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DuckDB Extensions All extensions Hashfuncs

xxHash functions in the Hashfuncs DuckDB extension

Function category

xxHash

5 functions

Yann Collet's xxHash family — among the fastest non-cryptographic hashes available, with excellent distribution. xxh3_64 is a sensible modern default; the 128-bit variants (xxh3_128, xxh3_128_hex) give you more headroom against accidental collisions and a portable hex digest format used by Python xxhash and xxhash-rust.

xxh3_128

Scalar function xxHash
Signature
2 overloaded forms · click to inspect
Arguments (Positional)
Argument value Type ANY Mode Positional Description
Description

128-bit xxHash3 (XXH3_128) returned as a UHUGEINT. The wider hash space dramatically reduces accidental-collision probability for very large keyspaces (billions of distinct keys).

Use when 64 bits feels tight — content fingerprints, dedup keys at scale, or any place a 64-bit birthday-bound starts to matter. For a portable hex digest instead of a number, use xxh3_128_hex.

For stored-key compatibility, this numeric function keeps its historical half ordering. Its formatted hex is not canonical; use xxh3_128_hex on corrected builds, or exchange the two 16-character halves of its zero-padded 32-character hex.

1 128-bit hash 
SELECT xxh3_128('hello world');

Output

xxh3_128('hello world')
225447084758876380551077147957698971904
2 Seeded 
SELECT xxh3_128('hello world', 42);

Output

xxh3_128('hello world', 42)
173805935617512661584987041130904516770
Related functions

xxh3_128_hex

Scalar function xxHash
Signature
4 overloaded forms · click to inspect
Arguments (Positional)
Argument col0 Type BLOB Mode Positional Description
Description

128-bit xxHash3 returned as a 32-character lowercase hex string in canonical xxHash byte order (high64 || low64), as defined by the xxHash specification.

Matches the digest produced by XXH128_canonicalFromHash in C, xxhash.xxh3_128().hexdigest() in Python, and xxhash-rust when formatted as hex. Use it when the hash needs to be a string — Redis keys, filenames, or a fingerprint shared with non-SQL code.

The v1.5 source fix dated October 7, 2026 corrects earlier reversed-half output, including build 0dec806. Community packages may lag; xxh3_128_hex('hello') must return b5e9c1ad071b3e7fc779cfaa5e523818. Previously stored affected hex digests require a one-time half swap. Numeric xxh3_128 results remain unchanged.

1 32-char hex digest 
SELECT xxh3_128_hex('hello');

Output

xxh3_128_hex('hello')
b5e9c1ad071b3e7fc779cfaa5e523818
2 Seeded variant 
SELECT xxh3_128_hex('hello', 42);

Output

xxh3_128_hex('hello', 42)
6ce89a0bdba81f088c2f5b7e4cd59e16
Related functions

xxh3_64

Scalar function xxHash
Signature
2 overloaded forms · click to inspect
Arguments (Positional)
Argument value Type ANY Mode Positional Description
Description

64-bit xxHash3 (XXH3_64) — the modern xxHash variant tuned for vectorized CPUs (SSE2/AVX2). Faster than xxh64 on virtually all modern hardware, especially for short inputs, with comparable distribution quality.

This is the recommended general-purpose 64-bit non-cryptographic hash for partitioning, sharding, deduplication, and as input to probabilistic filters in bitfilters.

1 Default unseeded 
SELECT xxh3_64('hello world');

Output

xxh3_64('hello world')
15296390279056496779
2 Seeded for partitioning 
SELECT xxh3_64('hello world', 999);

Output

xxh3_64('hello world', 999)
3002856137354040482
Related functions

xxh32

Scalar function xxHash
Signature
2 overloaded forms · click to inspect
Arguments (Positional)
Argument value Type ANY Mode Positional Description
Description

32-bit xxHash (XXH32) — the classic 32-bit member of the xxHash family. Fast and well-distributed; use when 32 bits is enough — for in-memory hashtables, lightweight checksums, or short-lived bucket assignment.

Accepts an optional UINTEGER seed. Prefer xxh3_64 when you don't have a specific reason to use the 32-bit format — XXH3 is faster on modern hardware and offers more headroom against collisions.

1 Hash a string 
SELECT xxh32('hello world');

Output

xxh32('hello world')
3468387874
2 Seeded variant — independent hash space 
SELECT xxh32('hello world', 42);

Output

xxh32('hello world', 42)
4225033588
Related functions

xxh64

Scalar function xxHash
Signature
2 overloaded forms · click to inspect
Arguments (Positional)
Argument value Type ANY Mode Positional Description
Description

64-bit xxHash (XXH64). The original 64-bit xxHash — broadly supported across language bindings and on-the-wire identical to xxHash 0.6.x callers.

Pick xxh64 when you must match an existing XXH64-based system; otherwise xxh3_64 is faster on modern CPUs.

1 64-bit hash of a string 
SELECT xxh64('hello world');

Output

xxh64('hello world')
5020219685658847592
2 Seeded 
SELECT xxh64('hello world', 42);

Output

xxh64('hello world', 42)
7620854247404556961
Related functions