right now, FaissKnnVectorsFormat only supports DOT_PRODUCT and EUCLIDEAN. If we try to use COSINE, it fails at runtime with an UnsupportedOperationException. since cosine similarity is commonly used, and Lucene already supports it we should add it. also, the base test suite (BaseKnnVectorsFormatTestCase) includes cosine, so Faiss isn’t really on par with other formats like HNSW yet.
right now, FaissKnnVectorsFormat only supports DOT_PRODUCT and EUCLIDEAN. If we try to use COSINE, it fails at runtime with an UnsupportedOperationException. since cosine similarity is commonly used, and Lucene already supports it we should add it. also, the base test suite (BaseKnnVectorsFormatTestCase) includes cosine, so Faiss isn’t really on par with other formats like HNSW yet.