference/sql-commands/sql-createconversion.md). (To be used for automatic client/server conversions, a conversion must be marked as “default” for its character set pair.) **Table 23.4. Built-in Client/Server Character Set Conversions** | Server Character Set | Available Client Character Sets | | -------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- | | `BIG5` | *not supported as a server encoding* | | `EUC_CN` | *EUC\_CN*, `MULE_INTERNAL`, `UTF8` | | `EUC_JP` | *EUC\_JP*, `MULE_INTERNAL`, `SJIS`, `UTF8` | | `EUC_JIS_2004` | *EUC\_JIS\_2004*, `SHIFT_JIS_2004`, `UTF8` | | `EUC_KR` | *EUC\_KR*, `MULE_INTERNAL`, `UTF8` | | `EUC_TW` | *EUC\_TW*, `BIG5`, `MULE_INTERNAL`, `UTF8` | | `GB18030` | *not supported as a server encoding* | | `GBK` | *not supported as a server encoding* | | `ISO_8859_5` | *ISO\_8859\_5*, `KOI8R`, `MULE_INTERNAL`, `UTF8`, `WIN866`, `WIN1251` | | `ISO_8859_6` | *ISO\_8859\_6*, `UTF8` | | `ISO_8859_7` | *ISO\_8859\_7*, `UTF8` | | `ISO_8859_8` | *ISO\_8859\_8*, `UTF8` | | `JOHAB` | *not supported as a server encoding* | | `KOI8R` | *KOI8R*, `ISO_8859_5`, `MULE_INTERNAL`, `UTF8`, `WIN866`, `WIN1251` | | `KOI8U` | *KOI8U*, `UTF8` | | `LATIN1` | *LATIN1*, `MULE_INTERNAL`, `UTF8` | | `LATIN2` | *LATIN2*, `MULE_INTERNAL`, `UTF8`, `WIN1250` | | `LATIN3` | *LATIN3*, `MULE_INTERNAL`, `UTF8` | | `LATIN4` | *LATIN4*, `MULE_INTERNAL`, `UTF8` | | `LATIN5` | *LATIN5*, `UTF8` | | `LATIN6` | *LATIN6*, `UTF8` | | `LATIN7` | *LATIN7*, `UTF8` | | `LATIN8` | *LATIN8*, `UTF8` | | `LATIN9` | *LATIN9*, `UTF8` | | `LATIN10` | *LATIN10*, `UTF8` | | `MULE_INTERNAL` | *MULE\_INTERNAL*, `BIG5`, `EUC_CN`, `EUC_JP`, `EUC_KR`, `EUC_TW`, `ISO_8859_5`, `KOI8R`, `LATIN1` to `LATIN4`, `SJIS`, `WIN866`, `WIN1250`, `WIN1251` | | `SJIS` | *not supported as a server encoding* | | `SHIFT_JIS_2004` | *not supported as a server encoding* | | `SQL_ASCII` | *any (no conversion will be performed)* | | `UHC` | *not supported as a server encoding* | | `UTF8` | *all supported encodings* | | `WIN866` | *WIN866*, `ISO_8859_5`, `KOI8R`, `MULE_INTERNAL`, `UTF8`, `WIN1251` | | `WIN874` | *WIN874*, `UTF8` | | `WIN1250` | *WIN1250*, `LATIN2`, `MULE_INTERNAL`, `UTF8` | | `WIN1251` | *WIN1251*, `ISO_8859_5`, `KOI8R`, `MULE_INTERNAL`, `UTF8`, `WIN866` | | `WIN1252` | *WIN1252*, `UTF8` | | `WIN1253` | *WIN1253*, `UTF8` | | `WIN1254` | *WIN1254*, `UTF8` | | `WIN1255` | *WIN1255*, `UTF8` | | `WIN1256` | *WIN1256*, `UTF8` | | `WIN1257` | *WIN1257*, `UTF8` | | `WIN1258` | *WIN1258*, `UTF8` |
**Table 23.5. All Built-in Character Set Conversions**
Conversion Name [a]Source EncodingDestination Encoding
big5_to_euc_twBIG5EUC_TW
big5_to_micBIG5MULE_INTERNAL
big5_to_utf8BIG5UTF8
euc_cn_to_micEUC_CNMULE_INTERNAL
euc_cn_to_utf8EUC_CNUTF8
euc_jp_to_micEUC_JPMULE_INTERNAL
euc_jp_to_sjisEUC_JPSJIS
euc_jp_to_utf8EUC_JPUTF8
euc_kr_to_micEUC_KRMULE_INTERNAL
euc_kr_to_utf8EUC_KRUTF8
euc_tw_to_big5EUC_TWBIG5
euc_tw_to_micEUC_TWMULE_INTERNAL
euc_tw_to_utf8EUC_TWUTF8
gb18030_to_utf8GB18030UTF8
gbk_to_utf8GBKUTF8
iso_8859_10_to_utf8LATIN6UTF8
iso_8859_13_to_utf8LATIN7UTF8
iso_8859_14_to_utf8LATIN8UTF8
iso_8859_15_to_utf8LATIN9UTF8
iso_8859_16_to_utf8LATIN10UTF8
iso_8859_1_to_micLATIN1MULE_INTERNAL
iso_8859_1_to_utf8LATIN1UTF8
iso_8859_2_to_micLATIN2MULE_INTERNAL
iso_8859_2_to_utf8LATIN2UTF8
iso_8859_2_to_windows_1250LATIN2WIN1250
iso_8859_3_to_micLATIN3MULE_INTERNAL
iso_8859_3_to_utf8LATIN3UTF8
iso_8859_4_to_micLATIN4MULE_INTERNAL
iso_8859_4_to_utf8LATIN4UTF8
iso_8859_5_to_koi8_rISO_8859_5KOI8R
iso_8859_5_to_micISO_8859_5MULE_INTERNAL
iso_8859_5_to_utf8ISO_8859_5UTF8
iso_8859_5_to_windows_1251ISO_8859_5WIN1251
iso_8859_5_to_windows_866ISO_8859_5WIN866
iso_8859_6_to_utf8ISO_8859_6UTF8
iso_8859_7_to_utf8ISO_8859_7UTF8
iso_8859_8_to_utf8ISO_8859_8UTF8
iso_8859_9_to_utf8LATIN5UTF8
johab_to_utf8JOHABUTF8
koi8_r_to_iso_8859_5KOI8RISO_8859_5
koi8_r_to_micKOI8RMULE_INTERNAL
koi8_r_to_utf8KOI8RUTF8
koi8_r_to_windows_1251KOI8RWIN1251
koi8_r_to_windows_866KOI8RWIN866
koi8_u_to_utf8KOI8UUTF8
mic_to_big5MULE_INTERNALBIG5
mic_to_euc_cnMULE_INTERNALEUC_CN
mic_to_euc_jpMULE_INTERNALEUC_JP
mic_to_euc_krMULE_INTERNALEUC_KR
mic_to_euc_twMULE_INTERNALEUC_TW
mic_to_iso_8859_1MULE_INTERNALLATIN1
mic_to_iso_8859_2MULE_INTERNALLATIN2
mic_to_iso_8859_3MULE_INTERNALLATIN3
mic_to_iso_8859_4MULE_INTERNALLATIN4
mic_to_iso_8859_5MULE_INTERNALISO_8859_5
mic_to_koi8_rMULE_INTERNALKOI8R
mic_to_sjisMULE_INTERNALSJIS
mic_to_windows_1250MULE_INTERNALWIN1250
mic_to_windows_1251MULE_INTERNALWIN1251
mic_to_windows_866MULE_INTERNALWIN866
sjis_to_euc_jpSJISEUC_JP
sjis_to_micSJISMULE_INTERNAL
sjis_to_utf8SJISUTF8
windows_1258_to_utf8WIN1258UTF8
uhc_to_utf8UHCUTF8
utf8_to_big5UTF8BIG5
utf8_to_euc_cnUTF8EUC_CN
utf8_to_euc_jpUTF8EUC_JP
utf8_to_euc_krUTF8EUC_KR
utf8_to_euc_twUTF8EUC_TW
utf8_to_gb18030UTF8GB18030
utf8_to_gbkUTF8GBK
utf8_to_iso_8859_1UTF8LATIN1
utf8_to_iso_8859_10UTF8LATIN6
utf8_to_iso_8859_13UTF8LATIN7
utf8_to_iso_8859_14UTF8LATIN8
utf8_to_iso_8859_15UTF8LATIN9
utf8_to_iso_8859_16UTF8LATIN10
utf8_to_iso_8859_2UTF8LATIN2
utf8_to_iso_8859_3UTF8LATIN3
utf8_to_iso_8859_4UTF8LATIN4
utf8_to_iso_8859_5UTF8ISO_8859_5
utf8_to_iso_8859_6UTF8ISO_8859_6
utf8_to_iso_8859_7UTF8ISO_8859_7
utf8_to_iso_8859_8UTF8ISO_8859_8
utf8_to_iso_8859_9UTF8LATIN5
utf8_to_johabUTF8JOHAB
utf8_to_koi8_rUTF8KOI8R
utf8_to_koi8_uUTF8KOI8U
utf8_to_sjisUTF8SJIS
utf8_to_windows_1258UTF8WIN1258
utf8_to_uhcUTF8UHC
utf8_to_windows_1250UTF8WIN1250
utf8_to_windows_1251UTF8WIN1251
utf8_to_windows_1252UTF8WIN1252
utf8_to_windows_1253UTF8WIN1253
utf8_to_windows_1254UTF8WIN1254
utf8_to_windows_1255UTF8WIN1255
utf8_to_windows_1256UTF8WIN1256
utf8_to_windows_1257UTF8WIN1257
utf8_to_windows_866UTF8WIN866
utf8_to_windows_874UTF8WIN874
windows_1250_to_iso_8859_2WIN1250LATIN2
windows_1250_to_micWIN1250MULE_INTERNAL
windows_1250_to_utf8WIN1250UTF8
windows_1251_to_iso_8859_5WIN1251ISO_8859_5
windows_1251_to_koi8_rWIN1251KOI8R
windows_1251_to_micWIN1251MULE_INTERNAL
windows_1251_to_utf8WIN1251UTF8
windows_1251_to_windows_866WIN1251WIN866
windows_1252_to_utf8WIN1252UTF8
windows_1256_to_utf8WIN1256UTF8
windows_866_to_iso_8859_5WIN866ISO_8859_5
windows_866_to_koi8_rWIN866KOI8R
windows_866_to_micWIN866MULE_INTERNAL
windows_866_to_utf8WIN866UTF8
windows_866_to_windows_1251WIN866WIN
windows_874_to_utf8WIN874UTF8
euc_jis_2004_to_utf8EUC_JIS_2004UTF8
utf8_to_euc_jis_2004UTF8EUC_JIS_2004
shift_jis_2004_to_utf8SHIFT_JIS_2004UTF8
utf8_to_shift_jis_2004UTF8SHIFT_JIS_2004
euc_jis_2004_to_shift_jis_2004EUC_JIS_2004SHIFT_JIS_2004
shift_jis_2004_to_euc_jis_2004SHIFT_JIS_2004EUC_JIS_2004
[a] The conversion names follow a standard naming scheme: The official name of the source encoding with all non-alphanumeric characters replaced by underscores, followed by _to_, followed by the similarly processed destination encoding name. Therefore, these names sometimes deviate from the customary encoding names shown in Table 23.3.

## 23.3.5. Further Reading [#](#MULTIBYTE-FURTHER-READING) These are good sources to start learning about various kinds of encoding systems. *CJKV Information Processing: Chinese, Japanese, Korean & Vietnamese Computing* : Contains detailed explanations of `EUC_JP`, `EUC_CN`, `EUC_KR`, `EUC_TW`. : The web site of the Unicode Consortium. [RFC 3629](https://datatracker.ietf.org/doc/html/rfc3629) : UTF-8 (8-bit UCS/Unicode Transformation Format) is defined here. *** 原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/multibyte.html)（英文原文，待翻譯） --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.postgresql.tw/server-administration/charset/multibyte.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.