lcsh-db-ft — LCSH authority DB embedded with fine-tuned EmbeddingGemma

lcsh.db — a SQLite + sqlite-vec database of Library of Congress authorities, with the LCSH + LCGFT vector index built from the LCSH-fine-tuned EmbeddingGemma-300M (256-d). The companion to the embedder kltng/embeddinggemma-300m-lcsh-onnx; intended for an on-device / Chrome-extension subject-cataloging workflow.

Parallel to the stock-embedded kltng/lcsh-db; only the auth_embeddings vectors differ (fine-tuned instead of stock EmbeddingGemma).

Contents

Table	Rows	Notes
auth	LCSH 512,644 · LCGFT 2,637 · LCNAF 12,255,750	authority records
alt_label	—	UF / variant labels
auth_embeddings (vec0)	916,142	LCSH+LCGFT labels + alt-labels, 256-d float32
auth_fts, alt_label_fts	—	FTS5 for exact/fuzzy string lookup

db_meta.embedding_model = kltng/embeddinggemma-300m-lcsh-onnx. LCNAF names are present for exact/FTS lookup but not embedded (same policy as the stock db).

Query (must use the matching embedder)

Embed the query with kltng/embeddinggemma-300m-lcsh-onnx, truncate to 256-d, L2-normalize, then KNN:

SELECT auth_id, distance FROM auth_embeddings WHERE embedding MATCH :qvec AND k = 10;
-- then join auth_id -> auth.label

Use fp16 for the closest parity to the build vectors (cos ≈ 0.999); q8 (smallest, what these vectors were spot-checked against) is also fine (cos ≈ 0.97).

License

Vectors derived from google/embeddinggemma-300m — Gemma Terms of Use. LCSH/LCGFT/LCNAF authority data is from the Library of Congress (public domain).