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DocumentationTencentDB for MySQLKernel FeaturesChecking and Fixing Kernel IssuesCrash Caused by Adding More Than 1024 Columns Using Instant ADD COLUMN

Crash Caused by Adding More Than 1024 Columns Using Instant ADD COLUMN

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Last updated: 2025-12-24 16:09:19

Issue

A crash occurs when more than 1024 columns are added using instant ADD COLUMN.

Issue Triggering Scenarios

MySQL 8.0 20221221 and earlier versions allow instant ADD COLUMN operations even when the row size exceeds half the page size. After a kernel version upgrade, a rollback failure may occur due to row size exceeding the limit during the rollback.

Affected Kernel Versions

MySQL 8.0 20221221 and earlier versions.

Fixed Kernel Version

MySQL 8.0 20241005.

Check Methods

You can refer to the following commands to check for tables with potential risks.
select replace(name, '/', '.') as 'table_schema.table_name' from information_schema.innodb_tables where TOTAL_ROW_VERSIONS!=0 or INSTANT_COLS!=0;

Fixing Methods

1. Upgrade the kernel version to MySQL 8.0 20241005. For the operation method, see Upgrading the Kernel Minor Version.
2. After a kernel version upgrade, rebuild and repair the corrupted tables. You can use the method alter table xx engine = innodb; for repair. To avoid business impact caused by table locking, it is recommended to perform the repair during off-peak hours using tools such as pt-osc.

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