Bug #112153 ADD COLUMN with expressional DEFAULT does not support online ALTER TABLE

• Submitted: 23 Aug 2023 7:30
• Modified: 23 Aug 2023 7:51
• Reporter: Tsubasa Tanaka (OCA)
• Status: Verified
• Category: MySQL Server: Documentation
• Severity: S3 (Non-critical)
• Version: 8.0.34,8.1.0
• OS: Any
• CPU Architecture: Any

[23 Aug 2023 7:30] Tsubasa Tanaka

Description:
This is documentation issue.

ADD COLUMN with expressional DEFAULT does not support online ALTER TABLE.
But the documentation doesn't describe it.

https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl-operations.html
https://dev.mysql.com/doc/refman/8.1/en/innodb-online-ddl-operations.html

How to repeat:
CREATE TABLE t1 (num serial, val varchar(32));

mysql81 54> ALTER TABLE t1 ADD c varchar(32) DEFAULT ('{}'), ALGORITHM= INSTANT;
ERROR 1845 (0A000): ALGORITHM=INSTANT is not supported for this operation. Try ALGORITHM=COPY/INPLACE.

mysql81 54> ALTER TABLE t1 ADD c varchar(32) DEFAULT ('{}'), ALGORITHM= INPLACE;
ERROR 1845 (0A000): ALGORITHM=INPLACE is not supported for this operation. Try ALGORITHM=COPY.

Suggested fix:
Add description of this limitation into the document.

https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl-operations.html
https://dev.mysql.com/doc/refman/8.1/en/innodb-online-ddl-operations.html

[23 Aug 2023 7:51] MySQL Verification Team

Hello tanaka-San,

Thank you for the report and feedback.

regards,
Umesh