Help Center/ GaussDB/ Service Overview/ Compatibility with MySQL Databases/ Centralized Instances/ MySQL Compatibility in B-Compatible Mode/ Collation Rules
Updated on 2024-05-14 GMT+08:00
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Collation Rules

GaussDB allows you to specify the following collation rules for databases, 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 (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

No.

MySQL

GaussDB

1

utf8mb4_general_ci

Supported.

2

utf8mb4_unicode_ci

Supported.

3

utf8mb4_bin

Supported.

4

gbk_chinese_ci

Supported.

5

gbk_bin

Supported.

6

gb18030_chinese_ci

Supported.

7

gb18030_bin

Supported.

8

binary

Supported.

9

utf8mb4_0900_ai_ci

Supported.

10

utf8_general_ci

Supported.

11

utf8_bin

Supported.