Online DDL in TDSQL Boundless
Last updated:2026-02-10 11:05:59
This document outlines support for Online DDL (Data Definition Language) operations in TDSQL Boundless. Most common DDL operations are supported online, including many inplace operations that only require metadata changes.
Support for Online DDL
Secondary Index Operations
Operation | Syntax Supported | Online Change | Reason for Not Supporting Online Change | Metadata-Only | Data Operation | Permits Concurrent DML |
Creating/Adding a secondary index | Yes | Yes | / | No | Requires data backfill | Yes |
Dropping an index | Yes | Yes | / | No | Requires asynchronous data deletion | Yes |
Renaming an index | Yes | Yes | / | No | / | Yes |
Adding a FULLTEXT index | No | No | Not support this operation | / | / | / |
Adding a SPATIAL index | No | No | Not support this operation | / | / | / |
Changing the index type | No | No | Reason for no support: The engine only supports the default index type, not B-tree, Hash, etc. | / | / | / |
Primary Key Operations
DDL operations that modify a primary key are not supported in online mode. They require locking the table and performing a full copy.
Operation | Syntax Supported | Online Change | Reason for Not Supporting Online Change | Metadata-Only | Data Operation | Permits Concurrent DML |
Adding a primary key | Yes | No | Data reorganization is required. | No | Requires table lock and copy | No |
Dropping a primary key | Yes | No | Data reorganization is required. | No | Requires table lock and copy | No |
Dropping a primary key and adding another | Yes | Yes | / | No | Requires table lock and copy | Yes |
Column Operations
Operatio | Syntax Supported | Online Change | Reason for Not Supporting Online Change | Metadata-Only | Data Operation | Permits Concurrent DML |
Adding a column (at the end) | Yes | Yes | / | Yes | Yes | |
Adding a column (not at the end) | Yes | Yes | / | No | Requires Online Copy | Yes |
Dropping a column | Yes | Yes | / | No | Requires Online Copy | Yes |
Renaming a column | Yes | Yes | / | Yes | / | Yes |
Reordering columns | Yes | Yes | / | No | Requires Online Copy | Yes |
Setting a column default value | Yes | Yes | / | Yes | / | Yes |
Changing a column data type | Yes | Yes | / | No | Requires Online Copy | Yes |
Extending VARCHAR column size (not in PK) | Yes | Yes | / | Varies* | Varies* | Yes |
Extending VARCHAR column size (in PK) | Yes | Yes | / | No | Requires Online Copy | Yes |
Dropping a column default value | Yes | Yes | / | Yes | / | Yes |
Changing the auto-increment value | Yes | Yes | / | Yes | / | Yes |
Making a column NULL | Yes | Yes | / | No | Requires Online Copy | Yes |
Making a column NOT NULL | Yes | Yes | / | No | Requires Online Copy | Yes |
Modifying ENUM or SET Definition | Yes | Yes | / | Yes | / | Yes |
Table Operations
Operation | Syntax Supported | Online Change | Reason for Not Supporting Online Change | Metadata-Only | Data Operation | Permits Concurrent DML |
Changing the ROW_FORMAT | No | No | Not support this operation | / | / | / |
Changing the KEY_BLOCK_SIZE | No | No | Not support this operation | / | / | / |
Setting persistent table statistics | No | No | Not support this operation | / | / | / |
Specifying a character set | Yes | Yes | / | No | Requires Online Copy | Yes |
Converting a character set | Yes | Yes | / | No | Requires Online Copy | Yes |
Optimizing a table | Yes | / | This command returns success immediately but performs no action, as the engine's automatic compaction makes it unnecessary | / | / | / |
Rebuilding with the FORCE option | Yes | Yes | / | No | Requires Online Copy | Yes |
Performing a null rebuild | No | No | Not support this operation | / | / | / |
Renaming a table | Yes | Yes | / | Yes | / | Yes |
Partitioning Operations
Operation | Syntax Supported | Online Change | Reason for Not Supporting Online Change | Metadata-Only | Data Operation | Permits Concurrent DML |
PARTITION BY | Yes | Yes | / | No | Requires Online Copy | Yes |
ADD PARTITION | Yes | Yes | / | Yes | / | Yes |
DROP PARTITION | Yes | Yes | / | Yes | / | Yes |
DISCARD PARTITION | No | No | Not support this operation | / | / | / |
IMPORT PARTITION | No | No | Not support this operation | / | / | / |
TRUNCATE PARTITION | Yes | Yes | / | / | Async data deletion | Yes |
COALESCE PARTITION | Yes | Yes | / | No | Requires Online Copy | Yes |
REORGANIZE PARTITION | Yes | Yes | / | No | Requires Online Copy | Yes |
EXCHANGE PARTITION | No | No | Not support this operation | / | / | / |
ANALYZE PARTITION | No | No | Not support this operation | / | / | / |
CHECK PARTITION | No | No | Not support this operation | / | / | / |
OPTIMIZE PARTITION | Yes | / | This command returns success immediately but performs no action, as the engine's automatic compaction makes it unnecessary | / | / | / |
REBUILD PARTITION | Yes | Yes | / | No | Requires Online Copy | Yes |
REPAIR PARTITION | Yes | No | Not counted as DDL | / | / | / |
REMOVE PARTITIONING | Yes | Yes | / | No | Requires Online Copy | Yes |
Tablespace Operations
Tablespaces operations are not supported.
Generated Column Operations
Generated Column operations are not supported.
Foreign Key Operations
Foreign Key operations are not supported.
Comparison with Community MySQL 8.0
Both the Inplace and Online Copy operations of TDSQL Boundless and the Instant and Inplace operations of Community Edition MySQL 8.0 are considered Online operations. Their differences for common DDL operations are compared as follows.
Operation | TDSQL Boundless | MySQL |
Converting a character set | Allows concurrent DML | Blocks concurrent DML |
Changing the column data type | Allows concurrent DML | Blocks concurrent DML |
PARTITION BY | Allows concurrent DML | Blocks concurrent DML |
Extending VARCHAR column size | Allows concurrent DML | Support is conditional, with limits on X in VARCHAR(X). |
Adding a primary key | Blocks concurrent DML | Allows concurrent DML |
Note:
TDSQL Boundless currently does not yet support a small number of DDL operations. Therefore, this section only explains the differences between TDSQL Boundless and the community edition MySQL 8.0 regarding their commonly supported features.
For the type for extending the size of VARCHAR columns, the community edition MySQL 8.0 limits the character length specified by VARCHAR(X), mainly involving the pack length for storage. Assuming that UTF8MB4 is used as the character set, the number of bytes occupied by a field is X*4.
If the old size (X * 4) and new size (Y * 4) are both less than 256 bytes, the operation is INPLACE;
If the old size is less than 256 but the new size is greater than or equal to 256 bytes, the operation is not INPLACE.
Example:
CREATETABLEt1(aINTPRIMARYKEY,bVARCHAR(10))ENGINE=InnoDBDEFAULTCHARSET=utf8mb4COLLATE=utf8mb4_0900_ai_ci;ALTERTABLEt1 CHANGECOLUMNb bVARCHAR(20),ALGORITHM=INPLACE,LOCK=NONE;→ Succeeded.ALTERTABLEt1 CHANGECOLUMNb bVARCHAR(64),ALGORITHM=INPLACE,LOCK=NONE;→ Failed.
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