1637
MySQLERRORCriticalSchemaHIGH confidence
Index comment is too long
Production Risk
Low — DDL statement is rejected; table remains unchanged.
What this means
The COMMENT clause on an index definition exceeds the maximum allowed length (1024 bytes).
Why it happens
- 1The index COMMENT string is longer than 1024 bytes.
How to reproduce
trigger — this will error
trigger — this will error
-- Index comment exceeding 1024 bytes
expected output
ERROR 1637 (HY000): Comment for index 'idx' is too long (max = 1024).
Fix
Shorten the index comment
Shorten the index comment
CREATE TABLE t (id INT, INDEX idx (id) COMMENT 'Short comment');
Why this works
Keeping the comment within 1024 bytes satisfies the length constraint.
Sources
Official documentation ↗
MySQL 8.0 — 1637 ER_TOO_LONG_INDEX_COMMENT
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