Collations

The default collation of OceanBase Database is utf8mb4_general_ci.

The following table describes the collations supported by OceanBase Database.

Note

• For any Unicode character set, the operation is executed faster if the character set is sorted by a general collation xxx_general_ci instead of a Unicode collation xxx_unicode_ci.
• You cannot modify the collations.

By default, you can execute the SHOW COLLATION statement to display all available collations.

obclient> SHOW COLLATION;
+--------------------+---------+-----+---------+----------+---------+
 Collation           Charset  Id   Default  Compiled  Sortlen 
+--------------------+---------+-----+---------+----------+---------+
 utf8mb4_general_ci  utf8mb4   45  Yes      Yes             1 
 utf8mb4_bin         utf8mb4   46           Yes             1 
 binary              binary    63  Yes      Yes             1 
 gbk_chinese_ci      gbk       28  Yes      Yes             1 
 gbk_bin             gbk       87           Yes             1 
 utf16_general_ci    utf16     54  Yes      Yes             1 
 utf16_bin           utf16     55           Yes             1 
 utf8mb4_unicode_ci  utf8mb4  224           Yes             1 
 utf16_unicode_ci    utf16    101           Yes             1 
 gb18030_chinese_ci  gb18030  248  Yes      Yes             1 
 gb18030_bin         gb18030  249           Yes             1 
+--------------------+---------+-----+---------+----------+---------+
11 rows in set (0.03 sec)

General characteristics of collations:

• Two different character sets cannot use the same collation.

• Each character set uses a default collation. You can execute the SHOW CHARACTER SET statement to indicate the default collation of each character set. The execution result of the SHOW COLLATION statement has a column that indicates whether a collation is the default collation of its character set. If yes, the value is Yes. Otherwise, the value is empty.

• The name of a collation starts with the name of the corresponding character set. In most cases, the name is followed by one or more suffix items that indicate other characteristics of the collation.