pgvector 0.7+ Knowledge Patch

Claude's baseline knowledge covers pgvector through 0.6.x. This skill provides features from 0.7.0 (Apr 2024) onwards.

Source: pgvector GitHub at https://github.com/pgvector/pgvector

Reference Files

• references/vector-types-and-indexing.md — halfvec, sparsevec, bit indexing, binary quantization, expression indexes, subvector extraction
• references/iterative-index-scans.md — iterative scan modes, overfiltering solutions, scan limits, CTE patterns

Quick Reference: New Vector Types (0.7.0)

Type	Description	Max Indexed	Format
halfvec(n)	Half-precision (float16) vectors	4,000 dims	Same as vector
sparsevec(n)	Sparse vectors	1,000 non-zero	'{1:val,3:val}/dims' (1-indexed)
bit(n) indexing	Binary vector search	64,000 dims	Standard bit type

Quick Reference: New Functions (0.7.0)

Function	Purpose
binary_quantize(vector)	Convert vector to bit (positive -> 1, else -> 0)
subvector(vector, start, length)	Extract subvector (1-indexed)
l2_normalize(vector)	L2 normalize a vector
vector || vector	Concatenate vectors

Quick Reference: New Operator Classes (0.7.0)

Type	L2	Inner Product	Cosine
halfvec	halfvec_l2_ops	halfvec_ip_ops	halfvec_cosine_ops
sparsevec	sparsevec_l2_ops	sparsevec_ip_ops	sparsevec_cosine_ops

Type	Hamming (<~>)	Jaccard (<%>)
bit	bit_hamming_ops	bit_jaccard_ops

HNSW now also supports L1 distance with vector_l1_ops.

Quick Reference: Iterative Index Scans (0.8.0)

Solves the "overfiltering" problem — when WHERE clauses with approximate indexes return too few results.

-- Enable for HNSW (strict = exact distance order; relaxed = better recall)
SET hnsw.iterative_scan = strict_order;  -- or relaxed_order
SET hnsw.max_scan_tuples = 20000;        -- default; max tuples to visit

-- Enable for IVFFlat (relaxed_order ONLY — no strict_order support)
SET ivfflat.iterative_scan = relaxed_order;
SET ivfflat.max_probes = 100;            -- max probes for iterative scans

Half-Precision Expression Index (0.7.0)

CREATE INDEX ON items USING hnsw ((embedding::halfvec(3)) halfvec_l2_ops);
SELECT * FROM items ORDER BY embedding::halfvec(3) <-> '[1,2,3]' LIMIT 5;

Binary Quantization Expression Index (0.7.0)

CREATE INDEX ON items USING hnsw ((binary_quantize(embedding)::bit(3)) bit_hamming_ops);
-- Re-rank for better recall:
SELECT * FROM (
    SELECT * FROM items ORDER BY binary_quantize(embedding)::bit(3) <~> binary_quantize('[1,-2,3]') LIMIT 20
) ORDER BY embedding <=> '[1,-2,3]' LIMIT 5;

Iterative Scan CTE Patterns (0.8.0)

Materialized CTE for strict ordering with relaxed scans:

WITH relaxed_results AS MATERIALIZED (
    SELECT id, embedding <-> '[1,2,3]' AS distance FROM items
    WHERE category_id = 123 ORDER BY distance LIMIT 5
) SELECT * FROM relaxed_results ORDER BY distance + 0;

Note: + 0 is needed for Postgres 17+ to force re-sorting.

Distance filter pattern (place distance filter outside CTE):

WITH nearest AS MATERIALIZED (
    SELECT id, embedding <-> '[1,2,3]' AS distance FROM items ORDER BY distance LIMIT 5
) SELECT * FROM nearest WHERE distance < 5 ORDER BY distance;

Array to sparsevec Cast (0.8.0)

SELECT ARRAY[1,0,2,0,3]::sparsevec;  -- '{1:1,3:2,5:3}/5'