oxi-gen

A high-performance command-line tool for converting CSV/TSV files to RDF (Turtle or N-Triples) using SPARQL CONSTRUCT queries. Inspired by Tarql, oxi-gen is built in Rust on top of the Oxigraph stack and leverages multi-threaded processing to handle large datasets efficiently.

Each row of the input CSV is bound as SPARQL variable substitutions and evaluated against a CONSTRUCT query, producing RDF output. Column headers become variable names (e.g., a name column is available as ?name), and the special variable ?ROWNUM holds the current row index.

Command-Line Options

oxi_gen -q <QUERY> [OPTIONS]

Option	Short	Description
--query <FILE>	-q	SPARQL CONSTRUCT query file to apply (required)
--input <FILE>	-i	Input CSV file. Omit to read from STDIN
--output <FILE>	-o	Output file. Omit to write to STDOUT
--delimiter <CHAR>	-d	CSV delimiter character (default: ,)
--tab	-t	Treat input as tab-separated (TSV)
--no-header-row	-H	Input has no header row; columns are named a–z, A–Z
--normalize	-n	Normalize column names to UPPERCASE
--escape_char <CHAR>	-p	Escape character (default: \)
--quote_char <CHAR>		Quote character (default: ")
--ntriples		Output N-Triples instead of Turtle
--gzip	-g	Gzip the output (requires --output)
--dedup[=N]		Deduplicate triples within a sliding window (default window: 1000, range: 1000–5000000)
--test[=N]		Process only the first N rows for testing (default: 5, max: 49)
--split <ORIGINAL> <SPLIT> <DELIMITER>		Split column ORIGINAL on DELIMITER, binding each value to SPLIT. Can be repeated
--bind-empty-strings		Bind empty CSV values as empty string literals instead of skipping them

Custom SPARQL Functions

oxi-gen registers two custom functions under the tarql: prefix (https://semanticarts.com/tarql/):

• tarql:expandPrefix(?prefix) — returns the IRI for a given prefix name declared in the query.
• tarql:expandPrefixedName(?qname) — expands a prefixed name (e.g., "foaf:name") into a full IRI node.

Building from Source

Prerequisites

• Rust (1.85+ required for edition 2024)

Build a release binary

git clone git@github.com:semanticarts/oxi-gen.git
cd oxi-gen
cargo build --release

The optimized binary will be at target/release/oxi_gen. The release profile is configured with LTO, single codegen unit, and abort-on-panic for maximum performance.

Run directly with Cargo

cargo run --release -- -q query.sparql -i data.csv -o output.ttl