What data storage mechanism implements full-text search in the PostgreSQL database?

In PostgreSQL, full-text search is implemented using index mechanisms such as GiST (Generalized Search Tree) or GIN (Generalized Inverted Index). The core is the representation of text as tsvector — a structure that breaks down text into lexemes (words), normalizes them, and stores their positions.

For searching, tsquery is used — a query that is compared with tsvector. GIN indexes are especially efficient for quick searches across multiple words, as they build an inverted index that allows fast retrieval of documents containing the desired lexemes.

Example of creating an index for full-text search:

CREATE INDEX idx_fts ON documents USING GIN(to_tsvector('russian', content));

Then, queries can be performed:

SELECT * FROM documents WHERE to_tsvector('russian', content) @@ to_tsquery('russian', 'поиск & база');