EC
3122
MySQLERRORNotableDDLHIGH confidence

ALTER TABLE not supported because table is partitioned

Production Risk

Medium — partition rebuild can be time-consuming for large partitioned tables.

What this means

The requested ALTER TABLE algorithm (INPLACE or INSTANT) cannot be used because the table is partitioned and the operation requires a full table copy.

Why it happens
  1. 1Attempting ALGORITHM=INPLACE on a partitioned InnoDB table where the operation is unsupported.
  2. 2Partition-related changes incompatible with in-place modification.
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE partitioned_t ADD COLUMN y INT, ALGORITHM=INPLACE;

expected output

ERROR 3122 (HY000): ALGORITHM=INPLACE is not supported. Reason: Partition requires table copy.

Fix

Use ALGORITHM=COPY for partitioned tables

Use ALGORITHM=COPY for partitioned tables
ALTER TABLE partitioned_t ADD COLUMN y INT, ALGORITHM=COPY;

Why this works

Rebuilds each partition as needed.

What not to do

✕

Sources
Official documentation ↗

MySQL 8.0 — 3122 ER_ALTER_OPERATION_NOT_SUPPORTED_REASON_PARTITION2

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