Character Set Support

The character set support in Greenplum Database allows you to store text in a variety of character sets, 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 Greenplum Database array using gpinitsystem. It can be overridden when you create a database, so you can have multiple databases each with a different character set.

Table 1. Greenplum Database Character Sets 1
NameDescriptionLanguageServer?Bytes/CharAliases
BIG5Big FiveTraditional ChineseNo1-2WIN950, Windows950
EUC_CNExtended UNIX Code-CNSimplified ChineseYes1-3 
EUC_JPExtended UNIX Code-JPJapaneseYes1-3 
EUC_KRExtended UNIX Code-KRKoreanYes1-3 
EUC_TWExtended UNIX Code-TWTraditional Chinese, TaiwaneseYes1-3 
GB18030National StandardChineseNo1-2 
GBKExtended National StandardSimplified ChineseNo1-2WIN936, Windows936
ISO_8859_5ISO 8859-5, ECMA 113Latin/CyrillicYes1 
ISO_8859_6ISO 8859-6, ECMA 114Latin/ArabicYes1 
ISO_8859_7ISO 8859-7, ECMA 118Latin/GreekYes1 
ISO_8859_8ISO 8859-8, ECMA 121Latin/HebrewYes1 
JOHABJOHAKorean (Hangul)Yes1-3 
KOI8KOI8-R(U)CyrillicYes1KOI8R
LATIN1ISO 8859-1, ECMA 94Western EuropeanYes1ISO88591
LATIN2ISO 8859-2, ECMA 94Central EuropeanYes1ISO88592
LATIN3ISO 8859-3, ECMA 94South EuropeanYes1ISO88593
LATIN4ISO 8859-4, ECMA 94North EuropeanYes1ISO88594
LATIN5ISO 8859-9, ECMA 128TurkishYes1ISO88599
LATIN6ISO 8859-10, ECMA 144NordicYes1ISO885910
LATIN7ISO 8859-13BalticYes1ISO885913
LATIN8ISO 8859-14CelticYes1ISO885914
LATIN9ISO 8859-15LATIN1 with Euro and accentsYes1ISO885915
LATIN10ISO 8859-16, ASRO SR 14111RomanianYes1ISO885916
MULE_INTERNALMule internal codeMultilingual EmacsYes1-4 
SJISShift JISJapaneseNo1-2Mskanji, ShiftJIS, WIN932, Windows932
SQL_ASCIIunspecified 2anyNo1 
UHCUnified Hangul CodeKoreanNo1-2WIN949, Windows949
UTF8Unicode, 8-bitallYes1-4Unicode
WIN866Windows CP866CyrillicYes1ALT
WIN874Windows CP874ThaiYes1 
WIN1250Windows CP1250Central EuropeanYes1 
WIN1251Windows CP1251CyrillicYes1WIN
WIN1252Windows CP1252Western EuropeanYes1 
WIN1253Windows CP1253GreekYes1 
WIN1254Windows CP1254TurkishYes1 
WIN1255Windows CP1255HebrewYes1 
WIN1256Windows CP1256ArabicYes1 
WIN1257Windows CP1257BalticYes1 
WIN1258Windows CP1258VietnameseYes1ABC, TCVN, TCVN5712, VSCII

Parent topic: Greenplum Database Reference Guide

Setting the Character Set

gpinitsystem defines the default character set for a Greenplum Database system by reading the setting of the ENCODING parameter in the gp_init_config file at initialization time. The default character set is UNICODE or UTF8.

You can create a database with a different character set besides what is used as the system-wide default. For example:

  1. => CREATE DATABASE korean WITH ENCODING 'EUC_KR';

Important: Although you can specify any encoding you want for a database, it is unwise to choose an encoding that is not what is expected by the locale you have selected. The LC_COLLATE and LC_CTYPE settings imply a particular encoding, and locale-dependent operations (such as sorting) are likely to misinterpret data that is in an incompatible encoding.

Since these locale settings are frozen by gpinitsystem, the apparent flexibility to use different encodings in different databases is more theoretical than real.

One way to use multiple encodings safely is to set the locale to C or POSIX during initialization time, thus disabling any real locale awareness.

Character Set Conversion Between Server and Client

Greenplum Database supports automatic character set conversion between server and client for certain character set combinations. The conversion information is stored in the master pg_conversion system catalog table. Greenplum Database comes with some predefined conversions or you can create a new conversion using the SQL command CREATE CONVERSION.

Table 2. Client/Server Character Set Conversions
Server Character SetAvailable Client Character Sets
BIG5not supported as a server encoding
EUC_CNEUC_CN, MULE_INTERNAL, UTF8
EUC_JPEUC_JP, MULE_INTERNAL, SJIS, UTF8
EUC_KREUC_KR, MULE_INTERNAL, UTF8
EUC_TWEUC_TW, BIG5, MULE_INTERNAL, UTF8
GB18030not supported as a server encoding
GBKnot supported as a server encoding
ISO_8859_5ISO_8859_5, KOI8, MULE_INTERNAL, UTF8, WIN866, WIN1251
ISO_8859_6ISO_8859_6, UTF8
ISO_8859_7ISO_8859_7, UTF8
ISO_8859_8ISO_8859_8, UTF8
JOHABJOHAB, UTF8
KOI8KOI8, ISO_8859_5, MULE_INTERNAL, UTF8, WIN866, WIN1251
LATIN1LATIN1, MULE_INTERNAL, UTF8
LATIN2LATIN2, MULE_INTERNAL, UTF8, WIN1250
LATIN3LATIN3, MULE_INTERNAL, UTF8
LATIN4LATIN4, MULE_INTERNAL, UTF8
LATIN5LATIN5, UTF8
LATIN6LATIN6, UTF8
LATIN7LATIN7, UTF8
LATIN8LATIN8, UTF8
LATIN9LATIN9, UTF8
LATIN10LATIN10, UTF8
MULE_INTERNALMULE_INTERNAL, BIG5, EUC_CN, EUC_JP, EUC_KR, EUC_TW, ISO_8859_5, KOI8, LATIN1 to LATIN4, SJIS, WIN866, WIN1250, WIN1251
SJISnot supported as a server encoding
SQL_ASCIInot supported as a server encoding
UHCnot supported as a server encoding
UTF8all supported encodings
WIN866WIN866
ISO_8859_5KOI8, MULE_INTERNAL, UTF8, WIN1251
WIN874WIN874, UTF8
WIN1250WIN1250, LATIN2, MULE_INTERNAL, UTF8
WIN1251WIN1251, ISO_8859_5, KOI8, MULE_INTERNAL, UTF8, WIN866
WIN1252WIN1252, UTF8
WIN1253WIN1253, UTF8
WIN1254WIN1254, UTF8
WIN1255WIN1255, UTF8
WIN1256WIN1256, UTF8
WIN1257WIN1257, UTF8
WIN1258WIN1258, UTF8

To enable automatic character set conversion, you have to tell Greenplum Database 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, which allows you to change client encoding on the fly.

  • Using SETclient_encoding TO.

    To set the client encoding, use the following SQL command:

    1. => SET CLIENT_ENCODING TO 'value';

    To query the current client encoding:

    1. => SHOW client_encoding;

    To return to the default encoding:

    1. => RESET client_encoding;

  • Using the PGCLIENTENCODING environment variable. When 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.)

  • Setting the configuration parameter client_encoding. If client_encoding is set in the master postgresql.conf file, that client encoding is automatically selected when a connection to Greenplum Database 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, then some Japanese characters do not have a representation in LATIN1 “ then 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. The use of SQL_ASCII is unwise unless you are working with all-ASCII data. SQL_ASCII is not supported as a server encoding.

1 Not all APIs support all the listed character sets. For example, the JDBC driver does not support MULE_INTERNAL, LATIN6, LATIN8, and LATIN10.

2 The SQL_ASCII setting behaves considerably differently from the other settings. Byte values 0-127 are interpreted according to the ASCII standard, while byte values 128-255 are taken as uninterpreted characters. If you are working with any non-ASCII data, it is unwise to use the SQL_ASCII setting as a client encoding. SQL_ASCII is not supported as a server encoding.

Need help? Visit the Greenplum Database Community