EC
3135
MariaDBERRORNotableDDLHIGH confidence

ALTER TABLE not supported: adding NOT NULL requires table copy

Production Risk

Medium — may fail mid-rebuild if NULLs are encountered; always pre-clean data.

What this means

Adding a NOT NULL constraint to an existing column that may contain NULL values cannot be done in-place and requires a full table copy so that existing NULLs can be replaced or rejected.

Why it happens
  1. 1ALTER TABLE ... MODIFY COLUMN col NOT NULL with ALGORITHM=INPLACE when NULLs may exist.
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE t1 MODIFY COLUMN name VARCHAR(100) NOT NULL, ALGORITHM=INPLACE;

expected output

ERROR 3135 (HY000): ALGORITHM=INPLACE is not supported. Reason: NOT NULL requires table copy.

Fix

Update NULLs first, then use COPY algorithm

Update NULLs first, then use COPY algorithm
UPDATE t1 SET name = '' WHERE name IS NULL;
ALTER TABLE t1 MODIFY COLUMN name VARCHAR(100) NOT NULL, ALGORITHM=COPY;

Why this works

Eliminates NULLs before enforcing the constraint.

What not to do

✕

Sources
Official documentation ↗

MySQL 8.0 — 3135 ER_ALTER_OPERATION_NOT_SUPPORTED_REASON_NOT_NULL2

Content generated with AI assistance and reviewed for accuracy. Found an error? hello@errcodes.dev

← All MariaDB errors