Redshift does not support multiple entities

[woop]

Expected Behavior

Feast supports multiple entities with Redshift sources

Current Behavior

When a feature requires more than 1 entities, Feast will throw error upon retrieving feature. It throws the follow error:

ERROR: function concat(character varying, character varying, character varying) does not exist\n  Hint: No function matches the given name and argument types. You may need to add explicit type casts.

The reason is, redshift CONCAT only support 2 arguments. you might want consider the concat operator or nested concat