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
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.