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Per-value hash¤

The Per-value hash operator hashes each input value independently and returns one hash per value. The output count always equals the input count — cardinality is preserved.

SPARQL alignment¤

This operator produces the same output as the SPARQL 1.1 hash functions applied per value. For a single input value, SHA256(?x) in SPARQL returns the same result as this operator with the default SHA256 algorithm.

Single-input constraint¤

The operator accepts exactly one input port. Connecting more than one port throws an IllegalArgumentException. This constraint exists because per-value hashing is defined relative to a single value sequence — combining values across ports would require choosing a port-merging strategy, which is the behaviour of the Combined input hash operator instead.

Output¤

Each input value produces one lowercase hexadecimal hash string. The output order matches the input order. If the input is empty, the output is empty — no hash is produced.

Values are encoded as UTF-8 before hashing.

Algorithm parameter¤

The algorithm parameter selects the hash function. The default is SHA-256. The five algorithms from the SPARQL 1.1 specification are supported:

SPARQL name Java name Notes
MD5 MD5 Weak — vulnerable to collision attacks. Avoid for security-sensitive use.
SHA1 SHA-1 Weak — deprecated for most security purposes.
SHA256 SHA-256 Recommended default.
SHA384 SHA-384 Stronger than SHA-256.
SHA512 SHA-512 Strongest in the SPARQL set.

Additional algorithms available on the JVM are also accepted. The full list is JVM-dependent and visible in the algorithm parameter dropdown.

Note that the Java names use hyphens (SHA-256, SHA-1) where SPARQL uses none (SHA256, SHA1). Both forms are accepted by this operator.

Contrast with Combined input hash¤

The Combined input hash operator feeds all values from all ports into a single hash function and returns one hash regardless of input size. Use it when you need a single fingerprint for a set of values taken together.

Use Per-value hash when each value needs its own hash — for example, to hash a column of URIs independently, or to replicate SHA256(?x) in SPARQL.

Examples¤

Notation: List of values are represented via square brackets. Example: [first, second] represents a list of two values “first” and “second”.

Single value produces one SHA-256 hash:

  • Input values:

    1. [input value]

  • Returns: [f708c2afff0ed197e8551c4dd549ee5b848e0b407106cbdb8e451c8cd1479362]

Two values in, two independent hashes out — one per value, not a combined hash:

  • Input values:

    1. [apple, banana]

  • Returns: [3a7bd3e2360a3d29eea436fcfb7e44c735d117c42d1c1835420b6b9942dd4f1b, b493d48364afe44d11c0165cf470a4164d1e2609911ef998be868d46ade3de4e]

The algorithm parameter selects the hash function (MD5), single value:

  • Parameters

    • algorithm: MD5

  • Input values:

    1. [apple]

  • Returns: [1f3870be274f6c49b3e31a0c6728957f]

The algorithm parameter selects the hash function (MD5), multiple values:

  • Parameters

    • algorithm: MD5

  • Input values:

    1. [apple, banana]

  • Returns: [1f3870be274f6c49b3e31a0c6728957f, 72b302bf297a228a75730123efef7c41]

The algorithm parameter selects the hash function (SHA-1):

  • Parameters

    • algorithm: SHA-1

  • Input values:

    1. [apple]

  • Returns: [d0be2dc421be4fcd0172e5afceea3970e2f3d940]

The algorithm parameter selects the hash function (SHA-384):

  • Parameters

    • algorithm: SHA-384

  • Input values:

    1. [apple]

  • Returns: [3d8786fcb588c93348756c6429717dc6c374a14f7029362281a3b21dc10250ddf0d0578052749822eb08bc0dc1e68b0f]

The algorithm parameter selects the hash function (SHA-512):

  • Parameters

    • algorithm: SHA-512

  • Input values:

    1. [apple]

  • Returns: [844d8779103b94c18f4aa4cc0c3b4474058580a991fba85d3ca698a0bc9e52c5940feb7a65a3a290e17e6b23ee943ecc4f73e7490327245b4fe5d5efb590feb2]

Empty input produces empty output:

  • Input values:

    1. []

  • Returns: []

Two input ports causes IllegalArgumentException:

  • Input values:

    1. [foo]
    2. [bar]

  • Returns: []

  • Throws error: IllegalArgumentException

Invalid algorithm name causes NoSuchAlgorithmException:

  • Parameters

    • algorithm: NONEXISTENT

  • Input values:

    1. [foo]

  • Returns: []

  • Throws error: NoSuchAlgorithmException

Empty algorithm string causes IllegalArgumentException:

  • Parameters

    • algorithm: ``

  • Input values:

    1. [foo]

  • Returns: []

  • Throws error: IllegalArgumentException

Parameter¤

Algorithm¤

The hash algorithm to be used.

  • ID: algorithm
  • Datatype: string
  • Default Value: SHA256

Advanced Parameter¤

None

  • inputHash — The Combined input hash plugin produces one combined hash for all input values. The Per-value hash plugin instead hashes each value independently, preserving cardinality.

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