Error
Error Code:
1688
MySQL Error 1688: Index Comment Too Long
Description
This error indicates that the `COMMENT` attribute provided for an index exceeds MySQL's maximum allowed length. It typically occurs when attempting to create or alter an index with a comment string that is longer than the server's configured limit, preventing the operation from completing.
Error Message
Comment for index '%s' is too long (max = %lu)
Known Causes
3 known causesComment String Exceeds Max Length
The most direct cause is providing a comment string for an index that has more characters (or bytes, depending on encoding) than the maximum length permitted by MySQL.
Multi-byte Character Set Issues
When using multi-byte character sets (e.g., UTF-8), the byte length of a comment can exceed the limit even if the character count appears reasonable, as each character may consume more than one byte.
Overly Descriptive Comments
Attempting to include extensive descriptions, full sentences, or documentation snippets directly within the index comment field, without realizing the strict length constraints.
Solutions
Coming SoonDetailed step-by-step solutions for this error are being prepared. In the meantime, try these general troubleshooting tips:
General Troubleshooting Tips
- Check the error message carefully for specific details
- Review recent changes that might have caused the error
- Search for the exact error code in the official documentation
- Check log files for additional context
- Try restarting the application or service