Here are the methods exposed by the OnlineStore interface, along with the core functionality supported by the method:
online_write_batch: write feature values to the online store
online_read: read feature values from the online store
update: update infrastructure (e.g. tables) in the online store
teardown: teardown infrastructure (e.g. tables) in the online store
plan: generate a plan of infrastructure changes based on feature repo changes
There is also additional functionality not properly captured by these interface methods:
support for on-demand transforms
readable by Python SDK
readable by Java
readable by Go
support for entityless feature views
support for concurrent writing to the same key
support for ttl (time to live) at retrieval
support for deleting expired data
Finally, there are multiple data models for storing the features in the online store. For example, features could be:
collocated by feature view
collocated by feature service
collocated by entity key
See this issue for a discussion around the tradeoffs of each of these data models.
There are currently five core online store implementations: SqliteOnlineStore, RedisOnlineStore, DynamoDBOnlineStore, SnowflakeOnlineStore, and DatastoreOnlineStore. There are several additional implementations contributed by the Feast community (PostgreSQLOnlineStore, HbaseOnlineStore, and CassandraOnlineStore), which are not guaranteed to be stable or to match the functionality of the core implementations. Details for each specific online store, such as how to configure it in a feature_store.yaml, can be found here.
Below is a matrix indicating which online stores support what functionality.
| Sqlite | Redis | DynamoDB | Snowflake | Datastore | Postgres | Hbase | Cassandra | |
|---|---|---|---|---|---|---|---|---|
write feature values to the online store
yes
yes
yes
yes
yes
yes
yes
yes
read feature values from the online store
yes
yes
yes
yes
yes
yes
yes
yes
update infrastructure (e.g. tables) in the online store
yes
yes
yes
yes
yes
yes
yes
yes
teardown infrastructure (e.g. tables) in the online store
yes
yes
yes
yes
yes
yes
yes
yes
generate a plan of infrastructure changes
yes
no
no
no
no
no
no
yes
support for on-demand transforms
yes
yes
yes
yes
yes
yes
yes
yes
readable by Python SDK
yes
yes
yes
yes
yes
yes
yes
yes
readable by Java
no
yes
no
no
no
no
no
no
readable by Go
yes
yes
no
no
no
no
no
no
support for entityless feature views
yes
yes
yes
yes
yes
yes
yes
yes
support for concurrent writing to the same key
no
yes
no
no
no
no
no
no
support for ttl (time to live) at retrieval
no
yes
no
no
no
no
no
no
support for deleting expired data
no
yes
no
no
no
no
no
no
collocated by feature view
yes
no
yes
yes
yes
yes
yes
yes
collocated by feature service
no
no
no
no
no
no
no
no
collocated by entity key
no
yes
no
no
no
no
no
no