Which method is not recommended for making fields searchable in the User object?

Creating a new database table for fields in the User object is not a recommended approach for making those fields searchable. This method would involve significant overhead, including managing the new database schema and ensuring that the data in this custom table remains in sync with the User object, which could complicate maintenance and data integrity.

In the context of Liferay, the recommended practices focus more on utilizing existing features and extending existing functionality rather than creating additional complexity with new database tables. The other options involve utilizing Liferay's established plugin architecture and indexing capabilities, allowing for a more efficient integration within the framework.

By overriding the User service with a hook plugin, extending the User indexer, or implementing an indexer post processor, you can seamlessly integrate additional searchable fields into the existing User indexing system. This ensures that the standard processes remain intact while enhancing search capabilities without unnecessary complexity, thus promoting better maintainability and performance within the Liferay environment.