<p>MySQL throws Error 1629 when a column comment exceeds the permitted length (1024 bytes).</p>
<p>MySQL Error 1629: ER_TOO_LONG_FIELD_COMMENT occurs when a column comment is larger than the allowed 1024-byte limit. Reduce the comment length with ALTER TABLE ... MODIFY COLUMN ... COMMENT or shorten it during table creation to resolve the issue quickly.</p>
Comment for field '%s' is too long (max = %lu)
Error 1629 (SQLSTATE HY000) appears when a CREATE TABLE or ALTER TABLE statement sets a column comment longer than the server limit of 1024 bytes. MySQL stops the DDL and returns the message “Comment for field '%s' is too long (max = 1024)”.
The problem always involves the length of the COMMENT clause, not the column data size. Fixing it is essential because the operation fails, leaving the schema unchanged.
The primary cause is supplying a COMMENT string that exceeds 1024 bytes after character-set encoding is applied. Using multibyte UTF-8 characters reduces the effective character count, triggering the error sooner.
Generated DDL from ORMs, migration tools, or AI assistants can unknowingly insert verbose comments that break the limit. Copy-pasting large documentation blocks into COMMENT also triggers the exception.
Shorten the COMMENT to 1024 bytes or less, then rerun your DDL. In most cases you can keep the meaningful description by removing redundant text or moving details to external documentation.
When updating an existing table, use ALTER TABLE ... MODIFY COLUMN with a trimmed COMMENT. When creating new tables, review COMMENT lengths before executing migrations.
During CI/CD migrations, a lengthy auto-generated comment causes pipeline failure. Trim the template or set a shorter default comment string.
When using an ORM like Sequelize or Doctrine, inspect the generated SQL. Override the column comment metadata or use annotations to stay within limits.
Adopt a 256-character internal guideline for comments. Validate comment length in code review or CI. Store extensive documentation in README files or a data catalog.
Galaxy’s SQL editor highlights DDL errors inline and flags oversized COMMENT clauses before execution, preventing this issue from reaching production.
The literal string in the COMMENT clause is longer than MySQL allows.
UTF-8 or UTF-16 characters inflate byte size, quickly passing the limit.
ORMs or code generators add verbose comments without checking length.
Developers paste large markdown or HTML into the COMMENT clause.
Raised when the combined column definitions exceed the maximum row size.
Occurs when a single VARCHAR or VARBINARY length surpasses the limit.
A generic syntax error that can surface if the COMMENT clause is malformed.
Raised when index key parts exceed the allowed byte length.
The limit is 1024 bytes after character encoding is applied, not 1024 characters.
The 1024-byte column comment limit has remained constant from MySQL 5.1 through 8.1.
No server variable allows changing the hardcoded 1024-byte limit for column comments.
Galaxy highlights COMMENT clauses that exceed 1024 bytes as you type and offers AI suggestions to shorten them before execution.
.avif)
.avif){kind=logo}
