3620
MySQLERRORNotableDDLHIGH confidence
Online ALTER not supported for virtual column change
Production Risk
Medium — ALTER fails; a table copy may be required with associated locking impact.
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE t MODIFY COLUMN vc INT GENERATED ALWAYS AS (a + 2) VIRTUAL, ALGORITHM=INPLACE;
expected output
ERROR 3620 (HY000): ALGORITHM=INPLACE is not supported for this change; try ALGORITHM=COPY.
Fix
Use ALGORITHM=COPY
Use ALGORITHM=COPY
ALTER TABLE t MODIFY COLUMN vc INT GENERATED ALWAYS AS (a + 2) VIRTUAL, ALGORITHM=COPY;
Why this works
Forces a full table copy to apply the virtual column change.
What not to do
✕
Version notes
Sources
Official documentation ↗
MySQL 8.0 — 3620 ER_UNSUPPORTED_ALTER_ONLINE_ON_VIRTUAL_COLUMN
Content generated with AI assistance and reviewed for accuracy. Found an error? hello@errcodes.dev