By default the schema search path for a PostgreSQL database is going to be "$user", public. Tables created by a Rails migration are going to end up on the public schema by default. If your application has other schemas in play, then you may want to ensure that those schemas are also on the schema search path. This can be accomplished by adding the schema_search_path setting to your database.yml file. For instance, to include both the legacy and public schema in the Postgres search path, add the following line:

schema_search_path: "legacy,public"

h/t Jack Christensen