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Performing Instant drop Followed by Instant add Column for a Column with the Same Name Causes a crash
Last updated: 2025-12-08 15:56:17
Performing Instant drop Followed by Instant add Column for a Column with the Same Name Causes a crash
Last updated: 2025-12-08 15:56:17

Problem

Performing Instant drop followed by Instant add column for a column with the same name causes a crash.

Issue-Triggering Scenario

After Instant drop is performed, the actual column is not deleted but is renamed to a hidden column. If Instant add column is then performed to add a column with the same name as the hidden column, it will cause metadata corruption, leading to a crash.

Kernel Version Related to the Issue

TXSQL 8.0 versions prior to 3.1.15.001.

Fixed Kernel Version

TXSQL 8.0 3.1.16.003.

Method for Checking

You can refer to the following command to scan 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;

Method for Fixing

1. Upgrade the kernel version to TXSQL 8.0 3.1.16.003. For the procedure, see Upgrading the kernel minor version.
2. After the kernel version is upgraded, rebuild and repair corrupted tables using alter table xx engine = innodb;. To avoid business impact caused by table locking, it is recommended to perform repairs during off-peak hours using tools such as pt-osc.
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