The MySQL online store provides support for materializing feature values into a MySQL database for serving online features.

• Only the latest feature values are persisted

In order to use this online store, you'll need to run pip install 'feast[mysql]'. You can get started by then running feast init and then setting the feature_store.yaml as described below.

{% code title="feature_store.yaml" %}

project: my_feature_repo
registry: data/registry.db
provider: local
online_store:
    type: mysql
    host: DB_HOST
    port: DB_PORT
    database: DB_NAME
    user: DB_USERNAME
    password: DB_PASSWORD

{% endcode %}

The full set of configuration options is available in MySQLOnlineStoreConfig.

By default, the MySQL online store performs row-by-row insert and commit for each feature record. While this ensures per-record atomicity, it can lead to significant overhead on write operations — especially on distributed SQL databases (for example, TiDB, which is MySQL-compatible and uses a consensus protocol).

To improve writing performance, you can enable batch write mode by setting batch_write to true and batch_size, which executes multiple insert queries in batches and commits them together per batch instead of committing each record individually.

{% code title="feature_store.yaml" %}

project: my_feature_repo
registry: data/registry.db
provider: local
online_store:
    type: mysql
    host: DB_HOST
    port: DB_PORT
    database: DB_NAME
    user: DB_USERNAME
    password: DB_PASSWORD
    batch_write: true
    batch_size: 100

{% endcode %}

The set of functionality supported by online stores is described in detail here. Below is a matrix indicating which functionality is supported by the Mys online store.

To compare this set of functionality against other online stores, please see the full functionality matrix.