Help Center/ GaussDB/ MySQL Compatibility(Distributed)/ MYSQL-compatible Mode/ Collation Rules
Updated on 2025-06-30 GMT+08:00
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Collation Rules

GaussDB allows you to specify the following collation rules for schemas, tables, or columns.

Differences in collation rules:

  • Currently, only the character string type and some binary types support the specified collation rules. You can check whether the typcollation attribute of a type in the pg_type system catalog is not 0 to determine whether the type supports the collation. The collation can be specified for all types in MySQL. However, collation rules are meaningless except those for character strings and binary types.
  • The current collation rules can be specified only when the corresponding character set is the same as the database-level character set.
  • The default collation of the utf8mb4 character set is utf8mb4_general_ci, which is the same as that in MySQL 5.7. utf8mb4_0900_ai_ci is not the default collation of utf8mb4.
  • In GaussDB, utf8 and utf8mb4 are the same character set.
Table 1 Collation rules

MySQL

GaussDB

utf8mb4_general_ci

Supported.

utf8mb4_unicode_ci

Supported.

utf8mb4_bin

Supported.

gbk_chinese_ci

Supported.

gbk_bin

Supported.

gb18030_chinese_ci

Supported.

gb18030_bin

Supported.

binary

Supported.

utf8mb4_0900_ai_ci

Supported.

utf8_general_ci

Supported.

utf8_bin

Supported.
Parent topic: MYSQL-compatible Mode