Full-text Search is a PostgreSQL® feature that facilitates the indexing of natural language text documents, and in the identification of indexed documents that match a given query. Matching documents can be sorted based on their relevance to the query, and document excerpts can be generated with the matching terms highlighted. A set of SQL data types, operators, and functions are provided to assist with the indexing, querying, and ranking of documents.
PostgreSQL uses the term document to mean any fragment of natural language text— essentially, strings containing human-readable words separated by whitespace and punctuation. Documents are often stored as text columns but can also be generated dynamically—such as by concatenating multiple columns together (even from multiple tables).
Click through for the tutorial.