--- title: "Blocking" summary: "Blocking is the technique that makes entity resolution affordable by comparing each record only against a small set of plausible candidates instead of against every other record." canonical_url: https://entitybind.com/glossary/blocking last_updated: 2026-10-15 copy: full --- # Blocking > Blocking is the technique that makes entity resolution affordable by comparing each record only against a small set of plausible candidates instead of against every other record. Canonical page: https://entitybind.com/glossary/blocking Last updated: 2026-10-15 Glossary · Matching methods ## How to read this The definition as the field writes it comes first, weaknesses and all. What Entity Bind does about it comes last, in its own paragraph, so you can take one without the other. [Filed under matching methods](https://entitybind.com/glossary#matching). By [James Rooney](https://entitybind.com/about), founder of Entity Bind · Last revised 15 October 2026 ## What blocking means Blocking is the step that decides which pairs are worth comparing at all. Comparing every record against every other is quadratic: a million records is five hundred billion pairs, and no scorer is cheap enough for that. Blocking partitions or indexes the data so that only records sharing a blocking key are compared — the first four characters of the normalised name, the postcode, a phonetic code, a token, or several of these in parallel as separate passes. Every blocking scheme trades recall against cost. A tight key produces few pairs and misses true matches whose key differs by one character; a loose key produces so many pairs that the saving disappears. Multiple independent passes are the standard answer, because a true pair only has to survive one of them, and a record with a mistyped postcode can still be caught by its name pass. The crucial property is that blocking sets a ceiling on everything downstream. A true match that never becomes a candidate cannot be recovered by any scorer, however good — which is why blocking recall is measured separately from match accuracy, and why an accuracy figure quoted without a retrieval figure is quoting the second half of a pipeline. Entity Bind weights every blocking key by how rare the token is across the catalogue and the live registers — 'services' is worthless as a key, 'Vodafone' is decisive — which is what rarity-weighted blocking means, and it measures retrieval recall as a metric in its own right. Treating those two tokens equally spends the candidate budget on the wrong records. ## Where this shows up in Entity Bind Three pages where this term stops being vocabulary and starts changing an answer, a payload or a price. - [Blocking and candidate generation](https://entitybind.com/guides/blocking-and-candidate-generation): Comparing every record against every other record is quadratic and therefore impossible at any real scale. That stage is blocking, also called indexing or candidate… - [How it works](https://entitybind.com/how-it-works): The seven-stage cascade in order, what each stage can settle on its own, and what it hands to the next. - [The accuracy method](https://entitybind.com/accuracy): Every published rate with the population it was measured over, its interval and its fixture — including the input shapes that fail. The fastest way past a definition is a file: which of your rows are the same company, which of your existing matches we would not have made, and what we could not decide. [Start free →](https://app.entitybind.com/app?signup=1) ## The terms next to this one Each with its own sentence, because the next question is usually about the word beside this one. - [Candidate generation](https://entitybind.com/glossary/candidate-generation): Candidate generation is the retrieval step that proposes the small set of entities a record might be, and its recall is the hard ceiling on everything the rest of the pipeline can achieve. - [Recall@k](https://entitybind.com/glossary/recall-at-k): Recall@k is the share of records for which the correct entity appears anywhere in the top k candidates returned by retrieval, and it is the ceiling on everything a matcher downstream can get right. - [Recall](https://entitybind.com/glossary/recall): Recall is the share of the true matches present in the data that a system actually found, and it is the metric that abstention costs you. - [Normalisation](https://entitybind.com/glossary/normalisation): Normalisation rewrites a record into a comparable form — case, punctuation, legal forms, identifier shapes — before any comparison is attempted, and it is where most of the achievable accuracy in entity resolution is won or lost. - [Probabilistic matching](https://entitybind.com/glossary/probabilistic-matching): Probabilistic matching scores a candidate pair by weighing the agreement and disagreement of several fields into a single number, then applies thresholds to that number rather than to any one field. ### Answered at length elsewhere - [Splink](https://entitybind.com/compare/splink) (Comparison): Free, open source, and it weighs the evidence properly: Fellegi–Sunter, done right. Our scoring stage is the same family. ## The other 12 terms on this shelf How two records are compared and how the comparison is made cheap enough to run. Blocking, deterministic rules, probabilistic scoring, string distance. - [Normalisation](https://entitybind.com/glossary/normalisation) - [Transliteration](https://entitybind.com/glossary/transliteration) - [Candidate generation](https://entitybind.com/glossary/candidate-generation) - [Deterministic matching](https://entitybind.com/glossary/deterministic-matching) - [Probabilistic matching](https://entitybind.com/glossary/probabilistic-matching) - [Fellegi–Sunter](https://entitybind.com/glossary/fellegi-sunter) - [m-probability](https://entitybind.com/glossary/m-probability) - [u-probability](https://entitybind.com/glossary/u-probability) - [Match weight](https://entitybind.com/glossary/match-weight) - [Fuzzy matching](https://entitybind.com/glossary/fuzzy-matching) - [Edit distance](https://entitybind.com/glossary/edit-distance) - [Jaro–Winkler](https://entitybind.com/glossary/jaro-winkler) Previous, alphabetically: [Beneficial ownership](https://entitybind.com/glossary/beneficial-ownership) · Next, alphabetically: [Calibration](https://entitybind.com/glossary/calibration) ## Evidence basis Internal fixtures only. The historical 2026-08-29 per-tier recording covers 317 GB companies with identifier-rich arrivals seeding the catalogue first; the context tier includes country and registered-town prose. Its legacy replay has no full-prompt-verified calls and cannot certify current calibration. The September 5 CI reports cover 1,176 labelled pairs and 705 records over 250 companies using offline stubs. These are not independent customer holdouts or live production validation; the 99% minimum-input product target remains unmet. Scope is company and organisation identity only — not people, vessels, bank-account ownership, sanctions or emissions. Results may not be used for eligibility decisions about individuals, including employment, credit and tenancy. ## Start with your own company records. Create your workspace, verify your email and run your first company file. The Free plan needs no card. Create API keys in your workspace when you need an integration. [Start free](https://app.entitybind.com/app?signup=1) · [All 64 terms](https://entitybind.com/glossary) 300 credits. No card. For a guided review of your file, explore [the Merge Safety Sprint](https://entitybind.com/audit-pack). --- Entity Bind resolves companies and organisations only. It does not resolve people, vessels, bank-account ownership, sanctions exposure, emissions or geolocation, and its results may not be used for eligibility decisions about individuals, including employment, credit and tenancy. This is the Markdown copy of https://entitybind.com/glossary/blocking, assembled from the same data the page renders and carrying every sentence, table row, figure and question the page's main content carries. The HTML page is canonical; it adds the layout, the navigation and the interactive parts (the ask panel, the forms), which a copy can name but not run. Every page on the site, with a line on each: https://entitybind.com/llms.txt.