Which transformer would be most appropriate to join two streams of features from non-database formats?

• A. DatabaseJoiner
• B. InlineQuerier
• C. FeatureJoiner
• D. Merger

Answer: (C)

Joining two feature streams from non-database formats is about combining attributes from two separate inputs based on a shared key, without involving any external database. The FeatureJoiner is designed exactly for this scenario: it takes two inputs, matches features on specified join fields, and outputs features that carry attributes from both sides for those matches. This in-memory join works well when both sources are non-database formats, and you can choose how to handle non-matching features (inner, left, or outer join) as needed.

Why this fits best: you’re not querying or pulling data from a database; you want a direct, on-the-fly combination of two streams, preserving or aligning attributes as configured. The other options don’t fit as cleanly: a DatabaseJoiner requires a database table to join with, InlineQuerier is for querying data sources rather than merging two streams, and Merger simply concatenates streams without aligning features on a common key or merging their attributes.