irelink

• Composition: cl_levels(), cl_and(), cl_or(), cl_not(), cl_null(), cl_else(), cl_literal(), cl_custom(), cl_columns_reversed().
• All applicable comparators accept term_frequency = TRUE for Fellegi-Sunter term-frequency adjustments.

Column transforms

• il_transform() composes multiple R functions into a chainable transform with SQL-side nesting (e.g. TRIM(LOWER(col))).
• Column transform factories for SQL-side column expressions: il_substr(), il_regex_extract(), il_nullif(), il_cast_to_string(), il_try_parse_date(), il_array_element().
• Built-in transforms auto-translated to SQL: tolower, toupper, trimws.
• Phonetic transforms: il_soundex(), il_metaphone(), il_dmetaphone() (usable as R functions and SQL macros).

Blocking

• il_block_on() and block_on() for equality-based and custom SQL blocking rules, with per-column transform support via formula syntax (col ~ transform, e.g. first_name ~ il_substr(1, 3)) or a named-list .transform for programmatic construction.
• .explode parameter for array-valued blocking columns (generates UNNEST subqueries for DuckDB).
• il_count_pairs() counts candidate pairs, including cumulative totals and percent-of-cartesian summaries across rule combinations, and can estimate counts from a deterministic record sample on large data through record_sample_proportion.
• il_suggest_blocking() ranks candidate blocking rules by pair-reduction, coverage, and balanced score.
• il_find_blocking_below() finds blocking rule combinations below a pair count ceiling.
• block_from_labels() measures per-column recall from labeled pairs.
• il_largest_blocks() identifies the blocking keys that generate the most records and pairs, respecting blocking transforms.

Training

• il_estimate_u() estimates non-match probabilities from all candidate pairs when there are at most max_pairs, and otherwise from a uniform random sample of records (reproducible with set.seed()), with optional chunked estimation over random chunks through chunk_size and early stopping through min_count_per_level.
• il_estimate_em() runs the Fellegi-Sunter EM algorithm with configurable max_iterations, convergence, fix_u, fix_m, fix_prior, derive_prior, estimate_without_tf, and estimator_mode parameters. An optional max_pairs cap trains on a deterministic record sample sized to produce about that many blocked pairs.
• estimator_mode = "dependency-aware" fits log-linear matched and unmatched comparison-pattern distributions over aggregated gamma counts, preserving missing comparison states as explicit pattern levels.
• il_estimate_prior() sets the prior match probability from deterministic matching rules, counting unique blocked pairs across overlapping rules, optionally from a deterministic record sample through record_sample_proportion.
• il_prior_prevalence() and il_prior_m() add regularizing custom priors for EM, il_constrain_m() adds explicit fixed matched-class constraints, and il_priors() / il_constraints() expose the stored metadata.
• il_estimate_m_from_labels() and il_estimate_m_from_column() initialize parameters from ground-truth labels.

Prediction

• predict() supports both threshold (match probability) and threshold_match_weight (evidence-only log2 Bayes factor) filtering.
• Prediction output includes evidence-only match_weight, prior-inclusive total_match_weight, and posterior match_probability.
• predict(type = "weights") returns match weights on the log2 Bayes-factor scale, and greedy = TRUE adds deterministic one-to-one post-processing for link models.
• include_fields = TRUE joins all source columns into the scored output.
• collect = FALSE returns an il_compared_lazy object backed by a model-scoped in-database table.
• il_score_missing_edges() enumerates and scores unscored within-cluster pairs.
• il_score_pairs() scores every pair between two sets of records with a trained model, without blocking, using the model's own term-frequency tables.
• il_score_patterns() scores compatible comparison-pattern tables, including dependency-aware pattern tables larger than the table used for fitting.
• il_deterministic_link() performs single-table exact-match deduplication without training.
• il_find_matches() scores a set of probe records against existing data.
• profile_sql = TRUE on predict() attaches lightweight SQL timing metadata to collected predictions or lazy prediction objects, and lazy objects keep it when collected. Profiling adds no overhead when disabled.

Diagnostics and evaluation

• il_parameters() and il_weights() expose the learned m/u parameters.
• il_waterfall() decomposes a pair's match weight into per-comparison contributions.
• il_training_history() tracks parameter convergence across EM iterations.
• il_completeness() and il_profile() summarize data quality, and il_profile() accepts raw SQL expressions as column definitions (e.g., "city || left(first_name, 1)").
• il_unlinkables() identifies records that cannot be linked under any blocking rule.
• il_accuracy(), il_precision_recall(), and il_roc() evaluate performance against labeled data.
• il_errors() surfaces false positives and false negatives.
• il_graph_metrics() computes node degree, node centrality, cluster density, cluster centralization, and bridge detection.
• il_comparison_vectors() returns the gamma pattern distribution from a trained model.

Data exploration

• il_compare_records() computes comparison levels for one explicit record pair against a spec without fitting a model, and il_string_similarity() computes 5 string similarity metrics for a single pair.
• il_comparator_score() computes batch string similarity across a data frame with SQL-side scoring on DuckDB.
• il_comparator_threshold_chart() visualizes match rates at multiple similarity thresholds.
• il_phonetic_chart() produces a Soundex agreement heatmap.
• il_tf_chart() visualizes model-specific term frequency distributions with labeled most/least common values.
• il_register_tf() registers pre-computed term frequency tables in the database and returns the updated model.

Visualization

• autoplot() methods for il_model, il_compared, il_training_history, il_accuracy, il_roc, il_precision_recall, il_unlinkables, il_completeness, il_count_pairs, il_profile, il_string_similarity, il_comparator_score, and il_comparison_vectors.
• All chart types are composable with standard ggplot2 layers.

Datasets

• fake_1000: 1,000 records (250 entities) for deduplication.
• fake_1000_labels: 3,176 pairwise labels for evaluation.
• fake_20: minimal 20-record example.
• febrl4a / febrl4b: 5,000-record cross-table linkage benchmark from FEBRL.

SQL backends and persistence

• All computation runs inside a DBI-compatible database: DuckDB (recommended) or SQLite.
• Database-backed workflows support zero-copy registration from dbplyr::tbl_lazy references and existing table names, in addition to in-memory data frames.
• il_save() and il_load() support both RDS files and Splink settings JSON.
• il_attach() reattaches a saved model to different data or connections.
• il_cleanup() removes temporary tables owned by a single model, making it safe for shared DBI connections with multiple live models.
• il_cleanup_all() removes all package-owned temporary tables from a connection for exploratory sessions and failed runs.

Performance

• Gamma computation is pushed into DuckDB using native C++ string similarity functions.
• SQLite is retained as a fallback with R-side gamma computation via stringdist.
• DuckDB uses SQL-native connected components, with an igraph fallback for SQLite.
• Term-frequency, lazy prediction, and scratch tables use generated model-scoped names to avoid collisions on shared connections.
• profile_sql = TRUE on il_estimate_u(), il_estimate_prior(), and predict() records lightweight SQL timing metadata for performance investigation.
• options(irelink.show_sql = TRUE) prints every SQL statement irelink sends to the database, formatted for reading.
• End-to-end benchmarks against an R-side SQLite baseline: 1,000 records in 1.4 s (2.1× faster), 5,000 records in 19.5 s (1.6×), 10,000 records in 61.4 s (2.6×). Speedup grows with dataset size.