MariaDB schema uses char(0) columns on HAOS despite correct mysqlclient setup

[haysdb]

The problem

The problem

On Home Assistant OS (HAOS) with the official MariaDB add-on, Home Assistant creates a broken schema with char(0) fields such as entity_id, last_updated, and attributes.

This suggests that Home Assistant is falling back to pymysql instead of using mysqlclient, even though HAOS includes mysqlclient by default and I'm using a mysql:// connection string (not pymysql://).

(ChatGPT wrote this. I personally have no idea. )

What version of Home Assistant Core has the issue?

core-2025.4.4

What was the last working version of Home Assistant Core?

Unknown — this is a new MariaDB installation.

What type of installation are you running?

Home Assistant OS

Integration causing the issue

recorder

Link to integration documentation on our website

No response

Diagnostics information

core_mariadb_2025-05-05T11-54-26.559Z.log

Example YAML snippet

### Example configuration.yaml


recorder:
  db_url: mysql://homeassistant:password@core-mariadb/homeassistant?charset=utf8mb4
  purge_keep_days: 35
  auto_purge: true

Anything in the logs that might be useful for us?

After stopping Home Assistant, dropping the homeassistant database, recreating it, and restarting HA, the following schema is created:

CREATE TABLE `states` (
  `state_id` bigint(20) NOT NULL AUTO_INCREMENT,
  `entity_id` char(0) DEFAULT NULL,
  `state` varchar(255) DEFAULT NULL,
  `attributes` char(0) DEFAULT NULL,
  `event_id` smallint(6) DEFAULT NULL,
  `last_changed` char(0) DEFAULT NULL,
  `last_updated` char(0) DEFAULT NULL,
  ...
);

Note that multiple fields are char(0), making queries fail (e.g., MIN(last_updated) returns null).

Additional information

I installed the MariaDB add-on via the Add-on Store This was a clean install The homeassistant database is created with charset utf8mb4 and collation utf8mb4_unicode_ci This issue occurs even after dropping and recreating the database

Suggested next steps Ensure mysqlclient is properly detected and used in HAOS Add a diagnostic warning if schema is being created with char(0) fields Confirm that pymysql is not being silently used on HAOS