1783
MariaDBERRORNotableDDLHIGH confidence
INPLACE ALTER not supported due to column type change
Production Risk
Medium — DDL blocked; COPY requires a table lock.
What this means
The ALTER TABLE operation changes a column's data type in a way that is incompatible with in-place execution.
Why it happens
- 1Changing a column from INT to BIGINT, or VARCHAR length changes beyond in-place limits.
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE tbl ALGORITHM=INPLACE, MODIFY COLUMN description TEXT; -- was VARCHAR(255)
expected output
ERROR 1783 (0A000): ALGORITHM=INPLACE is not supported. Reason: Column type incompatible with INPLACE.
Fix
Use ALGORITHM=COPY for incompatible type changes
Use ALGORITHM=COPY for incompatible type changes
ALTER TABLE tbl ALGORITHM=COPY, MODIFY COLUMN description TEXT;
Why this works
Forces a full table rebuild that accommodates any column type change.
What not to do
✕
Sources
Official documentation ↗
MySQL 8.0 — 1783 ER_ALTER_OPERATION_NOT_SUPPORTED_REASON_COLUMN_TYPE
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