Full-text search

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Full-text search (BM25)

Full-text search (BM25)

A full-text index over a (label, string-property) pair, ranked with BM25 (the Lucene/Tantivy default scoring). It is a reimplementation of the valuable core of Lucene — an analyzer pipeline, postings with term frequencies, and BM25 — not a dependency.

Declare

CREATE FULLTEXT INDEX ON :Article(body);
CREATE FULLTEXT INDEX ON :Article(body) LANGUAGE 'english';   // language hint
SHOW FULLTEXT INDEXES;

The index backfills existing string values and is maintained on every write. (The language hint is recorded for forward compatibility; v1 analyses as English.)

A list value is analysed per string element — nulls and non-string elements are skipped. A staged value like name: ['ACME Ltd', null, 'ACME Holdings'] (see Element indexes and staged values) is therefore searchable, and a subscript write (SET c.name[2] = '…') re-indexes the document.

Query with `SEARCH`

SEARCH :Article(body) FOR 'rooftop pool';            // → (node, score), best first
SEARCH :Article(body) FOR 'rooftop pool' LIMIT 10;   // cap the results

SEARCH returns nodes ranked by BM25 score, highest first (ties broken by ascending id). The query text is analysed with the same analyzer used at index time, so analysis is symmetric.

v1 semantics & limits

Bag-of-words with OR semantics: a document matches if it contains any query term; more/rarer matched terms score higher.
Not yet: phrase queries, stemming, fuzzy matching, boolean operators, positions/highlighting.

Remove the declaration after querying with DROP FULLTEXT INDEX ON :Article(body).

EXPLAIN and PROFILE · Resident and hybrid storage · Schema and maintenance procedures