# MySQL 8.4 partition key indexed column prefix rejected CREATE ALTER TABLE warning error

Status: search-observed
Product: MySQL 8.4
Last verified: 2026-06-25
Canonical HTML: https://gitdocs.org/fix/mysql-8-4-partition-key-indexed-column-prefix-rejected-create-alter-table-warning-error
Machine JSON: https://gitdocs.org/api/fixes/mysql-8-4-partition-key-indexed-column-prefix-rejected-create-alter-table-warning-error.json

## Exact Symptom

See the observed Codex queries below.

## Diagnosis

Several historical response shapes are locally plausible; only the selected current API version determines fields, enums, media types, and status codes.

## Fix

```
Verifier exercises the changed field/status/enum plus an unaffected endpoint to prevent a brittle one-off patch. Check operational state and security, not a compatibility switch that weakens the server.
```

## Avoid

- Changing local code without checking the current external contract.
- Retrying the same install, build, or API call with no version/source change.
- Applying a broad unsafe bypass when a narrow compatibility fix is available.

## Observed Codex Queries

- MySQL 8.4 partition key indexed column prefix rejected CREATE ALTER TABLE warning error
- site:dev.mysql.com MySQL 8.4 partitioning column prefix index partition key error
- "Prefix columns in indexes are not supported for partitioning keys" MySQL
- "partitioning keys" "prefix" "MySQL" "warning"
- https://dev.mysql.com/doc/refman/8.4/en/partitioning-limitations.html
- 'prefix' in https://dev.mysql.com/doc/refman/8.4/en/partitioning-key.html

## Sources

- MySQL 8.4.0 release notes: https://dev.mysql.com/doc/relnotes/mysql/8.4/en/news-8-4-0.html
- Official reference opened by Codex: https://dev.mysql.com/doc/refman/8.4/en/partitioning-limitations.html