Error
Error Code:
1089
MySQL Error 1089: Incorrect Prefix Key Definition
Description
This error indicates an issue when defining an index with a column prefix. It typically occurs during `CREATE TABLE` or `ALTER TABLE` statements when the specified prefix for a key is invalid, either due to the column's data type, the prefix length, or storage engine limitations.
Error Message
Incorrect prefix key; the used key part isn't a string, the used length is longer than the key part, or the storage engine doesn't support unique prefix keys
Known Causes
3 known causesPrefix on Non-String Column
Attempting to define a prefix key on a column that is not a string type (e.g., INT, DATE, BLOB without explicit length), which MySQL does not allow for prefix indexing.
Prefix Length Too Long
The specified prefix length for the index is greater than the maximum allowed length of the actual column or the column's defined length.
Storage Engine Restriction
The chosen storage engine (e.g., MEMORY, NDB) does not support unique prefix keys, or has specific limitations regarding their use.
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