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RDF4J 4.2.0 is a minor release introducing support for custom SPARQL aggregate functions as well as several performance improvements and bug fixes.

Aggregate functions

The support for custom SPARQL aggregate functions has allowed us to implement functions for standard deviation and variance using Apache Commons Math3.

IRI Description Standard deviation using sampling. Standard deviation using statistical population. Variance using sampling. Variance using statistical population.

Query example

SELECT (<>(?o) AS ?stdev) WHERE { 
    ?s ?p ?o .


More accurate query statistics for the LMDB Store drastically improves query performance. The LMDB Store can already scale to considerably larger datasets than the NativeStore and now also matches the performance for smaller datasets.

Validation performance for small transactions on large databases has been improved by batching together more operations when analyzing the changes in a transaction.

For a complete overview, see all issues fixed in 4.2.0.

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