1788
MySQLERRORNotableDDLHIGH confidence
INPLACE ALTER not supported — hidden FTS document ID column
Production Risk
Low — DDL rejected.
What this means
The ALTER TABLE operation requires COPY algorithm because the table has a hidden FULLTEXT search document ID column (FTS_DOC_ID) that cannot be maintained in-place.
Why it happens
- 1Modifying a table that has a FULLTEXT index (and the hidden FTS_DOC_ID column) using ALGORITHM=INPLACE.
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE articles ALGORITHM=INPLACE, ADD COLUMN author VARCHAR(100); -- articles has FULLTEXT
expected output
ERROR 1788 (0A000): ALGORITHM=INPLACE is not supported. Reason: Fulltext index creation requires COPY.
Fix
Use ALGORITHM=COPY for tables with FULLTEXT indexes
Use ALGORITHM=COPY for tables with FULLTEXT indexes
ALTER TABLE articles ALGORITHM=COPY, ADD COLUMN author VARCHAR(100);
Why this works
COPY algorithm rebuilds the FTS index and hidden document ID column correctly.
What not to do
✕
Sources
Official documentation ↗
MySQL 8.0 — 1788 ER_ALTER_OPERATION_NOT_SUPPORTED_REASON_HIDDEN_FTS
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