This topic describes the supported conversion scope of CREATE TABLE DDL operations for creating indexes or constraints during data migration from a MySQL database to a MySQL-compatible tenant of OceanBase Database.
Syntax
create_definition: {
col_name column_definition
| {INDEX | KEY} [index_name] [index_type] (key_part,...)
[index_option] ...
| {FULLTEXT | SPATIAL} [INDEX | KEY] [index_name] (key_part,...)
[index_option] ...
| [CONSTRAINT [symbol]] PRIMARY KEY
[index_type] (key_part,...)
[index_option] ...
| [CONSTRAINT [symbol]] UNIQUE [INDEX | KEY]
[index_name] [index_type] (key_part,...)
[index_option] ...
| [CONSTRAINT [symbol]] FOREIGN KEY
[index_name] (col_name,...)
reference_definition
| check_constraint_definition
}
key_part: {col_name [(length)] | (expr)} [ASC | DESC]
index_type:
USING {BTREE | HASH}
index_option: {
KEY_BLOCK_SIZE [=] value
| index_type
| WITH PARSER parser_name
| COMMENT 'string'
| {VISIBLE | INVISIBLE}
|ENGINE_ATTRIBUTE [=] 'string'
|SECONDARY_ENGINE_ATTRIBUTE [=] 'string'
}
check_constraint_definition:
[CONSTRAINT [symbol]] CHECK (expr) [[NOT] ENFORCED]
reference_definition:
REFERENCES tbl_name (key_part,...)
[MATCH FULL | MATCH PARTIAL | MATCH SIMPLE]
[ON DELETE reference_option]
[ON UPDATE reference_option]
reference_option:
RESTRICT | CASCADE | SET NULL | NO ACTION | SET DEFAULT
Supported operations
Create primary keys.
Create unique keys.
Create indexes or keys.
Create foreign keys.
Create foreign keys on fields, functions, or expressions. Specify the ON [DELETE | UPDATE] RESTRICT | CASCADE | NO ACTION | SET DEFAULT attribute.
Create full-text indexes.
Create CHECK constraints in MySQL-compatible tenants of OceanBase Database V3.2.3 and later.
Create prefixed indexes.
Specify the ASC or DESC keyword.
Unsupported operations
Warning
If a DDL statement to be synchronized contains the following unsupported definitions, the conversion will fail and the output will be an empty string.
Create the following types of indexes with functional key parts: PRIMARY KEY, UNIQUE KEY, INDEX/KEY, and FULLTEXT INDEX. (You can create these indexes only on fields.)
Primary key, unique key, index, key, or full-text index definitions that contain functions or expressions. Examples:
CREATE TABLE functional_index_t1 (col1 INT, PRIMARY KEY (col1, (ABS(col1)))); CREATE TABLE functional_index_t1(x VARCHAR(30), INDEX idx ((CAST(x->>'$.name' AS CHAR(30)))));Create spatial indexes.
Specify the ON [DELETE | UPDATE] SET NULL attribute for foreign keys.
Ignored clauses and options
Note
The following clauses and options will be ignored and will not be resolved or converted when they are specified in the synchronized DDL statements.
USING BTREE or USING HASH
KEY_BLOCK_SIZE, index_type, WITH PARSER, COMMENT, VISIBLE | INVISIBLE, ENGINE_ATTRIBUTE, or SECONDARY_ENGINE_ATTRIBUTE in index_option
[NOT] ENFORCED for CHECK constraints
MATCH FULL | MATCH PARTIAL | MATCH SIMPLE for foreign keys
Limitations
Notice
Due to the limitations of MySQL-compatible tenants of OceanBase Database, an error may be returned when the synchronized DDL statements are converted and executed in a MySQL-compatible tenant of OceanBase Database in the following scenarios.
MySQL-compatible tenants of OceanBase Database cannot create the following types of constraints on specific types of fields: PRIMARY KEY, UNIQUE KEY, INDEX/KEY, FULLTEXT INDEX, and FOREIGN KEY.
MySQL-compatible tenants of OceanBase Database do not support specifying certain functions or expressions in CHECK constraints.
MySQL-compatible tenants of OceanBase Database do not support specifying certain functions or expressions in FOREIGN KEY constraints.