The storage engine cannot create an index on the specified column because its data type, length, or attributes are not supported.
MySQL Error 1167 (ER_WRONG_KEY_COLUMN) appears when InnoDB or another storage engine cannot index the chosen column, often due to an unsupported data type or length. Change the column type, shorten indexed length, or pick a different column, then rerun the ALTER or CREATE statement to resolve the issue.
The used storage engine can't index column '%s'
MySQL throws error 1167 when you attempt to define an index or primary key on a column that the active storage engine cannot support. The full message states: The used storage engine can't index column 'column_name'.
This error stops CREATE TABLE or ALTER TABLE statements until the underlying schema conflict is resolved.
Fixing it quickly matters because missing indexes hurt query performance and block deployments.
Unsupported column types such as TEXT, BLOB, JSON, or GEOMETRY cannot be fully indexed in most engines. Attempting to add them to an index raises ER_WRONG_KEY_COLUMN.
Excessive length on VARCHAR columns also triggers the error.
InnoDB limits the combined length of indexed columns to 3072 bytes.
Virtual columns referencing non-stored expressions, and columns declared NULL inside a primary key, produce the same failure.
First inspect the failing statement with SHOW CREATE TABLE or DESCRIBE to identify the problem column. Next either change the data type to an indexable one, shorten the length, or use a prefix index.
After adjusting the definition, rerun ALTER TABLE ... ADD INDEX or rebuild the table.
Always test in a staging environment before production rollout.
Adding an index on a 1,000-character UTF-8 VARCHAR(1000) column exceeds byte limits. Use VARCHAR(255) or a prefix index LIKE (column_name(191)).
Trying to index a JSON column fails. Instead, extract needed keys into generated persisted columns and index those.
Primary-keying a text column in MyISAM fails. Convert the column to CHAR or VARCHAR within length constraints.
Model columns with index plans in mind.
Keep VARCHAR sizes reasonable and use utf8mb4 with 191-byte prefixes for compatibility.
Validate schema changes with MySQL’s --dry-run tools or run Galaxy’s AI lint checks before deployment. Continuous integration tests should attempt table creation on a throw-away database.
Error 1071 key too long occurs when the combined index length exceeds engine limits. Reducing column size or indexing a prefix resolves it.
Error 1283 column cannot be part of key occurs when you include a non-stored generated column in a key.
Mark the column STORED or index the source column instead.
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Yes, but only by using a prefix index like TEXT(191) or by hashing the value into a separate column.
InnoDB limits the combined length of indexed columns to 3072 bytes. For utf8mb4 each character can consume 4 bytes.
Switching from MyISAM to InnoDB or vice versa rarely solves the problem because both engines share similar type restrictions.
Galaxy’s SQL editor analyzes CREATE and ALTER statements in real time, warning you if a column type or size exceeds index limits before the query runs.
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