Updated on 2025-09-09 GMT+08:00

Collation Rules

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

Differences in collation rules:

  • Currently, collation rules can only be specified for the character string type and some binary types. You can check the typcollation attribute of a type in the pg_type system catalog. If it is not 0, 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 (except binary) can be specified only when the corresponding character set is the same as the database-level character set. In GaussDB, the character set must be the same as the database character set, and multiple character sets cannot be used together in a table.
  • The default collation of the utf8mb4 character set is utf8mb4_general_ci, which is the same as that in MySQL 5.7.
  • 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.